Högskolan i Gävle Characterization of Stationary Concentrating Photovoltaic-Thermal Solar Collectors Prototypes [REESBE – Resource-Efficient Energy Systems in the Built Environment] João Gomes 2/2/2018 [Type the abstract of the document here


Högskolan i Gävle
Characterization of Stationary Concentrating Photovoltaic-Thermal Solar Collectors Prototypes
REESBE – Resource-Efficient Energy Systems in the Built Environment
João Gomes
2/2/2018
Type the abstract of the document here. The abstract is typically a short summary of the contents of the document. Type the abstract of the document here. The abstract is typically a short summary of the contents of the document.

Dedication
To Sara, my baby girl, so that she has the opportunity to discover this wonderful world, like I have had.

Acknowledgments

AbstractSammanfattning

Background and motivation for this workThis thesis is part of an Industrial PhD done within REESBE (Resource-Efficient Energy Systems in the Built Environment). This thesis was performed at the company Solarus Sunpower Sweden AB in Gävle, Sweden.

This work was aimed at detailing the scientific principles behind the Solarus concentrating photovoltaic-thermal (C-PVT) solar collector, which is a design with unique features. A better understanding of its own product will help the company to improve its product while, at the same, the knowledge generated will increase the scientific understanding on the issues around C-PVT panels and hopefully support future researchers in this topic.

Aims and Research QuestionsThe research questions include both broader solar aspects and very specific questions about C-PVT solar collectors:
1. How is the annual energy output ratio between PV and T collector varying around the world?
2. What are the most important parameters that define a concentrating PVT collector?
3. What type of reflector geometry is the most adequate for a stationary low concentration factor C-PVT?
4. What type of cell string layout is most adequate for a stationary low concentration factor C-PVT?
5. Is there good agreement between the results of the outdoor testing with the simulations in LTSPICE and raytracing Tonatiuh?
6. Which combination of materials and production processes allows silicone solar cells to resist the expansion of aluminum at stagnation temperatures of 200C?
LimitationsList of appended papers and author´s contribution7 papers were selected for the thesis.

Paper I: Gomes J., Junge J., Lehmann T. et Karlsson B. Defining An Annual Energy Output Ratio Between Solar Thermal Collectors And Photovoltaic Modules. Presented at IAHS Conference, 2016. Conference proceeding. Planned to be deepened and submitted to a journal in 2018.

Key Message: A new tool for comparison of T and PV technologies and market overview.
Author contribution: 90%. The author wrote the paper and did most of the work. The world maps, part of the market survey and some of the simulations were performed by Ms Junge and Ms Lehmann.

Paper II: Gomes J., Diwan L., Bernardo R. et Karlsson B. Minimizing the Impact of Shading at Oblique Solar Angles in a Fully Enclosed Asymmetric Concentrating PVT Collector. Presented at ISES Solar Conference 2013. Published in peer review Energy Procedia, Volume 57, 2014, p. 2176-2185 (Impact factor 1.16).  Available at https://doi.org/10.1016/j.egypro.2014.10.184Key Message: Analysis of the impact of shading in an asymmetric low concentration stationary PVT which including collector testing at two universities.

Author contribution: 85%. The author wrote the paper and did the majority of the work. Part of the collector testing work was conducted at Dalarna University by Mr Diwan with support from the author. The rest of the collector testing was done by the author at Gävle University.

Paper III: Gomes J., Bonfiglio ., Giovinazzo C., Fernandes C., Torres J., Olsson O., Branco P. et Nashih S. Analysis of C-PVT reflector geometries. Presented at the 17th international conference on power electronics and motion control. Available at DOI: 10.1109/EPEPEMC.2016.7752175. Submitted in April 2017 to a journal of IEEE: Transaction of Industrial Applications (Impact factor of 1.9). 
Key Message: Analysis of the raytracing results of different reflector geometries including costs/output balance. Author contribution: 85%. The author wrote the paper and did the majority of the work.

Paper IV: Giovinazzo C., Bonfiglio L., Gomes J. et Karlsson B. Ray Tracing Modelling of an Asymmetric Concentrating PVT. Presented at Eurosun 2014 and published in the conference proceedings (p.67). Available at DOI: 10.18086/eurosun.2014.21.01
Key Message: The Solarus C-PVT collector has been modelled using Tonaituh to extract a 3D map of the effective solar radiation that reaches both top and bottom sides of the receiver.

Author contribution: 65%. The author wrote the paper and supported Ms Giovinazzo and Mr Bonfiglio that performed the ray tracing simulations.

Paper V: Nashih S., Fernandes C. , Torres J., Gomes J. et Branco P. Validation of a Simulation Model for Analysis of Shading Effects on Photovoltaic Panels. Published on Journal of Solar Energy Engineering: Including Wind Energy and Building Energy Conservation, Volume 138, Issue, 14th June 2016 (Impact Factor 1.19). Available at DOI: 10.1115/1.4033646.

Key Message: Validation of the LTSpice model.

Author contribution: 50%. The author wrote part of the paper, did the experimental testing and supported both the theoretical and simulation work.

Paper VI: Fernandes C., Torres J., Branco P., Fernandes J. et Gomes J. Cell string layout in photovoltaic collectors. Published in Energy Conversion and Management journal, Volume 149, 1st October 2017, Pages 997-1009 (Impact Factor: 5.589). Available at DOI: 10.1016/j.enconman.2017.04.060.

Key Message: Simulations using an LTSPICE to predict the shading impact on a C-PVT. 
Author contribution: 40%. The author wrote part of the paper, did the experimental testing and supported both the theoretical and simulation work.

Paper VII: Bernardo R., Davidsson H., Gentile N., Gomes J., Gruffman C., Chea L., Mumba C. et Karlsson B. Measurements of the Electrical Incidence Angle Modifiers of an Asymmetrical Photovoltaic/Thermal Compound Parabolic Concentrating-Collector. Presented at PEEC 2013. Published in Engineering, Vol. 5 No. 1B, 2013, pp. 37-43 (Impact Factor: 0.72). Available at DOI: 10.4236/eng.2013.51B007.
Key Message: Characterization of the IAM of an early C-PVT prototype.

Author contribution: 40%. The team did the measurements and wrote part of the paper.

List of all papers from the author relevant to this thesisIn total, the author of this thesis has produced 22 papers in both conferences and journals. The list below shows all papers produced by the author of this thesis and categorizes them. Some of these papers were selected to be an integral part of this thesis as shown on the previous chapter while others were only used partially.
Paper VIII: Gomes J, Bastos S., Henriques M., Diwan L. et Olsson O. Evaluation of the Impact of Stagnation in Different Prototypes of Low Concentration PVT Solar Panels. Presented at the ISES world congress 2015 and published in the proceedings (p1025-1036). Available at DOI: 10.18086/swc.2015.10.14.

Key Message: Analysis on the impact of stagnation on solar cells encapsulated by silicone and different methods for mitigation of the impact.

Paper IX: Mantei F., Henriques M., Gomes J., Olsson O. et Karlsson B. The Night Cooling Effect on a C-PVT Solar Collector. Presented at the ISES world congress 2015 and published in the proceedings (p1199-1207). Available at DOI: 10.18086/swc.2015.10.33.

Key Message: Night cooling using glazed PVT´s collectors will work only under very few circumstances.

Paper X: Davidsson H., Bernardo R., Gomes J., Chea L., Gentile N. et Karlsson B. Construction of laboratories for solar energy research in developing countries. Presented at ISES Solar Conference 2013 and published at peer review Energy Proceedia, Volume 57, 2014, Pages 982-988 (Impact Factor: 1.16). DOI: 10.1016/j.egypro.2014.10.081.

Key Message: Study on the design and components for a solar lab for research and education in developing countries.

Paper XI: Gomes J., Gruffman C., Davidsson H., Maston S. et Karlsson B. Testing bifacial PV cells in symmetric and asymmetric concentrating CPC collectors. Presented at PEEC 2013. Published in Engineering, Vol. 5 No. 1B, 2013, PP. 185-190 (Impact Factor: 0.72). DOI: 10.4236/eng.2013.51B034.

Key Message: Different low concentration bi-facial PV collector prototypes were built and tested.

Paper XII: Gentile N., Davidsson H., Bernardo R., Gomes J., Gruffman C., Chea L., Mumba C. et Karlsson B. Construction of a small scale laboratory for solar collectors and solar cells in a developing country. Presented at PEEC 2013. Published in Engineering, Vol. 5 No. 1B, 2013, PP. PP. 75-80 (Impact Factor: 0.72). DOI: 10.4236/eng.2013.51B014.

Key Message: Developing and reducing the cost of components of solar collector testing labs while maintaining the necessary accuracy.

Paper XIII: Contero F., Gomes J., Mattias G. et Karlsson B. The impact of shading in the performance of three different solar PV systems. Presented at Eurosun 2016 and published in the proceedings. DOI: 10.18086/eurosun.2016.08.25.

Key Message: Evaluation of the electrical shading at HiG´s installation. Comparison between different shading mitigation devices.

Paper XIV: Gomes J. et Karlsson B. Analysis of the Incentives for Small Scale Photovoltaic Electricity Production in Portugal. Presented at Eurosun 2010 and published in the proceedings. DOI: 10.18086/eurosun.2010.08.05.

Key Message: Analysis of the impact of the incentive schemes in PV penetration.

Paper XV: Gomes J. et Karlsson B. Analysis of Reflector Geometries for Flat Collectors. Presented at Renewable Energy Conference, Yokohama, Japan, 2010.

Key Message: Analysis on the best point for truncation for reflectors in concentrating solar thermal collectors.

Paper XVI: Diogo Cabral, Paul-Antoine Dostie-Guindon, João Gomes et Björn Karlsson. Ray Tracing Simulations of a Novel Low Concentrator PVT Solar Collector for Low Latitudes. Presented at ISES solar world congress 2017 and will be published in the conference proceedings.
Key Message: Comparison between different reflector geometries for a low concentrating PVT using Tonatiuh ray tracing.

Paper XVII: Alves P., Fernandes J., Torres J., Branco P., Fernandes C., Gomes J. Energy Efficiency of a PV/T Collector for Domestic Water Heating Installed in Sweden or in Portugal: The Impact of Heat Pipe Cross-Section Geometry and Water Flowing Speed. Presented at the 12th SDEWES conference in 2017 and published in the proceedings.

Key Message: Simulations were conducted to verify the influence of the flow, losses in electric efficiency, temperature variation, shading effect in the back receiver of electrical efficiency in Portugal and Sweden.

Paper XVIII: Fernandes C., Torres J., Nashih S., Gomes J. et Branco P. Effect of reflector geometry in the annual received radiation of low concentration PV systems. Submitted on Dez 2017 to IEEE Transactions on Industry Applications (TIA)
Key Message: Soltrace simulations.

Paper XIX: Fernandes C., Torres J., Nashih S., Gomes J. et Branco P. Cell string layout in a stationary solar concentrating solar photovoltaic collectors. Published in Power Electronics and Motion Control Conference (PEMC), 2016 IEEE. DOI: 10.1109/EPEPEMC.2016.7752179Key Message: Simulations using an LTSPICE to predict the shading influence in a C-PVT.

Paper XX: Torres J., Nashih S., Fernandes C. et Gomes J. The effect of shading on photovoltaic solar panels. Published October 2016 in Energy Systems, page 1-14 (Impact Factor 0.912). DOI: 10.1007/s12667-016-0225-5
Key Message: LTSPICE study on the shading impact in a PVT.

Paper XXI: Fernandes C., Torres J., Nashih S., Gomes J. et Branco P. Shading Effects on Photovoltaic Panels. Presented at Conftele conference at Aveiro University 2015. Conference proceeding.

Key Message: Early shading study with LTSPICE.

Paper XXII: Kurdia A., Gomes J., Olsson O., Ollas P. et Karlsson B. Quasi-dynamic testing of a novel concentrating solar collector according to ISO 9806:2013. Submitted to Eurosun 2018.
Key Message: Comparison of the testing results between the Solarus C-PVT and a standard flat plate
Paper XXIII: Torres J., Fernandes C., Gomes J., Olsson O., Bonfiglio L., Giovinazzo C. et Branco P. Effect of Reflector Geometry in the Annual Received Radiation of Low Concentration Photovoltaic Systems. Published in Energy 2018, 11(7), 1878 (Impact Factor 3.05); DOI: 10.3390/en11071878
Key Message: Analysis of different reflector geometries using the soltrace software.

Note: References to the above papers will be marked as, for example, XXIII.
Literature reviewClimate change”Today, like always before, society faces its gravest challenge.”
Although, current challenges always appear to be the most pressing as the above quote somewhat cynically postulates, it is nevertheless an objective and undeniable reality that mankind today has an unprecedented capacity to alter the planet which supports its life.

And, in its quest to improve its life quality, mankind as created environmental problems that today threaten its very survival. Climate change is a reality and must be tackled, if humans are to continue to exist.

Figure 1 shows the temperature data from four reputable international science institutions. All show rapid warming in the past few decades and that the last decade has been the warmest on record ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”r1xTKL6t”,”properties”:{“formattedCitation”:”1″,”plainCitation”:”1″,”noteIndex”:0},”citationItems”:{“id”:7,”uris”:”http://zotero.org/users/4612010/items/AR53B544″,”uri”:”http://zotero.org/users/4612010/items/AR53B544″,”itemData”:{“id”:7,”type”:”webpage”,”title”:”NASA (Global Surface Temperatures)”,”URL”:”https://www.nasa.gov/pdf/509983main_adjusted_annual_temperature_anomalies%20_final.pdf”,”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 1.
3247390556895Sources: NASA’s Goddard Institute for Space Studies, NOAA National Climatic Data Center, Met Office Hadley Centre/Climatic Research Unit and the Japanese Meteorological Agency.

00Sources: NASA’s Goddard Institute for Space Studies, NOAA National Climatic Data Center, Met Office Hadley Centre/Climatic Research Unit and the Japanese Meteorological Agency.

3313771432869Figure 1: Planetary temperatures over the last 140 years0Figure 1: Planetary temperatures over the last 140 yearsFigure 2 clearly shows not only how large the atmospheric CO2 increase since the Industrial Revolution has been, but also how drastically fast the planetary balance of the last 400000 years has been disrupted. This figure was made based on the comparison of atmospheric samples contained in ice cores and more recent direct measurements ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a1jlhvdvjn”,”properties”:{“formattedCitation”:”2″,”plainCitation”:”2″,”noteIndex”:0},”citationItems”:{“id”:4,”uris”:”http://zotero.org/users/4612010/items/FDK3447D”,”uri”:”http://zotero.org/users/4612010/items/FDK3447D”,”itemData”:{“id”:4,”type”:”article-journal”,”title”:”Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica”,”container-title”:”Nature”,”page”:”429″,”volume”:”399″,”issue”:”6735″,”source”:”www.nature.com”,”abstract”:”Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica”,”DOI”:”10.1038/20859″,”ISSN”:”1476-4687″,”language”:”En”,”author”:{“family”:”Petit”,”given”:”J. R.”},{“family”:”Jouzel”,”given”:”J.”},{“family”:”Raynaud”,”given”:”D.”},{“family”:”Barkov”,”given”:”N. I.”},{“family”:”Barnola”,”given”:”J.-M.”},{“family”:”Basile”,”given”:”I.”},{“family”:”Bender”,”given”:”M.”},{“family”:”Chappellaz”,”given”:”J.”},{“family”:”Davis”,”given”:”M.”},{“family”:”Delaygue”,”given”:”G.”},{“family”:”Delmotte”,”given”:”M.”},{“family”:”Kotlyakov”,”given”:”V. M.”},{“family”:”Legrand”,”given”:”M.”},{“family”:”Lipenkov”,”given”:”V. Y.”},{“family”:”Lorius”,”given”:”C.”},{“family”:”PÉpin”,”given”:”L.”},{“family”:”Ritz”,”given”:”C.”},{“family”:”Saltzman”,”given”:”E.”},{“family”:”Stievenard”,”given”:”M.”},”issued”:{“date-parts”:”1999″,6}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 2.
Figure SEQ Figure * ARABIC 2: Variation of atmospheric carbon dioxide levels over 400.000 years(Source: Vostok ice core data/J.R. Petit et al.; NOAA Mauna Loa CO2 record)
Lüthi et all, plotted CO2 levels during 800000 years and the cycles still remain between 160 and 300 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a26tvo03478″,”properties”:{“formattedCitation”:”3″,”plainCitation”:”3″,”noteIndex”:0},”citationItems”:{“id”:8,”uris”:”http://zotero.org/users/4612010/items/5HYI2TN3″,”uri”:”http://zotero.org/users/4612010/items/5HYI2TN3″,”itemData”:{“id”:8,”type”:”article-journal”,”title”:”High-resolution carbon dioxide concentration record 650,000–800,000 years before present”,”container-title”:”Nature”,”page”:”379-382″,”volume”:”453″,”issue”:”7193″,”source”:”CrossRef”,”DOI”:”10.1038/nature06949″,”ISSN”:”0028-0836, 1476-4687″,”author”:{“family”:”Lüthi”,”given”:”Dieter”},{“family”:”Le Floch”,”given”:”Martine”},{“family”:”Bereiter”,”given”:”Bernhard”},{“family”:”Blunier”,”given”:”Thomas”},{“family”:”Barnola”,”given”:”Jean-Marc”},{“family”:”Siegenthaler”,”given”:”Urs”},{“family”:”Raynaud”,”given”:”Dominique”},{“family”:”Jouzel”,”given”:”Jean”},{“family”:”Fischer”,”given”:”Hubertus”},{“family”:”Kawamura”,”given”:”Kenji”},{“family”:”Stocker”,”given”:”Thomas F.”},”issued”:{“date-parts”:”2008″,5,15}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 3. As a time reference for comparison, Homo sapiens, the first modern humans have evolved from their early hominid predecessors about 250000 years ago, language was developed about 50000 years ago and the great migration from Africa started about 70000 years ago ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”ajqof62sfr”,”properties”:{“formattedCitation”:”4″,”plainCitation”:”4″,”noteIndex”:0},”citationItems”:{“id”:9,”uris”:”http://zotero.org/users/4612010/items/2DPHWSUU”,”uri”:”http://zotero.org/users/4612010/items/2DPHWSUU”,”itemData”:{“id”:9,”type”:”article-journal”,”title”:”Human origins: Out of Africa”,”container-title”:”Proceedings of the National Academy of Sciences”,”page”:”16018-16021″,”volume”:”106″,”issue”:”38″,”source”:”www.pnas.org”,”abstract”:”Our species, Homo sapiens, is highly autapomorphic (uniquely derived) among hominids in the structure of its skull and postcranial skeleton. It is also sharply distinguished from other organisms by its unique symbolic mode of cognition. The fossil and archaeological records combine to show fairly clearly that our physical and cognitive attributes both first appeared in Africa, but at different times. Essentially modern bony conformation was established in that continent by the 200–150 Ka range (a dating in good agreement with dates for the origin of H. sapiens derived from modern molecular diversity). The event concerned was apparently short-term because it is essentially unanticipated in the fossil record. In contrast, the first convincing stirrings of symbolic behavior are not currently detectable until (possibly well) after 100 Ka. The radical reorganization of gene expression that underwrote the distinctive physical appearance of H. sapiens was probably also responsible for the neural substrate that permits symbolic cognition. This exaptively acquired potential lay unexploited until it was “discovered” via a cultural stimulus, plausibly the invention of language. Modern humans appear to have definitively exited Africa to populate the rest of the globe only after both their physical and cognitive peculiarities had been acquired within that continent.”,”DOI”:”10.1073/pnas.0903207106″,”ISSN”:”0027-8424, 1091-6490″,”note”:”PMID: 19805256″,”shortTitle”:”Human origins”,”journalAbbreviation”:”PNAS”,”language”:”en”,”author”:{“family”:”Tattersall”,”given”:”Ian”},”issued”:{“date-parts”:”2009″,9,22}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 4. Mankind has existed always within this range of atmospheric CO2. Climate change impacts are multiple from acidification of the oceans to melting of the polar caps. Furthermore, the greenhouse effect may make planetary and regional temperatures spiral out of control. And while, there is no crystal ball to accurately predict the future, we know that the climate balance that allowed humans to thrive will be greatly disturbed. At a planetary level, this would be just one of many climate changes, and it is even likely that a percentage of the current species would adapt to survive a major climate change. However, it is likely that humans are too dependent on the global ecosystem to survive such changes. And this is definitely a risk that is not worth taking.
Overview of the Energy SectorEnergy use is one of the most important cause of climate change. As a result, mankind needs to convert to low CO2 emitting energy sources, preferably renewable which are sustainable in the long run.

Energy is used in two forms: Heat and electricity. The graph below illustrates the shares of the different energy sources in the world´s final energy consumption.

Figure SEQ Figure * ARABIC 3: Estimated Renewable Energy Share of Global Final Energy Consumption in 2014 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”aekedp6mdl”,”properties”:{“formattedCitation”:”5″,”plainCitation”:”5″,”noteIndex”:0},”citationItems”:{“id”:15,”uris”:”http://zotero.org/users/4612010/items/54WRGLFE”,”uri”:”http://zotero.org/users/4612010/items/54WRGLFE”,”itemData”:{“id”:15,”type”:”book”,”title”:”Renewables 2016 Global Status Report”,”source”:”Open WorldCat”,”URL”:”https://apps.uqo.ca/LoginSigparb/LoginPourRessources.aspx?url=http://www.deslibris.ca/ID/10091391″,”ISBN”:”978-3-9818107-0-7″,”note”:”OCLC: 1010981965″,”language”:”English”,”author”:{“family”:”Zervos”,”given”:”Arthouros”},{“family”:”Lins”,”given”:”Christine”},”issued”:{“date-parts”:”2016″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 5
According to the REN21, renewable energy reports, in 2009, the share of renewable energy in the total energy usage of the world was 16% 6. In 2014, the same share was 19.2%, up 3,2% in 5 years ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a12a8tj2jlu”,”properties”:{“formattedCitation”:”5″,”plainCitation”:”5″,”noteIndex”:0},”citationItems”:{“id”:15,”uris”:”http://zotero.org/users/4612010/items/54WRGLFE”,”uri”:”http://zotero.org/users/4612010/items/54WRGLFE”,”itemData”:{“id”:15,”type”:”book”,”title”:”Renewables 2016 Global Status Report”,”source”:”Open WorldCat”,”URL”:”https://apps.uqo.ca/LoginSigparb/LoginPourRessources.aspx?url=http://www.deslibris.ca/ID/10091391″,”ISBN”:”978-3-9818107-0-7″,”note”:”OCLC: 1010981965″,”language”:”English”,”author”:{“family”:”Zervos”,”given”:”Arthouros”},{“family”:”Lins”,”given”:”Christine”},”issued”:{“date-parts”:”2016″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 5.

In the same period, modern renewables accounted for the bulk of the increase, from 6% to 10.3% of the world´s energy usage. Traditional biomass relevance has decreased by 1.1%, from 10% to 8.9% ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”amb0a0cusa”,”properties”:{“formattedCitation”:”6″,”plainCitation”:”6″,”noteIndex”:0},”citationItems”:{“id”:16,”uris”:”http://zotero.org/users/4612010/items/UYM7DBPT”,”uri”:”http://zotero.org/users/4612010/items/UYM7DBPT”,”itemData”:{“id”:16,”type”:”article-journal”,”title”:”Renewable Energy Policy Network for the 21st Century”,”source”:”Google Scholar”,”author”:{“family”:”Junfeng”,”given”:”Li”},{“family”:”Lohani”,”given”:”Bindu”},{“family”:”Galàn”,”given”:”Ernesto Macìas”},{“family”:”Monga”,”given”:”Pradeep”},{“family”:”Mubiru”,”given”:”Paul”},{“family”:”Nakicenovic”,”given”:”Nebojsa”},{“family”:”Nassiep”,”given”:”Kevin”},{“family”:”Pachauri”,”given”:”Rajendra”},{“family”:”Palz”,”given”:”Wolfgang”},{“family”:”Pelosse”,”given”:”Hélène”}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 6.

Regarding renewable electricity, the year of 2015 saw the largest increase ever of 147 GW of total capacity added. This represented an increase of almost 9% to a total installed capacity of 1849 GW ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a2nvhd6l1nt”,”properties”:{“formattedCitation”:”5″,”plainCitation”:”5″,”noteIndex”:0},”citationItems”:{“id”:15,”uris”:”http://zotero.org/users/4612010/items/54WRGLFE”,”uri”:”http://zotero.org/users/4612010/items/54WRGLFE”,”itemData”:{“id”:15,”type”:”book”,”title”:”Renewables 2016 Global Status Report”,”source”:”Open WorldCat”,”URL”:”https://apps.uqo.ca/LoginSigparb/LoginPourRessources.aspx?url=http://www.deslibris.ca/ID/10091391″,”ISBN”:”978-3-9818107-0-7″,”note”:”OCLC: 1010981965″,”language”:”English”,”author”:{“family”:”Zervos”,”given”:”Arthouros”},{“family”:”Lins”,”given”:”Christine”},”issued”:{“date-parts”:”2016″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 5.

Both Wind and Solar PV made record additions and together they made up 77% of all renewable power capacity added in 2015 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”av2pgkbadm”,”properties”:{“formattedCitation”:”5″,”plainCitation”:”5″,”noteIndex”:0},”citationItems”:{“id”:15,”uris”:”http://zotero.org/users/4612010/items/54WRGLFE”,”uri”:”http://zotero.org/users/4612010/items/54WRGLFE”,”itemData”:{“id”:15,”type”:”book”,”title”:”Renewables 2016 Global Status Report”,”source”:”Open WorldCat”,”URL”:”https://apps.uqo.ca/LoginSigparb/LoginPourRessources.aspx?url=http://www.deslibris.ca/ID/10091391″,”ISBN”:”978-3-9818107-0-7″,”note”:”OCLC: 1010981965″,”language”:”English”,”author”:{“family”:”Zervos”,”given”:”Arthouros”},{“family”:”Lins”,”given”:”Christine”},”issued”:{“date-parts”:”2016″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 5.

A landmark change is the fact that today the world adds more renewable power capacity annually than what it adds in net capacity from all fossil fuels combined! This way, in 2015, renewables have accounted for 60% of all net additions to global power generating capacity ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a2fiomdoe1s”,”properties”:{“formattedCitation”:”5″,”plainCitation”:”5″,”noteIndex”:0},”citationItems”:{“id”:15,”uris”:”http://zotero.org/users/4612010/items/54WRGLFE”,”uri”:”http://zotero.org/users/4612010/items/54WRGLFE”,”itemData”:{“id”:15,”type”:”book”,”title”:”Renewables 2016 Global Status Report”,”source”:”Open WorldCat”,”URL”:”https://apps.uqo.ca/LoginSigparb/LoginPourRessources.aspx?url=http://www.deslibris.ca/ID/10091391″,”ISBN”:”978-3-9818107-0-7″,”note”:”OCLC: 1010981965″,”language”:”English”,”author”:{“family”:”Zervos”,”given”:”Arthouros”},{“family”:”Lins”,”given”:”Christine”},”issued”:{“date-parts”:”2016″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 5.

By the end of 2015, renewables represent 29% of the world’s power generating capacity, which supplied 23.7% of global electricity, with hydropower representing 16.6%.
Figure SEQ Figure * ARABIC 4: Estimated share of Renewable Energy in Global Electricity Production in 2015 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a2ne7mujbfp”,”properties”:{“formattedCitation”:”5″,”plainCitation”:”5″,”noteIndex”:0},”citationItems”:{“id”:15,”uris”:”http://zotero.org/users/4612010/items/54WRGLFE”,”uri”:”http://zotero.org/users/4612010/items/54WRGLFE”,”itemData”:{“id”:15,”type”:”book”,”title”:”Renewables 2016 Global Status Report”,”source”:”Open WorldCat”,”URL”:”https://apps.uqo.ca/LoginSigparb/LoginPourRessources.aspx?url=http://www.deslibris.ca/ID/10091391″,”ISBN”:”978-3-9818107-0-7″,”note”:”OCLC: 1010981965″,”language”:”English”,”author”:{“family”:”Zervos”,”given”:”Arthouros”},{“family”:”Lins”,”given”:”Christine”},”issued”:{“date-parts”:”2016″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 5
By 2040, it is expected that the cumulative growth of RE will contribute to a total primary energy consumption to 50% ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a126totg9oi”,”properties”:{“formattedCitation”:”7″,”plainCitation”:”7″,”noteIndex”:0},”citationItems”:{“id”:17,”uris”:”http://zotero.org/users/4612010/items/2I9RHWJU”,”uri”:”http://zotero.org/users/4612010/items/2I9RHWJU”,”itemData”:{“id”:17,”type”:”article-journal”,”title”:”Renewable energy integrated desalination: A sustainable solution to overcome future fresh-water scarcity in India”,”container-title”:”Renewable and Sustainable Energy Reviews”,”page”:”594-609″,”volume”:”73″,”issue”:”C”,”source”:”RePEc – Econpapers”,”abstract”:”Fossil fuels such as coal, petroleum, and natural gas have been used as the major sources of energy in the recent past. However, the negative environmental impacts associated with the emission of the greenhouse gases from these conventional energy sources forced to realize the importance of renewable energy resources. At the same time, the average annual exponential rate of population growth in India needs increasing amounts of fresh-water for the basic necessities. This might result in water scarcity as the overall population in India is expected to increase to 1.60 billion by 2050. It has been forecasted that, by the year 2040, India will rank 40th in the world in terms of water scarcity. To meet the rising fresh-water demand, desalination is an intelligent and sustainable option for India, which has a very long coastline measuring 7517km. In this paper, an attempt has been made to provide a comprehensive review of water scarcity in India and suggest a possible solution, which is implementing desalination technologies coupled with renewable resources. The paper reviews the ground water scenario in India and the global desalination market. We summarize the energy consumption in various desalination processes and provide a brief outlook of the desalination techniques in India. Apart from this, desalination using non-conventional sources such as solar, wind, and geothermal energy is discussed. In addition, factors affecting the environment due to desalination and the potential counter measures are presented. 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Solar Energy: PV and Thermal collectorsEnergy from solar radiation can be collected in two forms:
Solar Electricity
Solar Heat
1) Solar Electricity
Solar Electricity is either produced by the photovoltaic (PV) effect or by the conversion of solar radiation into heat which is then used to drive a turbine that generates electricity. The latest process can only be achieved in large centralized power plants and is called Concentrated Solar Power (CSP).

In 2015, CSP had a total installed capacity of 5 GW which compares to 227 GW of PV. In the same year, 50 GW of PV have been installed ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a2bhkeufm7d”,”properties”:{“formattedCitation”:”5″,”plainCitation”:”5″,”noteIndex”:0},”citationItems”:{“id”:15,”uris”:”http://zotero.org/users/4612010/items/54WRGLFE”,”uri”:”http://zotero.org/users/4612010/items/54WRGLFE”,”itemData”:{“id”:15,”type”:”book”,”title”:”Renewables 2016 Global Status Report”,”source”:”Open WorldCat”,”URL”:”https://apps.uqo.ca/LoginSigparb/LoginPourRessources.aspx?url=http://www.deslibris.ca/ID/10091391″,”ISBN”:”978-3-9818107-0-7″,”note”:”OCLC: 1010981965″,”language”:”English”,”author”:{“family”:”Zervos”,”given”:”Arthouros”},{“family”:”Lins”,”given”:”Christine”},”issued”:{“date-parts”:”2016″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 5. Although only 10 years ago, CSP was expected to become the mainstream of solar electricity production method, PV has managed to greatly surpass CSP having today a total installed capacity that is 45 times higher. This is probably due to the simplicity and modularity of PV installations which overall has much lower capital requirements than CSP. However, thermal storage can help CSP to gain momentum, as it allows CSP to do baseload. In 2016, all CSP plants where built with storage ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a1926jneeo5″,”properties”:{“formattedCitation”:”9″,”plainCitation”:”9″,”noteIndex”:0},”citationItems”:{“id”:112,”uris”:”http://zotero.org/users/4612010/items/KJ2BPPU9″,”uri”:”http://zotero.org/users/4612010/items/KJ2BPPU9″,”itemData”:{“id”:112,”type”:”book”,”title”:”Renewables 2017 Global Status Report”,”source”:”Open WorldCat”,”URL”:”https://apps.uqo.ca/LoginSigparb/LoginPourRessources.aspx?url=http://www.deslibris.ca/ID/10091391″,”ISBN”:”978-3-9818107-0-7″,”note”:”OCLC: 1010981965″,”language”:”English”,”author”:{“family”:”Zervos”,”given”:”Arthouros”},{“family”:”Lins”,”given”:”Christine”},”issued”:{“date-parts”:”2017″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 9.

The growth in PV has been so fast that capacity installed in the world in 2015 is nearly 10 times higher than the cumulative installed capacity of 2005 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a9vo9j7tus”,”properties”:{“formattedCitation”:”8″,”plainCitation”:”8″,”noteIndex”:0},”citationItems”:{“id”:24,”uris”:”http://zotero.org/users/4612010/items/3ECNVTNS”,”uri”:”http://zotero.org/users/4612010/items/3ECNVTNS”,”itemData”:{“id”:24,”type”:”article-journal”,”title”:”A comprehensive review on large-scale photovoltaic system with applications of electrical energy storage”,”container-title”:”Renewable and Sustainable Energy Reviews”,”page”:”439-451″,”volume”:”78″,”issue”:”C”,”source”:”ideas.repec.org”,”abstract”:”In order to mitigate energy crisis and to meet carbon-emission reduction targets, the use of electrical energy produced by solar photovoltaic (PV) is inevitable. To meet the global increasing energy demand, PV power capacity will be expanded ranging from large-scale (from ten to several hundred MWs) PV farms at high and medium voltage level to kilowatt residential PV systems at low voltage level. It is expected that the PV penetration will increase in power systems with the retirement of traditional carbon-emission emitting power plants. Solar energy is diurnal in nature and in practice, it is highly uncertain due to various perturbation effects. With the recent technological advancements and rapid cost reductions in electrical energy storage (EES), EES could be deployed to enhance the system’s performance and stability. This paper presents a comprehensive review on the emerging high penetration of PV with an overview of EES for PV systems. The crucial element, the building block of solar panel and the solar cell are reviewed. The emerging cell technologies are presented. A study of solar power forecasting techniques, an important tool for the successful operation and planning of PV and EES is included. A selection of EES is presented and studied for PV system purposes. Future research and areas for improvements in recent works and related areas are identified.”,”language”:”en”,”author”:{“family”:”Lai”,”given”:”Chun Sing”},{“family”:”Jia”,”given”:”Youwei”},{“family”:”Lai”,”given”:”Loi Lei”},{“family”:”Xu”,”given”:”Zhao”},{“family”:”McCulloch”,”given”:”Malcolm D.”},{“family”:”Wong”,”given”:”Kit Po”},”issued”:{“date-parts”:”2017″}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 8.

The figure below shows the top 10 countries in total installed capacity of PV. Germany has been the installed capacity leader for the last decade however, in 2015, China took the lead ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a1aloi2aits”,”properties”:{“formattedCitation”:”5″,”plainCitation”:”5″,”noteIndex”:0},”citationItems”:{“id”:15,”uris”:”http://zotero.org/users/4612010/items/54WRGLFE”,”uri”:”http://zotero.org/users/4612010/items/54WRGLFE”,”itemData”:{“id”:15,”type”:”book”,”title”:”Renewables 2016 Global Status Report”,”source”:”Open WorldCat”,”URL”:”https://apps.uqo.ca/LoginSigparb/LoginPourRessources.aspx?url=http://www.deslibris.ca/ID/10091391″,”ISBN”:”978-3-9818107-0-7″,”note”:”OCLC: 1010981965″,”language”:”English”,”author”:{“family”:”Zervos”,”given”:”Arthouros”},{“family”:”Lins”,”given”:”Christine”},”issued”:{“date-parts”:”2016″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 5. In 2016, Japan became second ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a14k6bq658″,”properties”:{“formattedCitation”:”9″,”plainCitation”:”9″,”noteIndex”:0},”citationItems”:{“id”:112,”uris”:”http://zotero.org/users/4612010/items/KJ2BPPU9″,”uri”:”http://zotero.org/users/4612010/items/KJ2BPPU9″,”itemData”:{“id”:112,”type”:”book”,”title”:”Renewables 2017 Global Status Report”,”source”:”Open WorldCat”,”URL”:”https://apps.uqo.ca/LoginSigparb/LoginPourRessources.aspx?url=http://www.deslibris.ca/ID/10091391″,”ISBN”:”978-3-9818107-0-7″,”note”:”OCLC: 1010981965″,”language”:”English”,”author”:{“family”:”Zervos”,”given”:”Arthouros”},{“family”:”Lins”,”given”:”Christine”},”issued”:{“date-parts”:”2017″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 9. A major shift has also happened in PV production in the world. According to the REN21 2014 report: “Less than 10 years ago, almost all solar panels were produce Europe, Japan and the USA. In 2013, Asia accounted for 87% of global production (up from 85% in 2012) with China producing 67% of the world total (62% in 2012). Europe´s share continue to fall to 9% while Japan remained at 5% and the US at only 2.6%”. ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a1kvtcups66″,”properties”:{“formattedCitation”:”10″,”plainCitation”:”10″,”noteIndex”:0},”citationItems”:{“id”:110,”uris”:”http://zotero.org/users/4612010/items/G73YJTVP”,”uri”:”http://zotero.org/users/4612010/items/G73YJTVP”,”itemData”:{“id”:110,”type”:”book”,”title”:”Renewables 2014 Global Status Report”,”source”:”Open WorldCat”,”URL”:”http://large.stanford.edu/courses/2014/ph240/singh1/docs/GSR2014.pdf”,”note”:”OCLC: 1010981965″,”language”:”English”,”author”:{“family”:”Zervos”,”given”:”Arthouros”},{“family”:”Lins”,”given”:”Christine”},”issued”:{“date-parts”:”2014″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 10left211536600
Figure SEQ Figure * ARABIC 5: Installed capacity and new additions of PV in 2016 for the top 10 countries ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a1ur6p18t35″,”properties”:{“formattedCitation”:”9″,”plainCitation”:”9″,”noteIndex”:0},”citationItems”:{“id”:112,”uris”:”http://zotero.org/users/4612010/items/KJ2BPPU9″,”uri”:”http://zotero.org/users/4612010/items/KJ2BPPU9″,”itemData”:{“id”:112,”type”:”book”,”title”:”Renewables 2017 Global Status Report”,”source”:”Open WorldCat”,”URL”:”https://apps.uqo.ca/LoginSigparb/LoginPourRessources.aspx?url=http://www.deslibris.ca/ID/10091391″,”ISBN”:”978-3-9818107-0-7″,”note”:”OCLC: 1010981965″,”language”:”English”,”author”:{“family”:”Zervos”,”given”:”Arthouros”},{“family”:”Lins”,”given”:”Christine”},”issued”:{“date-parts”:”2017″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 9
Moreover, it is important to note that several PV technologies exist with very different efficiencies and development stages. However, silicone solar cells are today the dominating PV technology with about 90% of the PV market. Within this, monocrystalline silicone cells represent about 25% of the world panel production in 2015 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a1534an296s”,”properties”:{“formattedCitation”:”11″,”plainCitation”:”11″,”noteIndex”:0},”citationItems”:{“id”:28,”uris”:”http://zotero.org/users/4612010/items/4XPKIGKT”,”uri”:”http://zotero.org/users/4612010/items/4XPKIGKT”,”itemData”:{“id”:28,”type”:”webpage”,”title”:”Crystalline Silicon Photovoltaics Research | Department of Energy”,”URL”:”https://www.energy.gov/eere/solar/crystalline-silicon-photovoltaics-research”,”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 11 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a2ct7fo9t2s”,”properties”:{“formattedCitation”:”12″,”plainCitation”:”12″,”noteIndex”:0},”citationItems”:{“id”:129,”uris”:”http://zotero.org/users/4612010/items/299VNVDP”,”uri”:”http://zotero.org/users/4612010/items/299VNVDP”,”itemData”:{“id”:129,”type”:”article-journal”,”title”:”Latest Trends in Development and Manufacturing of Industrial, Crystalline Silicon Solar-Cells”,”container-title”:”Energy Procedia”,”collection-title”:”Proceedings of the SiliconPV 2011 Conference (1st International Conference on Crystalline Silicon Photovoltaics)”,”page”:”2-8″,”volume”:”8″,”source”:”ScienceDirect”,”abstract”:”Reliability, performance and cost are the key parameters for all PV products. The technology dominating the PV market until today with a market share of ?80% is the very robust and versatile double-side contacted silicon solar-cell. During previous years the development and manufacturing of this standard cell architecture has been very successful with respect to the continuous reduction of unit-cost and improvement in efficiency, maintaining its dominance in the PV arena despite a huge number of competing thick- and thin-film concepts and technologies. In this paper we present an overview about the ongoing development and manufacturing activities at Q-Cells, which show, that also for the next years to come, the continuous improvement of the standard cell architecture still has an enormous potential with respect to cost and efficiency and hence to €/Wp and finally €/kWh reduction. The main levers are the optimization of optical and electrical front side properties and the successful transfer of low cost backside passivation and metallization concepts from the R&D lab into pilot- and finally high volume production. We applied these well known concepts to our 6″ p-type standard monoand multi-crystalline wafers including umg-Si. The results, achieved in our R;D Pilot Production facility at Thalheim, show stable median efficiencies exceeding 19% for our mono- and 18% for our multi-crystalline solar cells including umg-Si. These cells feature a lowly doped emitter, a fineline-printed Ag grid and a dielectric passivated rear with point contacts. Narrow efficiency distributions are achieved with help of laser marked single wafer tracking, enabling sophisticated equipment and process control. 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It is also important to note that “Solar PV saw record additions and, for the first time, accounted for more additional power capacity (net of decommissioned capacity) than any other renewable technology. Solar PV represented about 47% of newly installed renewable power capacity in 2016, while wind and hydropower accounted for most of the remainder, contributing about 34% and 15.5%, respectively”. ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”gjehrj61″,”properties”:{“formattedCitation”:”9″,”plainCitation”:”9″,”noteIndex”:0},”citationItems”:{“id”:112,”uris”:”http://zotero.org/users/4612010/items/KJ2BPPU9″,”uri”:”http://zotero.org/users/4612010/items/KJ2BPPU9″,”itemData”:{“id”:112,”type”:”book”,”title”:”Renewables 2017 Global Status Report”,”source”:”Open WorldCat”,”URL”:”https://apps.uqo.ca/LoginSigparb/LoginPourRessources.aspx?url=http://www.deslibris.ca/ID/10091391″,”ISBN”:”978-3-9818107-0-7″,”note”:”OCLC: 1010981965″,”language”:”English”,”author”:{“family”:”Zervos”,”given”:”Arthouros”},{“family”:”Lins”,”given”:”Christine”},”issued”:{“date-parts”:”2017″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 9
2) Solar Heat
Solar Heat or Solar Thermal (ST) is the process of converting solar radiation into heat. A large number of different technologies exists ranging from uncovered flat plate collectors, to vacuum tube collectors or large tracking concentrating solar collectors. These technologies produce heat at different temperatures and therefore have multiple applications in residential and industrial sectors.

The figure below shows the total installed capacity in 2016 of solar heating in the world at 456 GWth. As a referential, one can compare to the 303 GWe of installed capacity PV ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a7uusoc4o5″,”properties”:{“formattedCitation”:”9″,”plainCitation”:”9″,”noteIndex”:0},”citationItems”:{“id”:112,”uris”:”http://zotero.org/users/4612010/items/KJ2BPPU9″,”uri”:”http://zotero.org/users/4612010/items/KJ2BPPU9″,”itemData”:{“id”:112,”type”:”book”,”title”:”Renewables 2017 Global Status Report”,”source”:”Open WorldCat”,”URL”:”https://apps.uqo.ca/LoginSigparb/LoginPourRessources.aspx?url=http://www.deslibris.ca/ID/10091391″,”ISBN”:”978-3-9818107-0-7″,”note”:”OCLC: 1010981965″,”language”:”English”,”author”:{“family”:”Zervos”,”given”:”Arthouros”},{“family”:”Lins”,”given”:”Christine”},”issued”:{“date-parts”:”2017″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 9, although it is fundamental to keep in mind that PV and ST have different capacity factors and that they produce energy with different values. The 456 GWth of ST are estimated to have produced 375 TWh of heat at different temperatures. At the same time, the 303 GW of PV produced about 375 TWh ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”e071lAHx”,”properties”:{“formattedCitation”:”9″,”plainCitation”:”9″,”noteIndex”:0},”citationItems”:{“id”:112,”uris”:”http://zotero.org/users/4612010/items/KJ2BPPU9″,”uri”:”http://zotero.org/users/4612010/items/KJ2BPPU9″,”itemData”:{“id”:112,”type”:”book”,”title”:”Renewables 2017 Global Status Report”,”source”:”Open WorldCat”,”URL”:”https://apps.uqo.ca/LoginSigparb/LoginPourRessources.aspx?url=http://www.deslibris.ca/ID/10091391″,”ISBN”:”978-3-9818107-0-7″,”note”:”OCLC: 1010981965″,”language”:”English”,”author”:{“family”:”Zervos”,”given”:”Arthouros”},{“family”:”Lins”,”given”:”Christine”},”issued”:{“date-parts”:”2017″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 9.

In 2017, China alone has accounted for 75% of the total new additions. The Chinese market has been undergoing a change from small residential to large installations such has hotels or the public sector ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a18dndb6jo0″,”properties”:{“formattedCitation”:”9″,”plainCitation”:”9″,”noteIndex”:0},”citationItems”:{“id”:112,”uris”:”http://zotero.org/users/4612010/items/KJ2BPPU9″,”uri”:”http://zotero.org/users/4612010/items/KJ2BPPU9″,”itemData”:{“id”:112,”type”:”book”,”title”:”Renewables 2017 Global Status Report”,”source”:”Open WorldCat”,”URL”:”https://apps.uqo.ca/LoginSigparb/LoginPourRessources.aspx?url=http://www.deslibris.ca/ID/10091391″,”ISBN”:”978-3-9818107-0-7″,”note”:”OCLC: 1010981965″,”language”:”English”,”author”:{“family”:”Zervos”,”given”:”Arthouros”},{“family”:”Lins”,”given”:”Christine”},”issued”:{“date-parts”:”2017″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 9. In 2015, the installed capacity of ST collectors grew by 6,3% (26 GWth) which is a significant growth reduction from previous years. As a comparison point, the installed capacity of PV is breaking record as it grew by 28% which corresponds to 50 GW ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a12pejrrdqc”,”properties”:{“formattedCitation”:”5″,”plainCitation”:”5″,”noteIndex”:0},”citationItems”:{“id”:15,”uris”:”http://zotero.org/users/4612010/items/54WRGLFE”,”uri”:”http://zotero.org/users/4612010/items/54WRGLFE”,”itemData”:{“id”:15,”type”:”book”,”title”:”Renewables 2016 Global Status Report”,”source”:”Open WorldCat”,”URL”:”https://apps.uqo.ca/LoginSigparb/LoginPourRessources.aspx?url=http://www.deslibris.ca/ID/10091391″,”ISBN”:”978-3-9818107-0-7″,”note”:”OCLC: 1010981965″,”language”:”English”,”author”:{“family”:”Zervos”,”given”:”Arthouros”},{“family”:”Lins”,”given”:”Christine”},”issued”:{“date-parts”:”2016″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 5.

As shown in the figures 5 and 6, over the last 10 years, ST total installed capacity has roughly quadrupled while PV has been multiplied a factor 45. However, although there is a difference of an order of magnitude between these two numbers, it is important to point out that PV started with a much lower base number from which it was easier to increase. Both figures show how China is currently dominating the solar market.

Figure SEQ Figure * ARABIC 7: Installed capacity of ST in the top 20 countries in 2015 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”WvQWmVQM”,”properties”:{“formattedCitation”:”15″,”plainCitation”:”15″,”noteIndex”:0},”citationItems”:{“id”:142,”uris”:”http://zotero.org/users/4612010/items/N5BM3IVW”,”uri”:”http://zotero.org/users/4612010/items/N5BM3IVW”,”itemData”:{“id”:142,”type”:”report”,”title”:”Solar Heat Worldwide, IEA Solar Heating ; Cooling Programme”,”publisher”:”AEE INSTEC, Austria”,”author”:{“literal”:”Spork-dur, Monika”},{“family”:”Mauthner”,”given”:”Franz”},”issued”:{“date-parts”:”2017″}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 15
Finally, it is important to refer that the heat produced by ST can serve different purposes, as show in the figure below. In the world, domestic hot water production either for single or multi family houses is the main application for ST, although some economic regions install ST for different purposes.

Figure SEQ Figure * ARABIC 8: Solar Thermal Applications by economic region in 2015 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”2VORcffk”,”properties”:{“formattedCitation”:”15″,”plainCitation”:”15″,”noteIndex”:0},”citationItems”:{“id”:142,”uris”:”http://zotero.org/users/4612010/items/N5BM3IVW”,”uri”:”http://zotero.org/users/4612010/items/N5BM3IVW”,”itemData”:{“id”:142,”type”:”report”,”title”:”Solar Heat Worldwide, IEA Solar Heating ; Cooling Programme”,”publisher”:”AEE INSTEC, Austria”,”author”:{“literal”:”Spork-dur, Monika”},{“family”:”Mauthner”,”given”:”Franz”},”issued”:{“date-parts”:”2017″}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 15
Basics of Solar Energy: Differences between PV and STThe effect of solar radiation in PV and ST collectorsThe REF _Ref505272258 h * MERGEFORMAT Figure 9 shows the effect of solar radiation on both power and efficiency for photovoltaics panels and solar thermal collectors, which is calculated according to a simplified model using the following formulas:
Photovoltaic panels: P=I?? (eq. 1)
Solar thermal collectors:P=?0?I-(U1+U2? ?T? ?T) (eq. 2)
where P is the power from the collector, I is the irradiance on the plane, ? is the efficiency of the collector, ?0 is the optical efficiency of the thermal collector, U1 is the first order heat losses and U2 is the second order heat losses.

In equation 2, the heat loss value (U) is already including both components U1 and U2. Figure 1 shows a graphical representation of the above formulae.

A B
Figure SEQ Figure * ARABIC 9: The impact of solar radiation on power (A) and efficiency (B) for PV and T collectors at a ?T of 50°C IThe collector values used to plot the above graphs were taken from a market survey which is shown in the result section. These efficiencies values represent standard thermal collector calculated based on the aperture area of collectors working a ?T = (Tmed – Tambient) = 50°C, where Tmed = (Tin + Tout) / 2. In this model, only the most relevant factors are taken in consideration. In reality, there are other factors to consider, such as the fact the efficiency of a crystalline solar cell is reduced at lower radiation levels ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a9c5kap7an”,”properties”:{“formattedCitation”:”16″,”plainCitation”:”16″,”noteIndex”:0},”citationItems”:{“id”:36,”uris”:”http://zotero.org/users/4612010/items/VYPQLQCE”,”uri”:”http://zotero.org/users/4612010/items/VYPQLQCE”,”itemData”:{“id”:36,”type”:”book”,”title”:”Solar Cells: Operating Principles, Technology, and System Applications”,”publisher”:”Prentice Hall”,”publisher-place”:”Englewood Cliffs, NJ”,”number-of-pages”:”274″,”source”:”Amazon”,”event-place”:”Englewood Cliffs, NJ”,”abstract”:”Prentice hall series”,”ISBN”:”978-0-13-822270-3″,”shortTitle”:”Solar Cells”,”language”:”English”,”author”:{“family”:”Green”,”given”:”Martin A.”},”issued”:{“date-parts”:”1981″,10,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 16 or that an increase in the temperature of the solar cells will lead to a decrease in solar cell efficiency of around -0,44 %/ºK for mono crystalline solar cells ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”ancebvpovp”,”properties”:{“formattedCitation”:”17″,”plainCitation”:”17″,”noteIndex”:0},”citationItems”:{“id”:30,”uris”:”http://zotero.org/users/4612010/items/D73L8ZG7″,”uri”:”http://zotero.org/users/4612010/items/D73L8ZG7″,”itemData”:{“id”:30,”type”:”book”,”title”:”Photovoltaik Engineering – Handbuch für Planung, Entwicklung | Andreas Wagner | Springer”,”source”:”www.springer.com”,”abstract”:”Erweitert durch die Steuerung von nachgeführten Anlagen und den Energieertragsgewinn durch Nachführung Hilft bei der Auslegung von Anlagen unter…”,”URL”:”//www.springer.com/de/book/9783662486399″,”language”:”en”,”author”:{“family”:”Wagner”,”given”:””},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 17. However, the point that is made by the above figure is that, at a constant temperature, the efficiency of a PV-system is almost independent of the solar irradiance, while the efficiency of solar thermal-systems is strongly dependent. The efficiency of a thermal collector is often zero at low solar radiation intensities.

System losses such as inverters, cabling, or piping were not considered neither for ST nor for PV.

The effect of temperature in PV and T collectors REF _Ref505277885 h * MERGEFORMAT Figure 10 shows the effect of operating temperature on the efficiency of the solar panels which was calculated using the formulas 1 and 2. For the PV panels, the cell temperature dependency was taken into account as described below.

Figure SEQ Figure * ARABIC 10: The impact of temperature in efficiency of PV & ST panels at a constant solar radiation of 1000W/m2 IAs mentioned in the author´s paper I, the operational temperature of a PV panel varies according to how much solar radiation is received and how much heat the panel is able to lose, which is greatly influenced by factors like panel construction or type of installation (building integrated vs free standing). The operating temperature of a PV panel is defined by the nominal operating cell temperature (NOCT). For this graph, it was accepted that 120ºC was the maximum temperature for the PV panel since many panels break after that temperature ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”aqh7v19k5k”,”properties”:{“formattedCitation”:”18″,”plainCitation”:”18″,”noteIndex”:0},”citationItems”:{“id”:38,”uris”:”http://zotero.org/users/4612010/items/KYQX6UCB”,”uri”:”http://zotero.org/users/4612010/items/KYQX6UCB”,”itemData”:{“id”:38,”type”:”book”,”title”:”Applied Photovoltaics”,”publisher”:”Routledge”,”publisher-place”:”London ; Sterling, VA”,”number-of-pages”:”330″,”edition”:”2nd edition”,”source”:”Amazon”,”event-place”:”London ; Sterling, VA”,”abstract”:”A reliable, accessible and comprehensive guide for students of photovoltaic applications and renewable energy engineering. This thoroughly considered textbook from a group of leading influential and award-winning authors is brimming with information and is carefully designed to meet the needs of its readers. Along with exercises and references at the end of each chapter, the book features a set of detailed technical appendices that provide essential equations, data sources and standards. Starting from basics with ‘The Characteristics of Sunlight’ the reader is guided step-by-step through semiconductors and p-n junctions; the behaviour of solar cells; cell properties ad design; and PV cell interconnection and module fabrication. The book covers stand-alone photovoltaic systems; specific purpose photovoltaic systems; remote are power supply systems; and grid-connected photovoltaic systems. There is also a section on photovoltaic water pumping system components and design. Applied Photovolatics is well illustrated and readable with an abundance of diagrams and illustrations, and will provide the reader with all the information needed to start working with photovoltaics.”,”ISBN”:”978-1-84407-401-3″,”language”:”English”,”editor”:{“family”:”Wenham”,”given”:”Stuart R.”},{“family”:”Green”,”given”:”Martin A.”},{“family”:”Watt”,”given”:”Muriel E.”},{“family”:”Corkish”,”given”:”Richard”},”issued”:{“date-parts”:”2006″,12,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 18. Just like for PV panels, the operational temperature of an ST collector is also a function of solar radiation and heat losses although in ST systems a fluid is extracting heat from collector. This fluid can be water, glycol or a special type of oil for collectors that work at very high temperatures. The amount of heat that is carried away by the fluid temperature depends on factors such as the temperature difference between the fluid and the collector, the ambient temperature, the characteristics of the fluid and the speed and type of flow ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a8fscrm5g4″,”properties”:{“formattedCitation”:”19″,”plainCitation”:”19″,”noteIndex”:0},”citationItems”:{“id”:40,”uris”:”http://zotero.org/users/4612010/items/YA2XS89Z”,”uri”:”http://zotero.org/users/4612010/items/YA2XS89Z”,”itemData”:{“id”:40,”type”:”chapter”,”title”:”Solar Engineering of Thermal Processes”,”container-title”:”Solar Engineering of Thermal Processes”,”publisher”:”John Wiley ; Sons, Inc.”,”page”:”i-xxvi”,”source”:”Wiley Online Library”,”abstract”:”The prelims comprise:

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Half Title

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Copyright

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Contents

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Preface

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Preface to the Third Edition

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Preface to the Second Edition

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Preface to the First Edition

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Introduction”,”URL”:”http://onlinelibrary.wiley.com/doi/10.1002/9781118671603.fmatter/summary”,”ISBN”:”978-1-118-67160-3″,”note”:”DOI: 10.1002/9781118671603.fmatter”,”language”:”en”,”author”:{“family”:”Duffie”,”given”:”John A.”},{“family”:”Beckman”,”given”:”William A.”},”issued”:{“date-parts”:”2013″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 19.

A major difference between PV and ST panels is that, in ST panels, the heat is carried from the collector to the tank, while in standard PV panels the built up of heat is passively dissipated. A similarity of both types of panels is that the efficiency goes up when the operating temperature is decreased.

Influencing factors: local climateWeather conditions widely vary around the globe. An example from paper I shows the variation of beam radiation around the world while REF _Ref505849429 h * MERGEFORMAT figure 2 shows the annual average temperature. Many other parameters, such as the median daily variation of temperature or the air humidity could be shown to illustrate these large variations. The numbers in REF _Ref505849376 h * MERGEFORMAT figure 11 show the percentage of beam radiation in the total solar radiation normal to the ground, while the color shows the total amount of solar radiation. As recognizable in the figure, the beam fraction is not dependent on the latitude although the total amount of solar radiation generally increases at lower latitudes. The main influence on the beam fraction is the local climate ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a1k4jvurvqu”,”properties”:{“formattedCitation”:”20″,”plainCitation”:”20″,”noteIndex”:0},”citationItems”:{“id”:”TU1l2kdv/2bSQhJcl”,”uris”:”http://zotero.org/users/4612010/items/3I9R4B48″,”uri”:”http://zotero.org/users/4612010/items/3I9R4B48″,”itemData”:{“id”:43,”type”:”webpage”,”title”:”Physics of Solar Energy”,”container-title”:”Wiley.com”,”abstract”:”The definitive guide to the science of solar energy You hold in your hands the first, and only, truly comprehensive guide to the most abundant and most promising source of alternative energy—solar power. In recent years, all major countries in the world have been calling for an energy revolution. The renewable energy industry will drive a vigorous expansion of the global economy and create more green jobs. The use of fossil fuels to power our way of living is moving toward an inevitable end, with sources of coal, petroleum, and natural gas being fiercely depleted. Solar energy offers a ubiquitous, inexhaustible, clean, and highly efficient way of meeting the energy needs of the twenty-first century. This book is designed to give the reader a solid footing in the general and basic physics of solar energy, which will be the basis of research and development in new solar engineering technologies in the years to come. As solar technologies like solar cells, solar thermal power generators, solar water heaters, solar photochemistry applications, and solar space heating-cooling systems become more and more prominent, it has become essential that the next generation of energy experts—both in academia and industry—have a one-stop resource for learning the basics behind the science, applications, and technologies afforded by solar energy. This book fills that need by laying the groundwork for the projected rapid expansion of future solar projects.”,”URL”:”https://www.wiley.com/en-us/Physics+of+Solar+Energy-p-9780470647806″,”language”:”en_US”,”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 20.

Figure SEQ Figure * ARABIC 11: Percentage of beam in the total solar radiation (number) and total solar radiation in different locations (color) IThe percentage of beam radiation in the total radiation ranges from 43% in Singapore to 77% in El Paso and Tamanrasset. Singapore, Naha, Chon Buri, Manaus and Bergen are the only five cities where the diffuse radiation represents more than 50% of the annual solar radiation received in the ground. The main reason for this effect is the presence of clouds 5. Cities in Southeast Asia are affected by the monsoon, twice a year. Bergen has 200 rainy days over the year and a moderate climate 10. Manaus, located close to the equator, is affected by a long rainy season which leads to the 48% of beam in the total solar radiation. Whereas in desert areas like El Paso or Tamanrasset, the climate is dry and the ratio reaches up to 77%. As expected, the countries closer to the equator show the warmest average temperatures around the world which go up to 30°C. However, there are exceptions like La Paz with 8,2ºC which owes its low annual temperature to the high altitude. At high altitudes, the layer of atmosphere is less dense which leads to both higher temperature variations (the atmosphere has less capacity of retaining the heat) and higher solar radiation (the atmosphere is less dense and absorbs less solar radiation). The main cause of low temperatures at higher latitudes is the angle at which the incoming rays hit the ground. Although, the normal solar radiation in a perfect sunny day is close to 1000W/m2 anywhere in the world at sea level, if the sunlight has a lower angle, that sunlight will be spread over a larger area. This effect is also known as the cosine effect ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a1buqa7fgca”,”properties”:{“formattedCitation”:”21″,”plainCitation”:”21″,”noteIndex”:0},”citationItems”:{“id”:47,”uris”:”http://zotero.org/users/4612010/items/7ZW9THA2″,”uri”:”http://zotero.org/users/4612010/items/7ZW9THA2″,”itemData”:{“id”:47,”type”:”webpage”,”title”:”Physics of Solar Energy”,”container-title”:”Wiley.com”,”abstract”:”The definitive guide to the science of solar energy You hold in your hands the first, and only, truly comprehensive guide to the most abundant and most promising source of alternative energy—solar power. In recent years, all major countries in the world have been calling for an energy revolution. The renewable energy industry will drive a vigorous expansion of the global economy and create more green jobs. The use of fossil fuels to power our way of living is moving toward an inevitable end, with sources of coal, petroleum, and natural gas being fiercely depleted. Solar energy offers a ubiquitous, inexhaustible, clean, and highly efficient way of meeting the energy needs of the twenty-first century. This book is designed to give the reader a solid footing in the general and basic physics of solar energy, which will be the basis of research and development in new solar engineering technologies in the years to come. As solar technologies like solar cells, solar thermal power generators, solar water heaters, solar photochemistry applications, and solar space heating-cooling systems become more and more prominent, it has become essential that the next generation of energy experts—both in academia and industry—have a one-stop resource for learning the basics behind the science, applications, and technologies afforded by solar energy. This book fills that need by laying the groundwork for the projected rapid expansion of future solar projects.”,”URL”:”https://www.wiley.com/en-us/Physics+of+Solar+Energy-p-9780470647806″,”language”:”en_US”,”author”:{“family”:”Chen”,”given”:”J”},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 21.

Figure SEQ Figure * ARABIC 12: Annual average temperature of 66 cities around the globeLocations with the same annual temperature may present very different temperature profiles. For example, Lisbon and El Paso have similar annual temperatures around 17ºC but when comparing the daily profile, it can be found that the temperature is steady in Lisbon, a coastal city with a Subtropical-Mediterranean climate while El Paso has large variations over 24 hours and a hot desert climate. Another example is the climate on the West Coast of Europe is much milder than the climate in the interior of Europe at the same latitude. This is due to the effect of the Gulf Stream that not only warms up the air but also stabilizes its temperature ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a2g81vair0u”,”properties”:{“formattedCitation”:”22″,”plainCitation”:”22″,”noteIndex”:0},”citationItems”:{“id”:49,”uris”:”http://zotero.org/users/4612010/items/Z8XDGMKZ”,”uri”:”http://zotero.org/users/4612010/items/Z8XDGMKZ”,”itemData”:{“id”:49,”type”:”book”,”title”:”Understanding Weather and Climate, Third Edition”,”publisher”:”Prentice Hall”,”publisher-place”:”Upper Saddle River, N.J”,”number-of-pages”:”592″,”edition”:”3 edition”,”source”:”Amazon”,”event-place”:”Upper Saddle River, N.J”,”abstract”:”This meteorology book focuses on explanation about the processes that produce Earth’s weather and climate. It emphasizes a non-mathematical understanding of physical principles as a vehicle for learning about atmospheric processes. Additionally, difficult-to-visualize topics are reinforced with a series of software tutorials presented on a CD-ROM packaged with the book. Accompanying CD-ROM is available featuring Tutorials, Interactive Exercises, and illustrative movie loops all keyed to the book. Also, this book includes up-to-date coverage of severe weather events For professionals in the meteorology field.”,”ISBN”:”978-0-13-101582-1″,”language”:”English”,”author”:{“family”:”Aguado”,”given”:”Edward”},{“family”:”Burt”,”given”:”James E.”},{“family”:”Burt”,”given”:”James”},”issued”:{“date-parts”:”2003″,6,24}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 22.

Basics of Concentration in Solar CollectorsConcentrating collectors have the ability to re-direct solar radiation that passes through an aperture into the receiver or absorber. The goal is to reach a better ratio of €/kWh of heat and/or electricity produced. These collectors sometimes include also a tracking system in order to maximize the energy yield ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”av7rt94amn”,”properties”:{“formattedCitation”:”23″,”plainCitation”:”23″,”noteIndex”:0},”citationItems”:{“id”:53,”uris”:”http://zotero.org/users/4612010/items/ZGITLAZL”,”uri”:”http://zotero.org/users/4612010/items/ZGITLAZL”,”itemData”:{“id”:53,”type”:”article-journal”,”title”:”Concentrated photovoltaic thermal (CPVT) solar collector systems: Part I – Fundamentals, design considerations and current technologies”,”container-title”:”Renewable and Sustainable Energy Reviews”,”page”:”1500-1565″,”volume”:”50″,”issue”:”Supplement C”,”source”:”ScienceDirect”,”abstract”:”Concentrated photovoltaic thermal (CPVT) solar collectors have been gaining ever-increasing attention from the scientific community and industrial developers due to their promising potential to pave the way for the penetration of solar energy into modern day power generation technologies. CPVTs? flexibility, manufacturability, high efficiency, and multi-output nature inspired many innovative designs and design improvements available in the literature. In this study, a comprehensive, up-to-date review of the governing scientific basics, system variations, and technological advances in CPVT systems will be presented. The study is split into two parts. The first part covers CPVTs? characteristics and design considerations in addition to a review of the principals and technological advances in the solar components that compose a CPVT (i.e., photovoltaic cells, solar thermal collectors, concentrator optics, tracking mechanisms, concentrated photovoltaics, and concentrated solar thermal systems). While the second part thoroughly covers CPVTs? published studies, application areas, performance assessment, commercial initiatives, and research prospects.”,”DOI”:”10.1016/j.rser.2015.05.036″,”ISSN”:”1364-0321″,”shortTitle”:”Concentrated photovoltaic thermal (CPVT) solar collector systems”,”journalAbbreviation”:”Renewable and Sustainable Energy Reviews”,”author”:{“family”:”Sharaf”,”given”:”Omar Z.”},{“family”:”Orhan”,”given”:”Mehmet F.”},”issued”:{“date-parts”:”2015″,10,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 23.

Concentration designs vary greatly from low concentration non tracking design to large concentrated solar power (CSP) plants with extremely high concentration factors. Depending on the type of concentration, concentrating collectors are often categorized in two types: high or low concentration.
The low concentration can be subdivided into three different types: (i) Booster reflector; (ii) Compound Parabolic Concentrator (CPC); (iii) Luminescent Concentrator ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a2mfeosdj3i”,”properties”:{“formattedCitation”:”24″,”plainCitation”:”24″,”noteIndex”:0},”citationItems”:{“id”:51,”uris”:”http://zotero.org/users/4612010/items/LHLAWWNU”,”uri”:”http://zotero.org/users/4612010/items/LHLAWWNU”,”itemData”:{“id”:51,”type”:”book”,”title”:”Renewable Energy: Power for a Sustainable Future”,”publisher”:”Oxford University Press”,”publisher-place”:”Oxford”,”number-of-pages”:”566″,”edition”:”3 edition”,”source”:”Amazon”,”event-place”:”Oxford”,”abstract”:”The provision of sustainable energy supplies for an expanding and increasingly productive world is one of the major issues facing civilization today. Renewable Energy: Power for a Sustainable Future, Third Edition, examines both the practical and economic potential of the renewable energy sources to meet this challenge. The underlying physical and technological principles behind deriving power from direct solar (solar thermal and photovoltaics), indirect solar (biomass, hydro, wind, and wave) and non-solar (tidal and geothermal) energy sources are explained, within the context of their environmental impacts, their economics, and their future prospects.Together with its companion volume, Energy Systems and Sustainability, Second Edition (OUP, 2012, 9780199593743), this book provides both perspective and detail on the relative merits and state of progress of technologies for utilizing the various “renewables.” The analysis considers emissions, sustainability, cost implications, and energy security, as political and economic pressures move society towards a low-carbon future. From an overview of basic energy conversion processes to a discussion of the individual renewable sources to a concluding examination of the prospects for their integration into national and international networks, Renewable Energy: Power for a Sustainable Future, Third Edition, provides a valuable insight into prospects for the renewables.FEATURESCovers all principal sources of renewable energy currently being exploitedUses an interdisciplinary approach in considering economic, social, environmental, and policy issuesRich pedagogy including detailed color illustrations and tables of dataCOMPANION WEBSITE (www.oup.com/uk/orc/bin/9780199545339)For students: Self-assessment questions and links to further information and up-to-date energy statisticsFor instructors: Figures from the book in electronic format (available to registered adopters of the book)”,”ISBN”:”978-0-19-954533-9″,”shortTitle”:”Renewable Energy”,”language”:”English”,”author”:{“family”:”Boyle”,”given”:”Godfrey”},”issued”:{“date-parts”:”2012″,11,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 24 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a1ml9d75mdi”,”properties”:{“formattedCitation”:”23″,”plainCitation”:”23″,”noteIndex”:0},”citationItems”:{“id”:53,”uris”:”http://zotero.org/users/4612010/items/ZGITLAZL”,”uri”:”http://zotero.org/users/4612010/items/ZGITLAZL”,”itemData”:{“id”:53,”type”:”article-journal”,”title”:”Concentrated photovoltaic thermal (CPVT) solar collector systems: Part I – Fundamentals, design considerations and current technologies”,”container-title”:”Renewable and Sustainable Energy Reviews”,”page”:”1500-1565″,”volume”:”50″,”issue”:”Supplement C”,”source”:”ScienceDirect”,”abstract”:”Concentrated photovoltaic thermal (CPVT) solar collectors have been gaining ever-increasing attention from the scientific community and industrial developers due to their promising potential to pave the way for the penetration of solar energy into modern day power generation technologies. CPVTs? flexibility, manufacturability, high efficiency, and multi-output nature inspired many innovative designs and design improvements available in the literature. In this study, a comprehensive, up-to-date review of the governing scientific basics, system variations, and technological advances in CPVT systems will be presented. The study is split into two parts. The first part covers CPVTs? characteristics and design considerations in addition to a review of the principals and technological advances in the solar components that compose a CPVT (i.e., photovoltaic cells, solar thermal collectors, concentrator optics, tracking mechanisms, concentrated photovoltaics, and concentrated solar thermal systems). While the second part thoroughly covers CPVTs? published studies, application areas, performance assessment, commercial initiatives, and research prospects.”,”DOI”:”10.1016/j.rser.2015.05.036″,”ISSN”:”1364-0321″,”shortTitle”:”Concentrated photovoltaic thermal (CPVT) solar collector systems”,”journalAbbreviation”:”Renewable and Sustainable Energy Reviews”,”author”:{“family”:”Sharaf”,”given”:”Omar Z.”},{“family”:”Orhan”,”given”:”Mehmet F.”},”issued”:{“date-parts”:”2015″,10,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 23 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a1vaikoj7g9″,”properties”:{“formattedCitation”:”25″,”plainCitation”:”25″,”noteIndex”:0},”citationItems”:{“id”:55,”uris”:”http://zotero.org/users/4612010/items/8F5RQ4SL”,”uri”:”http://zotero.org/users/4612010/items/8F5RQ4SL”,”itemData”:{“id”:55,”type”:”article-journal”,”title”:”Design and development of compound parabolic concentrating for photovoltaic solar collector: Review”,”container-title”:”Renewable and Sustainable Energy Reviews”,”page”:”1108-1121″,”volume”:”76″,”source”:”ukm.pure.elsevier.com”,”DOI”:”10.1016/j.rser.2017.03.127″,”ISSN”:”1364-0321″,”shortTitle”:”Design and development of compound parabolic concentrating for photovoltaic solar collector”,”journalAbbreviation”:”Renewable & sustainable energy reviews, Renewable and sustainable energy reviews, Reupdateable and Sustainable Energy Reviews”,”language”:”English”,”author”:{“family”:”Jaaz”,”given”:”Ahed Hameed”},{“family”:”Hasan”,”given”:”Husam Abdulrasool”},{“family”:”Sopian”,”given”:”Kamaruzzaman”},{“family”:”Ruslan”,”given”:”Mohd Hafidz Bin Haji”},{“family”:”Zaidi”,”given”:”Saleem Hussain”},”issued”:{“date-parts”:”2017″,9,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 25 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a1h81ttp6v6″,”properties”:{“formattedCitation”:”26″,”plainCitation”:”26″,”noteIndex”:0},”citationItems”:{“id”:57,”uris”:”http://zotero.org/users/4612010/items/PKKKSXQ9″,”uri”:”http://zotero.org/users/4612010/items/PKKKSXQ9″,”itemData”:{“id”:57,”type”:”article-journal”,”title”:”Optical and thermal characterization of a variable geometry concentrator using ray-tracing tools and experimental data”,”container-title”:”Applied Energy”,”page”:”110–119″,”volume”:”155″,”source”:”Google Scholar”,”author”:{“family”:”Pujol-Nadal”,”given”:”Ramon”},{“family”:”Martínez-Moll”,”given”:”Víctor”},{“family”:”Sallaberry”,”given”:”Fabienne”},{“family”:”Moià-Pol”,”given”:”Andreu”},”issued”:{“date-parts”:”2015″}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 26. The following figure shows the high concentration technologies currently available.

Figure SEQ Figure * ARABIC 13: Four technologies for high concentration solar energy. Linear concentrators: Trough (a) and Fresnel (b). Punctual concentrators: Tower (c) and Dish (d) ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a1bkpjit2g7″,”properties”:{“formattedCitation”:”27″,”plainCitation”:”27″,”noteIndex”:0},”citationItems”:{“id”:68,”uris”:”http://zotero.org/users/4612010/items/AY6A7CG5″,”uri”:”http://zotero.org/users/4612010/items/AY6A7CG5″,”itemData”:{“id”:68,”type”:”webpage”,”title”:”DIW Berlin: Holding a Candle to Innovation in Concentrating Solar Power Technologies : A Study Drawing on Patent Data”,”genre”:”Text”,”URL”:”https://www.diw.de/sixcms/detail.php?id=diw_01.c.371611.de”,”shortTitle”:”DIW Berlin”,”language”:”de”,”author”:{“family”:”Braun”,”given”:”Frauke G.”},{“family”:”Hooper”,”given”:”Elizabeth”},{“family”:”Wand”,”given”:”Robert”},{“family”:”Zlocytsti”,”given”:”Petra”},”issued”:{“date-parts”:”2007″,3,1},”accessed”:{“date-parts”:”2018″,1,17}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 27
Concentration factorThe concentration factor (Ci) is one of the most important parameters for concentrators. It is defined as the ratio between the effective area of the aperture and the area of the receiver.

Ci = Aperture AreaReceiver Area(e.q. 7)
A collector with no concentration is said to have a concentration factor of 1, while a collector that has an aperture (Aa) that is twice the receiver area (Ar) is said to have a concentration factor of 2 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a1f0a1f4ar3″,”properties”:{“formattedCitation”:”25″,”plainCitation”:”25″,”noteIndex”:0},”citationItems”:{“id”:55,”uris”:”http://zotero.org/users/4612010/items/8F5RQ4SL”,”uri”:”http://zotero.org/users/4612010/items/8F5RQ4SL”,”itemData”:{“id”:55,”type”:”article-journal”,”title”:”Design and development of compound parabolic concentrating for photovoltaic solar collector: Review”,”container-title”:”Renewable and Sustainable Energy Reviews”,”page”:”1108-1121″,”volume”:”76″,”source”:”ukm.pure.elsevier.com”,”DOI”:”10.1016/j.rser.2017.03.127″,”ISSN”:”1364-0321″,”shortTitle”:”Design and development of compound parabolic concentrating for photovoltaic solar collector”,”journalAbbreviation”:”Renewable & sustainable energy reviews, Renewable and sustainable energy reviews, Reupdateable and Sustainable Energy Reviews”,”language”:”English”,”author”:{“family”:”Jaaz”,”given”:”Ahed Hameed”},{“family”:”Hasan”,”given”:”Husam Abdulrasool”},{“family”:”Sopian”,”given”:”Kamaruzzaman”},{“family”:”Ruslan”,”given”:”Mohd Hafidz Bin Haji”},{“family”:”Zaidi”,”given”:”Saleem Hussain”},”issued”:{“date-parts”:”2017″,9,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 25. Designs with higher concentrations require tracking the sun, while low concentration designs may dispense tracking. Tracking increases the amount of solar irradiation that reaches the receiver but also increases cost, complexity and may not suitable all locations.
Ideal two-dimensional (linear) non-truncated CPC with an acceptance half angle ?c has a maximum concentration factor that is given by the following equation ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”acb32lu92p”,”properties”:{“formattedCitation”:”28″,”plainCitation”:”28″,”noteIndex”:0},”citationItems”:{“id”:73,”uris”:”http://zotero.org/users/4612010/items/EUGSFNGP”,”uri”:”http://zotero.org/users/4612010/items/EUGSFNGP”,”itemData”:{“id”:73,”type”:”book”,”title”:”High Collection Nonimaging Optics – 1st Edition”,”publisher”:”Academic Press”,”URL”:”https://www.elsevier.com/books/high-collection-nonimaging-optics/welford/978-0-12-742885-7″,”author”:{“family”:”Winston”,”given”:”R.”},{“family”:”Welford”,”given”:”W.T.”},”accessed”:{“date-parts”:”2018″,1,17}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 28 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a26a6her1hh”,”properties”:{“formattedCitation”:”19″,”plainCitation”:”19″,”noteIndex”:0},”citationItems”:{“id”:40,”uris”:”http://zotero.org/users/4612010/items/YA2XS89Z”,”uri”:”http://zotero.org/users/4612010/items/YA2XS89Z”,”itemData”:{“id”:40,”type”:”chapter”,”title”:”Solar Engineering of Thermal Processes”,”container-title”:”Solar Engineering of Thermal Processes”,”publisher”:”John Wiley & Sons, Inc.”,”page”:”i-xxvi”,”source”:”Wiley Online Library”,”abstract”:”The prelims comprise:

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Introduction”,”URL”:”http://onlinelibrary.wiley.com/doi/10.1002/9781118671603.fmatter/summary”,”ISBN”:”978-1-118-67160-3″,”note”:”DOI: 10.1002/9781118671603.fmatter”,”language”:”en”,”author”:{“family”:”Duffie”,”given”:”John A.”},{“family”:”Beckman”,”given”:”William A.”},”issued”:{“date-parts”:”2013″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 19:
Ci = 1Sin(?c) sin (2.6)
Compound Parabolic CollectorsThis thesis work will focus on CPC´s, which is a non-imaging type of concentrators that does not necessarily require a tracking system due to the ability of reflecting both beam and diffuse radiation to the receiver. The incidence angle for these concentrators makes them very attractive from the point of view of system simplicity, flexibility and cost effectiveness ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a111to1bld2″,”properties”:{“formattedCitation”:”28″,”plainCitation”:”28″,”noteIndex”:0},”citationItems”:{“id”:73,”uris”:”http://zotero.org/users/4612010/items/EUGSFNGP”,”uri”:”http://zotero.org/users/4612010/items/EUGSFNGP”,”itemData”:{“id”:73,”type”:”book”,”title”:”High Collection Nonimaging Optics – 1st Edition”,”publisher”:”Academic Press”,”URL”:”https://www.elsevier.com/books/high-collection-nonimaging-optics/welford/978-0-12-742885-7″,”author”:{“family”:”Winston”,”given”:”R.”},{“family”:”Welford”,”given”:”W.T.”},”accessed”:{“date-parts”:”2018″,1,17}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 28 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”aemn40pn18″,”properties”:{“formattedCitation”:”29″,”plainCitation”:”29″,”noteIndex”:0},”citationItems”:{“id”:71,”uris”:”http://zotero.org/users/4612010/items/XQPWU6FF”,”uri”:”http://zotero.org/users/4612010/items/XQPWU6FF”,”itemData”:{“id”:71,”type”:”book”,”title”:”Solar Thermal Collectors at High Latitudes Design and Performance of Non-Tracking Concentrators”,”publisher”:”Uppsala University”,”volume”:”PhD Thesis”,”source”:”ResearchGate”,”abstract”:”ABSTRACT Adsten, M. 2002. Solar thermal collectors at high latitudes -Design and performance of non- tracking concentrators. Acta Universitatis Upsaliensis. Comprehensive,Summaries of Uppsala Dissertations from the Facultyof Science and Technology 697. 78 pp. Uppsala. ISBN 91-554- 5274-4 Solar thermal collectors at high latitudes have been studied, with emphasis on concentrating collectors. A novel design of concentrating collector, the Maximum Reflector Collector (MaReCo), especially designed for high latitudes, has been investigated optically and thermally. The MaReCo is an asymmetrical,compound,parabolic concentrator with a bi-facial absorber. The collector can be adapted to various installation conditions, for example stand- alone, roof- or wall mounted. MaReCo prototypes have been built and outdoor-tested. The evaluation showed ,that all types work ,as expected ,and that the highest annually delivered energy output, 340 kWh/m,, is found for the roof MaReCo. A study of the heat-losses from the stand-alone MaReCo lead to the conclusion that ,teflon transparent insulation should be placed around the absorber, which decreases the U-value by about 30%. A method was developed to theoreticallystudy the projected radiation distribution incident onthe,MaReCo bi-facial absorber. The study showed ,that the geometry ,of the ,collectors could be improved ,by slight ,changes in the ,acceptance intervals. It also indicated that the MaReCo design concept could be used ,also at mid-European ,latitudes if the geometry ,is changed. Anovel,method ,was ,used to perform ,outdoor measurements ,of the ,distribution of concentrated light on the ,absorber and then to calculate ,the annually collected ,zero-loss energy, Ea,corr, together with the annual optical efficiency factor. A study using this method indicated that the absorber should be mounted,along the 20° optical axis instead of along,the”,”author”:{“family”:”Adsten”,”given”:”Monika”},”issued”:{“date-parts”:”2002″,1,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 29 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a2h2h9o6121″,”properties”:{“formattedCitation”:”30″,”plainCitation”:”30″,”noteIndex”:0},”citationItems”:{“id”:101,”uris”:”http://zotero.org/users/4612010/items/PJ2YEBWX”,”uri”:”http://zotero.org/users/4612010/items/PJ2YEBWX”,”itemData”:{“id”:101,”type”:”thesis”,”title”:”A solar concentrating photovoltaic/thermal collector”,”publisher”:”The Australian National University”,”source”:”openresearch-repository.anu.edu.au”,”abstract”:”This thesis discusses aspects of a novel solar concentrating photovoltaic / thermal (PV/T) collector that has been designed to produce both electricity and hot water. The motivation for the development of the Combined Heat and Power Solar (CHAPS) collector is twofold: in the short term, to produce photovoltaic power and solar hot water at a cost which is competitive with other renewable energy technologies, and in the longer term, at a cost which is lower than possible with current technologies. To the author’s knowledge, the CHAPS collector is the first PV/T system using a reflective linear concentrator with a concentration ratio in the range 20-40x. The work contained in this thesis is a thorough study of all facets of the CHAPS collector, through a combination of theoretical and experimental investigation. …”,”URL”:”https://openresearch-repository.anu.edu.au/handle/1885/46253″,”language”:”en”,”author”:{“family”:”Coventry”,”given”:”Joseph S.”},”issued”:{“date-parts”:”2004″,6},”accessed”:{“date-parts”:”2018″,1,17}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 30. CPC concentrators are combining two parabolic reflectors that can be symmetric or asymmetric. Each reflector has its own focus length (F) at the lower edge of the other parabola, as shown in the figure on the right side.

4020354765175Figure SEQ Figure * ARABIC 14: Cross section of a symmetrical non-truncated CPC ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”ah5iuh3obg”,”properties”:{“formattedCitation”:”15″,”plainCitation”:”15″},”citationItems”:{“id”:40,”uris”:”http://zotero.org/users/4612010/items/YA2XS89Z”,”uri”:”http://zotero.org/users/4612010/items/YA2XS89Z”,”itemData”:{“id”:40,”type”:”chapter”,”title”:”Frontmatter”,”container-title”:”Solar Engineering of Thermal Processes”,”publisher”:”John Wiley ; Sons, Inc.”,”page”:”i-xxvi”,”source”:”Wiley Online Library”,”abstract”:”The prelims comprise:

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Figure SEQ Figure * ARABIC 14: Cross section of a symmetrical non-truncated CPC ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”ah5iuh3obg”,”properties”:{“formattedCitation”:”15″,”plainCitation”:”15″},”citationItems”:{“id”:40,”uris”:”http://zotero.org/users/4612010/items/YA2XS89Z”,”uri”:”http://zotero.org/users/4612010/items/YA2XS89Z”,”itemData”:{“id”:40,”type”:”chapter”,”title”:”Frontmatter”,”container-title”:”Solar Engineering of Thermal Processes”,”publisher”:”John Wiley ; Sons, Inc.”,”page”:”i-xxvi”,”source”:”Wiley Online Library”,”abstract”:”The prelims comprise:

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The angle between the axis of the collector and the line connecting the focus of one of the parabolas with the opposite edge of the aperture is called acceptance half-angle (?c). The relationship between the size of the aperture (2a), the size of the receiver (2a’) and the acceptance half-angle is expressed through the following equation ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”ah5iuh3obg”,”properties”:{“formattedCitation”:”19″,”plainCitation”:”19″,”noteIndex”:0},”citationItems”:{“id”:40,”uris”:”http://zotero.org/users/4612010/items/YA2XS89Z”,”uri”:”http://zotero.org/users/4612010/items/YA2XS89Z”,”itemData”:{“id”:40,”type”:”chapter”,”title”:”Solar Engineering of Thermal Processes”,”container-title”:”Solar Engineering of Thermal Processes”,”publisher”:”John Wiley ; Sons, Inc.”,”page”:”i-xxvi”,”source”:”Wiley Online Library”,”abstract”:”The prelims comprise:

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Introduction”,”URL”:”http://onlinelibrary.wiley.com/doi/10.1002/9781118671603.fmatter/summary”,”ISBN”:”978-1-118-67160-3″,”note”:”DOI: 10.1002/9781118671603.fmatter”,”language”:”en”,”author”:{“family”:”Duffie”,”given”:”John A.”},{“family”:”Beckman”,”given”:”William A.”},”issued”:{“date-parts”:”2013″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 19:
2a’ = 2a sin?c(eq. 3)
Knowing the concentration ratio, it is possible to obtain the acceptance half-angle ADDIN RW.CITE{{57 Fedkin,M. 2015}}15:
Ci = 2a2a’=1sin?c(eq. 4)
The following equations establish the relation between the focal distance of the side parabola and the acceptance half-angle (?c), receiver size, and height of the CPC (h) ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a2ba7ia22a7″,”properties”:{“formattedCitation”:”19″,”plainCitation”:”19″,”noteIndex”:0},”citationItems”:{“id”:40,”uris”:”http://zotero.org/users/4612010/items/YA2XS89Z”,”uri”:”http://zotero.org/users/4612010/items/YA2XS89Z”,”itemData”:{“id”:40,”type”:”chapter”,”title”:”Solar Engineering of Thermal Processes”,”container-title”:”Solar Engineering of Thermal Processes”,”publisher”:”John Wiley ; Sons, Inc.”,”page”:”i-xxvi”,”source”:”Wiley Online Library”,”abstract”:”The prelims comprise:

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f = a'(1 + sin?c)(eq. 5) Add to Nomenclature!
h = f cos?csin2?c(eq. 6) Add to Nomenclature!
CPC concentrators are made, so that each ray that comes into the aperture with an angle smaller than ?c is reflected onto the receiver at the base. However when the angle of the ray is greater than ?c, the ray will be reflected back to the atmosphere. The figure below shows this effectADDIN RW.CITE{{57 Fedkin,M. 2015}}:
Figure SEQ Figure * ARABIC 15: Reflection of the light rays directed to the CPC concentrator at different angles ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”agbs6q6hbp”,”properties”:{“formattedCitation”:”19″,”plainCitation”:”19″,”noteIndex”:0},”citationItems”:{“id”:40,”uris”:”http://zotero.org/users/4612010/items/YA2XS89Z”,”uri”:”http://zotero.org/users/4612010/items/YA2XS89Z”,”itemData”:{“id”:40,”type”:”chapter”,”title”:”Solar Engineering of Thermal Processes”,”container-title”:”Solar Engineering of Thermal Processes”,”publisher”:”John Wiley ; Sons, Inc.”,”page”:”i-xxvi”,”source”:”Wiley Online Library”,”abstract”:”The prelims comprise:

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Preface to the First Edition

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Introduction”,”URL”:”http://onlinelibrary.wiley.com/doi/10.1002/9781118671603.fmatter/summary”,”ISBN”:”978-1-118-67160-3″,”note”:”DOI: 10.1002/9781118671603.fmatter”,”language”:”en”,”author”:{“family”:”Duffie”,”given”:”John A.”},{“family”:”Beckman”,”given”:”William A.”},”issued”:{“date-parts”:”2013″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 19. ADDIN RW.CITE{{57 Fedkin,M. 2015}}Maximum Reflector Concentration DesignThe Maximum Reflector Concentration (MaReCo) is a patented design that originated from research done at Vatenfall. It is based on an asymmetric truncated CPC-collector with a bi-facial flat receiver that is specially adapted for the asymmetric annual solar radiation profiles of high latitudes. A solar thermal collector with this reflector design will be able to better match the asymmetric heat production profile existent at high latitudes to the nearly constant annual demand profile of a Domestic Hot Water (DHW) consumer and thus, be able to prevent stagnation damage ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”mrC9e2aP”,”properties”:{“formattedCitation”:”31″,”plainCitation”:”31″,”noteIndex”:0},”citationItems”:{“id”:82,”uris”:”http://zotero.org/users/4612010/items/JMWQKYYZ”,”uri”:”http://zotero.org/users/4612010/items/JMWQKYYZ”,”itemData”:{“id”:82,”type”:”article-journal”,”title”:”Evaluation of CPC-collector designs for stand-alone, roof- or wall installation”,”container-title”:”Solar Energy”,”collection-title”:”Polymeric Materials for Solar Energy Applications”,”page”:”638-647″,”volume”:”79″,”issue”:”6″,”source”:”ScienceDirect”,”abstract”:”An asymmetrically truncated non-tracking compound parabolic concentrator type collector design concept has been developed. The collector type has a bi-facial absorber and is optimised for northern latitudes. The concept is based on a general reflector form that is truncated to fit different installation conditions. In this paper collectors for stand-alone, roof and wall mounting are studied. Prototypes of six different collectors have been built and outdoor tested. The evaluation gave high annual energy outputs for a roof mounted collector, 925MJ/m2, and a stand-alone collector with Teflon, 781MJ/m2, at an operating temperature of Top=75°C. A special design for roofs facing east or west was also investigated and gave an annual energy output of 349 (east) and 436 (west) MJ/m2 at Top=75°C. If a high solar fraction over the year is the objective, a load adapted collector with a high output during spring/fall and a low output during summer can be used. Such a collector had an output of 490MJ/m2 at Top=75°C. Finally a concentrating collector for wall mounting was evaluated with an estimated annual output of 194MJ/m2 at Top=75°C. The concentrator design concept can also be used for concentrators for PV-modules.”,”DOI”:”10.1016/j.solener.2005.04.023″,”ISSN”:”0038-092X”,”journalAbbreviation”:”Solar Energy”,”author”:{“family”:”Adsten”,”given”:”M.”},{“family”:”Helgesson”,”given”:”A.”},{“family”:”Karlsson”,”given”:”B.”},”issued”:{“date-parts”:”2005″,12,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 31.

The general design of the MaReCo reflector trough consists of two parabolic reflectors with their individual optical axis tilted 20° and 65° from the horizon, collecting all the incoming irradiation between a solar altitude of 20° and 65° as shown in figure 9 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a2eki3b8hjg”,”properties”:{“formattedCitation”:”32″,”plainCitation”:”32″,”noteIndex”:0},”citationItems”:{“id”:90,”uris”:”http://zotero.org/users/4612010/items/SHY5NNQ2″,”uri”:”http://zotero.org/users/4612010/items/SHY5NNQ2″,”itemData”:{“id”:90,”type”:”thesis”,”title”:”Optical Design and Characterization of Solar Concentrators for Photovoltaics”,”publisher”:”Lund University”,”publisher-place”:”2005″,”event-place”:”2005″,”URL”:”http://www.lth.se/fileadmin/energi_byggnadsdesign/images/Publikationer/Bok_EBD-T-05_6_G5_Johan_N.pdf”,”author”:{“family”:”Nilsson”,”given”:”J.”}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 32 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a20jr1p93nu”,”properties”:{“formattedCitation”:”33″,”plainCitation”:”33″,”noteIndex”:0},”citationItems”:{“id”:93,”uris”:”http://zotero.org/users/4612010/items/5BEHYHEX”,”uri”:”http://zotero.org/users/4612010/items/5BEHYHEX”,”itemData”:{“id”:93,”type”:”book”,”title”:”Micro-structured reflector surfaces for a stationary asymmetric parabolic solar concentrator”,”publisher”:”Solar Energy Materials and Solar Cells”,”volume”:”91″,”number-of-pages”:”525″,”source”:”ResearchGate”,”abstract”:”One of the main problems in using parabolic concentrators with standard photovoltaics (PV) cells is the highly non-uniform illumination of the cells. The non-uniform irradiation causes high resistive losses in the standard cells due to their relatively high series resistance. This results in a considerably lowered efficiency. To solve the problem, we introduce three different structured reflectors that will create a more uniform illumination, and also increase the concentration ratio in certain cases. The structures were evaluated in an existing trough system by Monte Carlo ray tracing, and it was found that structures improve the system performance mainly by homogenizing the light on the cells. The yearly irradiation collected in the evaluation system is slightly lower than for a reference with smooth reflectors, but the more uniform illumination of the cells will generate a net increase of the total system performance compared to a system that was optimized with smooth reflectors. The benefit of the increased concentration ratio is increased flexibility in designing new systems with concentration ratios surpassing the limit of existing trough concentrators.”,”note”:”DOI: 10.1016/j.solmat.2006.11.003″,”author”:{“family”:”Nilsson”,”given”:”Johan”},{“family”:”Leutz”,”given”:”Ralf”},{“family”:”Karlsson”,”given”:”Bjoern”},”issued”:{“date-parts”:”2007″,3,23}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 33.

Figure SEQ Figure * ARABIC 16: Sketch of the basic MaReCo design ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a2oicqpvb1d”,”properties”:{“formattedCitation”:”32″,”plainCitation”:”32″,”noteIndex”:0},”citationItems”:{“id”:90,”uris”:”http://zotero.org/users/4612010/items/SHY5NNQ2″,”uri”:”http://zotero.org/users/4612010/items/SHY5NNQ2″,”itemData”:{“id”:90,”type”:”thesis”,”title”:”Optical Design and Characterization of Solar Concentrators for Photovoltaics”,”publisher”:”Lund University”,”publisher-place”:”2005″,”event-place”:”2005″,”URL”:”http://www.lth.se/fileadmin/energi_byggnadsdesign/images/Publikationer/Bok_EBD-T-05_6_G5_Johan_N.pdf”,”author”:{“family”:”Nilsson”,”given”:”J.”}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 32 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”actmggn23k”,”properties”:{“formattedCitation”:”31″,”plainCitation”:”31″,”noteIndex”:0},”citationItems”:{“id”:82,”uris”:”http://zotero.org/users/4612010/items/JMWQKYYZ”,”uri”:”http://zotero.org/users/4612010/items/JMWQKYYZ”,”itemData”:{“id”:82,”type”:”article-journal”,”title”:”Evaluation of CPC-collector designs for stand-alone, roof- or wall installation”,”container-title”:”Solar Energy”,”collection-title”:”Polymeric Materials for Solar Energy Applications”,”page”:”638-647″,”volume”:”79″,”issue”:”6″,”source”:”ScienceDirect”,”abstract”:”An asymmetrically truncated non-tracking compound parabolic concentrator type collector design concept has been developed. The collector type has a bi-facial absorber and is optimised for northern latitudes. The concept is based on a general reflector form that is truncated to fit different installation conditions. In this paper collectors for stand-alone, roof and wall mounting are studied. Prototypes of six different collectors have been built and outdoor tested. The evaluation gave high annual energy outputs for a roof mounted collector, 925MJ/m2, and a stand-alone collector with Teflon, 781MJ/m2, at an operating temperature of Top=75°C. A special design for roofs facing east or west was also investigated and gave an annual energy output of 349 (east) and 436 (west) MJ/m2 at Top=75°C. If a high solar fraction over the year is the objective, a load adapted collector with a high output during spring/fall and a low output during summer can be used. Such a collector had an output of 490MJ/m2 at Top=75°C. Finally a concentrating collector for wall mounting was evaluated with an estimated annual output of 194MJ/m2 at Top=75°C. The concentrator design concept can also be used for concentrators for PV-modules.”,”DOI”:”10.1016/j.solener.2005.04.023″,”ISSN”:”0038-092X”,”journalAbbreviation”:”Solar Energy”,”author”:{“family”:”Adsten”,”given”:”M.”},{“family”:”Helgesson”,”given”:”A.”},{“family”:”Karlsson”,”given”:”B.”},”issued”:{“date-parts”:”2005″,12,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 31
The optical axis from the parabola defines the lower and upper acceptance angles. The reflector is divided in sections A, B and C. Section A comprises a lower side parabola that goes from point 1 to 4. The optical axis is placed along the upper acceptance angle and its focal point on point 5, the upper part of the receiver. Section B is characterized by the circular section between points 1 and 2. Solar radiation that reaches this reflector is directed towards the backside of the reflector which in this case is between point 1 and 5 in this case. However, the receiver could be located anywhere in section B, for example a receiver between points 2 and 5 (the dotted line) would also be possible and have the same theoretical performance. Section C is an upper parabolic reflector that reaches between points 2 and 3, with an optical axis along the lower acceptance angle and focus at point 5.

The dotted line that goes between points 3 and 4 defines a truncation point for both parabolas. However, several other truncations points are possible with an considerable impact on the annual performance of the solar collector.

Additional MaReCo design configurations were created for different situations such as stand-alone, the roof integrated and the wall ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”FMB1l5cr”,”properties”:{“formattedCitation”:”29″,”plainCitation”:”29″,”noteIndex”:0},”citationItems”:{“id”:71,”uris”:”http://zotero.org/users/4612010/items/XQPWU6FF”,”uri”:”http://zotero.org/users/4612010/items/XQPWU6FF”,”itemData”:{“id”:71,”type”:”book”,”title”:”Solar Thermal Collectors at High Latitudes Design and Performance of Non-Tracking Concentrators”,”publisher”:”Uppsala University”,”volume”:”PhD Thesis”,”source”:”ResearchGate”,”abstract”:”ABSTRACT Adsten, M. 2002. Solar thermal collectors at high latitudes -Design and performance of non- tracking concentrators. Acta Universitatis Upsaliensis. Comprehensive,Summaries of Uppsala Dissertations from the Facultyof Science and Technology 697. 78 pp. Uppsala. ISBN 91-554- 5274-4 Solar thermal collectors at high latitudes have been studied, with emphasis on concentrating collectors. A novel design of concentrating collector, the Maximum Reflector Collector (MaReCo), especially designed for high latitudes, has been investigated optically and thermally. The MaReCo is an asymmetrical,compound,parabolic concentrator with a bi-facial absorber. The collector can be adapted to various installation conditions, for example stand- alone, roof- or wall mounted. MaReCo prototypes have been built and outdoor-tested. The evaluation showed ,that all types work ,as expected ,and that the highest annually delivered energy output, 340 kWh/m,, is found for the roof MaReCo. A study of the heat-losses from the stand-alone MaReCo lead to the conclusion that ,teflon transparent insulation should be placed around the absorber, which decreases the U-value by about 30%. A method was developed to theoreticallystudy the projected radiation distribution incident onthe,MaReCo bi-facial absorber. The study showed ,that the geometry ,of the ,collectors could be improved ,by slight ,changes in the ,acceptance intervals. It also indicated that the MaReCo design concept could be used ,also at mid-European ,latitudes if the geometry ,is changed. Anovel,method ,was ,used to perform ,outdoor measurements ,of the ,distribution of concentrated light on the ,absorber and then to calculate ,the annually collected ,zero-loss energy, Ea,corr, together with the annual optical efficiency factor. A study using this method indicated that the absorber should be mounted,along the 20° optical axis instead of along,the”,”author”:{“family”:”Adsten”,”given”:”Monika”},”issued”:{“date-parts”:”2002″,1,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 29. These configurations are described below in more detail.

The stand-alone MaReCoThe figure on the right shows the stand-alone MaReCo design. This design has a concentration factor (Ci) of 2.2, an upper acceptance angle of 65°, a lower acceptance angle of 20° and an aperture tilt of 30° ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”1WzDF6XT”,”properties”:{“formattedCitation”:”29″,”plainCitation”:”29″,”noteIndex”:0},”citationItems”:{“id”:71,”uris”:”http://zotero.org/users/4612010/items/XQPWU6FF”,”uri”:”http://zotero.org/users/4612010/items/XQPWU6FF”,”itemData”:{“id”:71,”type”:”book”,”title”:”Solar Thermal Collectors at High Latitudes Design and Performance of Non-Tracking Concentrators”,”publisher”:”Uppsala University”,”volume”:”PhD Thesis”,”source”:”ResearchGate”,”abstract”:”ABSTRACT Adsten, M. 2002. Solar thermal collectors at high latitudes -Design and performance of non- tracking concentrators. Acta Universitatis Upsaliensis. Comprehensive,Summaries of Uppsala Dissertations from the Facultyof Science and Technology 697. 78 pp. Uppsala. ISBN 91-554- 5274-4 Solar thermal collectors at high latitudes have been studied, with emphasis on concentrating collectors. A novel design of concentrating collector, the Maximum Reflector Collector (MaReCo), especially designed for high latitudes, has been investigated optically and thermally. The MaReCo is an asymmetrical,compound,parabolic concentrator with a bi-facial absorber. The collector can be adapted to various installation conditions, for example stand- alone, roof- or wall mounted. MaReCo prototypes have been built and outdoor-tested. The evaluation showed ,that all types work ,as expected ,and that the highest annually delivered energy output, 340 kWh/m,, is found for the roof MaReCo. A study of the heat-losses from the stand-alone MaReCo lead to the conclusion that ,teflon transparent insulation should be placed around the absorber, which decreases the U-value by about 30%. A method was developed to theoreticallystudy the projected radiation distribution incident onthe,MaReCo bi-facial absorber. The study showed ,that the geometry ,of the ,collectors could be improved ,by slight ,changes in the ,acceptance intervals. It also indicated that the MaReCo design concept could be used ,also at mid-European ,latitudes if the geometry ,is changed. Anovel,method ,was ,used to perform ,outdoor measurements ,of the ,distribution of concentrated light on the ,absorber and then to calculate ,the annually collected ,zero-loss energy, Ea,corr, together with the annual optical efficiency factor. A study using this method indicated that the absorber should be mounted,along the 20° optical axis instead of along,the”,”author”:{“family”:”Adsten”,”given”:”Monika”},”issued”:{“date-parts”:”2002″,1,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 29.

Figure SEQ Figure * ARABIC 17: Section of the stand-alone MaReCo for Stockholm conditions, a stationary asymmetrically truncated wedge CPC with acceptance angles between 20° and 65°. Aperture tilt 30° ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a237ckf45m5″,”properties”:{“formattedCitation”:”31″,”plainCitation”:”31″,”noteIndex”:0},”citationItems”:{“id”:82,”uris”:”http://zotero.org/users/4612010/items/JMWQKYYZ”,”uri”:”http://zotero.org/users/4612010/items/JMWQKYYZ”,”itemData”:{“id”:82,”type”:”article-journal”,”title”:”Evaluation of CPC-collector designs for stand-alone, roof- or wall installation”,”container-title”:”Solar Energy”,”collection-title”:”Polymeric Materials for Solar Energy Applications”,”page”:”638-647″,”volume”:”79″,”issue”:”6″,”source”:”ScienceDirect”,”abstract”:”An asymmetrically truncated non-tracking compound parabolic concentrator type collector design concept has been developed. The collector type has a bi-facial absorber and is optimised for northern latitudes. The concept is based on a general reflector form that is truncated to fit different installation conditions. In this paper collectors for stand-alone, roof and wall mounting are studied. Prototypes of six different collectors have been built and outdoor tested. The evaluation gave high annual energy outputs for a roof mounted collector, 925MJ/m2, and a stand-alone collector with Teflon, 781MJ/m2, at an operating temperature of Top=75°C. A special design for roofs facing east or west was also investigated and gave an annual energy output of 349 (east) and 436 (west) MJ/m2 at Top=75°C. If a high solar fraction over the year is the objective, a load adapted collector with a high output during spring/fall and a low output during summer can be used. Such a collector had an output of 490MJ/m2 at Top=75°C. Finally a concentrating collector for wall mounting was evaluated with an estimated annual output of 194MJ/m2 at Top=75°C. The concentrator design concept can also be used for concentrators for PV-modules.”,”DOI”:”10.1016/j.solener.2005.04.023″,”ISSN”:”0038-092X”,”journalAbbreviation”:”Solar Energy”,”author”:{“family”:”Adsten”,”given”:”M.”},{“family”:”Helgesson”,”given”:”A.”},{“family”:”Karlsson”,”given”:”B.”},”issued”:{“date-parts”:”2005″,12,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 31 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a1vtqoaoion”,”properties”:{“formattedCitation”:”32″,”plainCitation”:”32″,”noteIndex”:0},”citationItems”:{“id”:90,”uris”:”http://zotero.org/users/4612010/items/SHY5NNQ2″,”uri”:”http://zotero.org/users/4612010/items/SHY5NNQ2″,”itemData”:{“id”:90,”type”:”thesis”,”title”:”Optical Design and Characterization of Solar Concentrators for Photovoltaics”,”publisher”:”Lund University”,”publisher-place”:”2005″,”event-place”:”2005″,”URL”:”http://www.lth.se/fileadmin/energi_byggnadsdesign/images/Publikationer/Bok_EBD-T-05_6_G5_Johan_N.pdf”,”author”:{“family”:”Nilsson”,”given”:”J.”}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 32.The roof integrated MaReCoThe roof integrated MaReCo designed features a cover glass start that starts immediately where the circular section of the MaReCo ends, as shown by the following figure. This MaReCo design has a concentration factor (Ci) of 1.5 and is meant for a roof with a tilt of 30° ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”VHv5VAc5″,”properties”:{“formattedCitation”:”29″,”plainCitation”:”29″,”noteIndex”:0},”citationItems”:{“id”:71,”uris”:”http://zotero.org/users/4612010/items/XQPWU6FF”,”uri”:”http://zotero.org/users/4612010/items/XQPWU6FF”,”itemData”:{“id”:71,”type”:”book”,”title”:”Solar Thermal Collectors at High Latitudes Design and Performance of Non-Tracking Concentrators”,”publisher”:”Uppsala University”,”volume”:”PhD Thesis”,”source”:”ResearchGate”,”abstract”:”ABSTRACT Adsten, M. 2002. Solar thermal collectors at high latitudes -Design and performance of non- tracking concentrators. Acta Universitatis Upsaliensis. Comprehensive,Summaries of Uppsala Dissertations from the Facultyof Science and Technology 697. 78 pp. Uppsala. ISBN 91-554- 5274-4 Solar thermal collectors at high latitudes have been studied, with emphasis on concentrating collectors. A novel design of concentrating collector, the Maximum Reflector Collector (MaReCo), especially designed for high latitudes, has been investigated optically and thermally. The MaReCo is an asymmetrical,compound,parabolic concentrator with a bi-facial absorber. The collector can be adapted to various installation conditions, for example stand- alone, roof- or wall mounted. MaReCo prototypes have been built and outdoor-tested. The evaluation showed ,that all types work ,as expected ,and that the highest annually delivered energy output, 340 kWh/m,, is found for the roof MaReCo. A study of the heat-losses from the stand-alone MaReCo lead to the conclusion that ,teflon transparent insulation should be placed around the absorber, which decreases the U-value by about 30%. A method was developed to theoreticallystudy the projected radiation distribution incident onthe,MaReCo bi-facial absorber. The study showed ,that the geometry ,of the ,collectors could be improved ,by slight ,changes in the ,acceptance intervals. It also indicated that the MaReCo design concept could be used ,also at mid-European ,latitudes if the geometry ,is changed. Anovel,method ,was ,used to perform ,outdoor measurements ,of the ,distribution of concentrated light on the ,absorber and then to calculate ,the annually collected ,zero-loss energy, Ea,corr, together with the annual optical efficiency factor. A study using this method indicated that the absorber should be mounted,along the 20° optical axis instead of along,the”,”author”:{“family”:”Adsten”,”given”:”Monika”},”issued”:{“date-parts”:”2002″,1,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 29. All the radiation normal to the cover glass is accepted.

Figure SEQ Figure * ARABIC 18: Section of the roof integrated MaReCo design for a tilt of 30o and optical axis 90° from the cover glass ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a2d40vda59h”,”properties”:{“formattedCitation”:”31″,”plainCitation”:”31″,”noteIndex”:0},”citationItems”:{“id”:82,”uris”:”http://zotero.org/users/4612010/items/JMWQKYYZ”,”uri”:”http://zotero.org/users/4612010/items/JMWQKYYZ”,”itemData”:{“id”:82,”type”:”article-journal”,”title”:”Evaluation of CPC-collector designs for stand-alone, roof- or wall installation”,”container-title”:”Solar Energy”,”collection-title”:”Polymeric Materials for Solar Energy Applications”,”page”:”638-647″,”volume”:”79″,”issue”:”6″,”source”:”ScienceDirect”,”abstract”:”An asymmetrically truncated non-tracking compound parabolic concentrator type collector design concept has been developed. The collector type has a bi-facial absorber and is optimised for northern latitudes. 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The concentrator design concept can also be used for concentrators for PV-modules.”,”DOI”:”10.1016/j.solener.2005.04.023″,”ISSN”:”0038-092X”,”journalAbbreviation”:”Solar Energy”,”author”:{“family”:”Adsten”,”given”:”M.”},{“family”:”Helgesson”,”given”:”A.”},{“family”:”Karlsson”,”given”:”B.”},”issued”:{“date-parts”:”2005″,12,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 31Other roof integrated MaReCo designs were developed, such as the roof MaReCo for east/west and the spring/fall MaReCo. The roof MaReCo for east/west is shown below. It has a Ci = 2.0 and was designed for roof facing west. It accepts radiation between 20° and 90°, meaning that the optical axis is 70° from the cover glass ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”whCCkDDB”,”properties”:{“formattedCitation”:”29″,”plainCitation”:”29″,”noteIndex”:0},”citationItems”:{“id”:71,”uris”:”http://zotero.org/users/4612010/items/XQPWU6FF”,”uri”:”http://zotero.org/users/4612010/items/XQPWU6FF”,”itemData”:{“id”:71,”type”:”book”,”title”:”Solar Thermal Collectors at High Latitudes Design and Performance of Non-Tracking Concentrators”,”publisher”:”Uppsala University”,”volume”:”PhD Thesis”,”source”:”ResearchGate”,”abstract”:”ABSTRACT Adsten, M. 2002. Solar thermal collectors at high latitudes -Design and performance of non- tracking concentrators. Acta Universitatis Upsaliensis. Comprehensive,Summaries of Uppsala Dissertations from the Facultyof Science and Technology 697. 78 pp. Uppsala. ISBN 91-554- 5274-4 Solar thermal collectors at high latitudes have been studied, with emphasis on concentrating collectors. A novel design of concentrating collector, the Maximum Reflector Collector (MaReCo), especially designed for high latitudes, has been investigated optically and thermally. The MaReCo is an asymmetrical,compound,parabolic concentrator with a bi-facial absorber. The collector can be adapted to various installation conditions, for example stand- alone, roof- or wall mounted. MaReCo prototypes have been built and outdoor-tested. The evaluation showed ,that all types work ,as expected ,and that the highest annually delivered energy output, 340 kWh/m,, is found for the roof MaReCo. A study of the heat-losses from the stand-alone MaReCo lead to the conclusion that ,teflon transparent insulation should be placed around the absorber, which decreases the U-value by about 30%. A method was developed to theoreticallystudy the projected radiation distribution incident onthe,MaReCo bi-facial absorber. The study showed ,that the geometry ,of the ,collectors could be improved ,by slight ,changes in the ,acceptance intervals. It also indicated that the MaReCo design concept could be used ,also at mid-European ,latitudes if the geometry ,is changed. Anovel,method ,was ,used to perform ,outdoor measurements ,of the ,distribution of concentrated light on the ,absorber and then to calculate ,the annually collected ,zero-loss energy, Ea,corr, together with the annual optical efficiency factor. A study using this method indicated that the absorber should be mounted,along the 20° optical axis instead of along,the”,”author”:{“family”:”Adsten”,”given”:”Monika”},”issued”:{“date-parts”:”2002″,1,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 29.

Figure SEQ Figure * ARABIC 19: Section of the east/west roof MaReCo 26The roof spring/fall MaReCo has been designed for a roof tilted 30° and it has an optical axis at 45° from the horizon. Direct radiation that hits the reflector at an angle smaller than 15° from the aperture normal will be reflected out of the collector which prevents overheating. This design has a concentration factor (Ci) of 1.8 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”oKEq4n50″,”properties”:{“formattedCitation”:”29″,”plainCitation”:”29″,”noteIndex”:0},”citationItems”:{“id”:71,”uris”:”http://zotero.org/users/4612010/items/XQPWU6FF”,”uri”:”http://zotero.org/users/4612010/items/XQPWU6FF”,”itemData”:{“id”:71,”type”:”book”,”title”:”Solar Thermal Collectors at High Latitudes Design and Performance of Non-Tracking Concentrators”,”publisher”:”Uppsala University”,”volume”:”PhD Thesis”,”source”:”ResearchGate”,”abstract”:”ABSTRACT Adsten, M. 2002. Solar thermal collectors at high latitudes -Design and performance of non- tracking concentrators. Acta Universitatis Upsaliensis. Comprehensive,Summaries of Uppsala Dissertations from the Facultyof Science and Technology 697. 78 pp. Uppsala. ISBN 91-554- 5274-4 Solar thermal collectors at high latitudes have been studied, with emphasis on concentrating collectors. A novel design of concentrating collector, the Maximum Reflector Collector (MaReCo), especially designed for high latitudes, has been investigated optically and thermally. The MaReCo is an asymmetrical,compound,parabolic concentrator with a bi-facial absorber. The collector can be adapted to various installation conditions, for example stand- alone, roof- or wall mounted. MaReCo prototypes have been built and outdoor-tested. The evaluation showed ,that all types work ,as expected ,and that the highest annually delivered energy output, 340 kWh/m,, is found for the roof MaReCo. A study of the heat-losses from the stand-alone MaReCo lead to the conclusion that ,teflon transparent insulation should be placed around the absorber, which decreases the U-value by about 30%. A method was developed to theoreticallystudy the projected radiation distribution incident onthe,MaReCo bi-facial absorber. The study showed ,that the geometry ,of the ,collectors could be improved ,by slight ,changes in the ,acceptance intervals. It also indicated that the MaReCo design concept could be used ,also at mid-European ,latitudes if the geometry ,is changed. Anovel,method ,was ,used to perform ,outdoor measurements ,of the ,distribution of concentrated light on the ,absorber and then to calculate ,the annually collected ,zero-loss energy, Ea,corr, together with the annual optical efficiency factor. A study using this method indicated that the absorber should be mounted,along the 20° optical axis instead of along,the”,”author”:{“family”:”Adsten”,”given”:”Monika”},”issued”:{“date-parts”:”2002″,1,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 29.

Figure 20: Section of the spring/fall MaReCo 26.The wall MaReCoThis design was developed for a south facing wall, in order to be an alternative to standard installations. The figure below shows the design which has a Ci = 2.2, an optical axis at 25° from the horizon and an acceptance angle between 25° and 90° from the horizon ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”YSRdtX8n”,”properties”:{“formattedCitation”:”29″,”plainCitation”:”29″,”noteIndex”:0},”citationItems”:{“id”:71,”uris”:”http://zotero.org/users/4612010/items/XQPWU6FF”,”uri”:”http://zotero.org/users/4612010/items/XQPWU6FF”,”itemData”:{“id”:71,”type”:”book”,”title”:”Solar Thermal Collectors at High Latitudes Design and Performance of Non-Tracking Concentrators”,”publisher”:”Uppsala University”,”volume”:”PhD Thesis”,”source”:”ResearchGate”,”abstract”:”ABSTRACT Adsten, M. 2002. Solar thermal collectors at high latitudes -Design and performance of non- tracking concentrators. Acta Universitatis Upsaliensis. Comprehensive,Summaries of Uppsala Dissertations from the Facultyof Science and Technology 697. 78 pp. Uppsala. ISBN 91-554- 5274-4 Solar thermal collectors at high latitudes have been studied, with emphasis on concentrating collectors. A novel design of concentrating collector, the Maximum Reflector Collector (MaReCo), especially designed for high latitudes, has been investigated optically and thermally. The MaReCo is an asymmetrical,compound,parabolic concentrator with a bi-facial absorber. The collector can be adapted to various installation conditions, for example stand- alone, roof- or wall mounted. MaReCo prototypes have been built and outdoor-tested. The evaluation showed ,that all types work ,as expected ,and that the highest annually delivered energy output, 340 kWh/m,, is found for the roof MaReCo. A study of the heat-losses from the stand-alone MaReCo lead to the conclusion that ,teflon transparent insulation should be placed around the absorber, which decreases the U-value by about 30%. A method was developed to theoreticallystudy the projected radiation distribution incident onthe,MaReCo bi-facial absorber. The study showed ,that the geometry ,of the ,collectors could be improved ,by slight ,changes in the ,acceptance intervals. It also indicated that the MaReCo design concept could be used ,also at mid-European ,latitudes if the geometry ,is changed. Anovel,method ,was ,used to perform ,outdoor measurements ,of the ,distribution of concentrated light on the ,absorber and then to calculate ,the annually collected ,zero-loss energy, Ea,corr, together with the annual optical efficiency factor. A study using this method indicated that the absorber should be mounted,along the 20° optical axis instead of along,the”,”author”:{“family”:”Adsten”,”given”:”Monika”},”issued”:{“date-parts”:”2002″,1,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 29.

Figure SEQ Figure * ARABIC 21: Section of the wall MaReCo 26.PVT collectors: Advantages and DisadvantagesAs mentioned in the author´s papers IV and I, photovoltaic/thermal (PVT) collectors produce both heat and electricity. The main benefits of PVT collectors when compared to standard thermal and photovoltaic (PV) solar collectors are:
• The possibility of increasing cell efficiency by reducing the cell operational temperature when the hot water is extracted at low temperatures. In order for this to be achieved, it is fundamental that the panel design is able to transfer the heat from the cells to the cooling liquid efficiently as well as homogeneously.

• The production of one unit of PVT uses fewer raw materials than an equivalent area of thermal and photovoltaic panels. This is expected to enable a lower production cost per kWh of annual produced combined power.

• Reduction of the installation area, which enables the deployment of more installed capacity per roof area and should also lower the installation costs.

The main disadvantages for PVT´s are the higher complexity in both for collector production and installation and the reduced market share since it requires customers that need both the heat and the electricity.

Table SEQ Table * ARABIC 1: Advantages and disadvantages of PVT collectors (Vs T and PV)Topic Advantage Disadvantage
Efficiency Higher energy output/m2 compared to PV and T. Possibility to increase electrical efficiency by cooling. Heat has more value at high temperatures but this reduces electrical output.

Collector Cost Fewer raw materials needed to obtain the same energy output Early in the Technology curve. Cell Price has greatly decreased making PVT (and T) less attractive.

Production Cost – Increased complexity at production level
Installation Cost/ Reliability Lower installation cost can be achieved due to smaller area for the same output Increased complexity at installation level
Market – Nice Market (require need for heat and electricity)
C-PVT collector: Advantages and DisadvantagesAs mentioned in the author´s papers IV and I, some PVT manufacturers combine the concept with concentration to reduce the usage of PV cells and thermal absorber material. Concentration carries the penalty due to extra reflection losses from the reflector and a lower Incident Angle Modifier (IAM) profile but at the same time, it reduces the amount of expensive components (solar cells, receiver and/or selective surface) ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a1ip85cqb8n”,”properties”:{“formattedCitation”:”23″,”plainCitation”:”23″,”noteIndex”:0},”citationItems”:{“id”:53,”uris”:”http://zotero.org/users/4612010/items/ZGITLAZL”,”uri”:”http://zotero.org/users/4612010/items/ZGITLAZL”,”itemData”:{“id”:53,”type”:”article-journal”,”title”:”Concentrated photovoltaic thermal (CPVT) solar collector systems: Part I – Fundamentals, design considerations and current technologies”,”container-title”:”Renewable and Sustainable Energy Reviews”,”page”:”1500-1565″,”volume”:”50″,”issue”:”Supplement C”,”source”:”ScienceDirect”,”abstract”:”Concentrated photovoltaic thermal (CPVT) solar collectors have been gaining ever-increasing attention from the scientific community and industrial developers due to their promising potential to pave the way for the penetration of solar energy into modern day power generation technologies. CPVTs? flexibility, manufacturability, high efficiency, and multi-output nature inspired many innovative designs and design improvements available in the literature. In this study, a comprehensive, up-to-date review of the governing scientific basics, system variations, and technological advances in CPVT systems will be presented. The study is split into two parts. The first part covers CPVTs? characteristics and design considerations in addition to a review of the principals and technological advances in the solar components that compose a CPVT (i.e., photovoltaic cells, solar thermal collectors, concentrator optics, tracking mechanisms, concentrated photovoltaics, and concentrated solar thermal systems). While the second part thoroughly covers CPVTs? published studies, application areas, performance assessment, commercial initiatives, and research prospects.”,”DOI”:”10.1016/j.rser.2015.05.036″,”ISSN”:”1364-0321″,”shortTitle”:”Concentrated photovoltaic thermal (CPVT) solar collector systems”,”journalAbbreviation”:”Renewable and Sustainable Energy Reviews”,”author”:{“family”:”Sharaf”,”given”:”Omar Z.”},{“family”:”Orhan”,”given”:”Mehmet F.”},”issued”:{“date-parts”:”2015″,10,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 23. In the end, it is a trade between the positive effect of lowering the collector cost and the negative effect of lower output per square meter. The steep decrease in the price of silicone solar cell made C-PV concepts less popular. However, in PVT collectors, the receiver becomes again more expensive since it features both the thermal absorber and the PV cells.

Concentration also helps to reduce the heat losses, though conduction and convection losses. This way, concentration also allows achieving higher temperatures, although higher temperatures will reduce the efficiency of the solar cells in PVT collectors ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a2k6sopet3t”,”properties”:{“formattedCitation”:”23″,”plainCitation”:”23″,”noteIndex”:0},”citationItems”:{“id”:53,”uris”:”http://zotero.org/users/4612010/items/ZGITLAZL”,”uri”:”http://zotero.org/users/4612010/items/ZGITLAZL”,”itemData”:{“id”:53,”type”:”article-journal”,”title”:”Concentrated photovoltaic thermal (CPVT) solar collector systems: Part I – Fundamentals, design considerations and current technologies”,”container-title”:”Renewable and Sustainable Energy Reviews”,”page”:”1500-1565″,”volume”:”50″,”issue”:”Supplement C”,”source”:”ScienceDirect”,”abstract”:”Concentrated photovoltaic thermal (CPVT) solar collectors have been gaining ever-increasing attention from the scientific community and industrial developers due to their promising potential to pave the way for the penetration of solar energy into modern day power generation technologies. CPVTs? flexibility, manufacturability, high efficiency, and multi-output nature inspired many innovative designs and design improvements available in the literature. In this study, a comprehensive, up-to-date review of the governing scientific basics, system variations, and technological advances in CPVT systems will be presented. The study is split into two parts. The first part covers CPVTs? characteristics and design considerations in addition to a review of the principals and technological advances in the solar components that compose a CPVT (i.e., photovoltaic cells, solar thermal collectors, concentrator optics, tracking mechanisms, concentrated photovoltaics, and concentrated solar thermal systems). While the second part thoroughly covers CPVTs? published studies, application areas, performance assessment, commercial initiatives, and research prospects.”,”DOI”:”10.1016/j.rser.2015.05.036″,”ISSN”:”1364-0321″,”shortTitle”:”Concentrated photovoltaic thermal (CPVT) solar collector systems”,”journalAbbreviation”:”Renewable and Sustainable Energy Reviews”,”author”:{“family”:”Sharaf”,”given”:”Omar Z.”},{“family”:”Orhan”,”given”:”Mehmet F.”},”issued”:{“date-parts”:”2015″,10,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 23 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a2nr21gs670″,”properties”:{“formattedCitation”:”22″,”plainCitation”:”22″,”dontUpdate”:true,”noteIndex”:0},”citationItems”:{“id”:53,”uris”:”http://zotero.org/users/4612010/items/ZGITLAZL”,”uri”:”http://zotero.org/users/4612010/items/ZGITLAZL”,”itemData”:{“id”:53,”type”:”article-journal”,”title”:”Concentrated photovoltaic thermal (CPVT) solar collector systems: Part I – Fundamentals, design considerations and current technologies”,”container-title”:”Renewable and Sustainable Energy Reviews”,”page”:”1500-1565″,”volume”:”50″,”issue”:”Supplement C”,”source”:”ScienceDirect”,”abstract”:”Concentrated photovoltaic thermal (CPVT) solar collectors have been gaining ever-increasing attention from the scientific community and industrial developers due to their promising potential to pave the way for the penetration of solar energy into modern day power generation technologies. CPVTs? flexibility, manufacturability, high efficiency, and multi-output nature inspired many innovative designs and design improvements available in the literature. In this study, a comprehensive, up-to-date review of the governing scientific basics, system variations, and technological advances in CPVT systems will be presented. The study is split into two parts. The first part covers CPVTs? characteristics and design considerations in addition to a review of the principals and technological advances in the solar components that compose a CPVT (i.e., photovoltaic cells, solar thermal collectors, concentrator optics, tracking mechanisms, concentrated photovoltaics, and concentrated solar thermal systems). While the second part thoroughly covers CPVTs? published studies, application areas, performance assessment, commercial initiatives, and research prospects.”,”DOI”:”10.1016/j.rser.2015.05.036″,”ISSN”:”1364-0321″,”shortTitle”:”Concentrated photovoltaic thermal (CPVT) solar collector systems”,”journalAbbreviation”:”Renewable and Sustainable Energy Reviews”,”author”:{“family”:”Sharaf”,”given”:”Omar Z.”},{“family”:”Orhan”,”given”:”Mehmet F.”},”issued”:{“date-parts”:”2015″,10,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} .

Some of the disadvantages concentration are Aesthetics (bulkier), higher stagnation temperatures which lead to more expensive components and lower power density ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a6e5bghtdt”,”properties”:{“formattedCitation”:”23″,”plainCitation”:”23″,”noteIndex”:0},”citationItems”:{“id”:53,”uris”:”http://zotero.org/users/4612010/items/ZGITLAZL”,”uri”:”http://zotero.org/users/4612010/items/ZGITLAZL”,”itemData”:{“id”:53,”type”:”article-journal”,”title”:”Concentrated photovoltaic thermal (CPVT) solar collector systems: Part I – Fundamentals, design considerations and current technologies”,”container-title”:”Renewable and Sustainable Energy Reviews”,”page”:”1500-1565″,”volume”:”50″,”issue”:”Supplement C”,”source”:”ScienceDirect”,”abstract”:”Concentrated photovoltaic thermal (CPVT) solar collectors have been gaining ever-increasing attention from the scientific community and industrial developers due to their promising potential to pave the way for the penetration of solar energy into modern day power generation technologies. CPVTs? flexibility, manufacturability, high efficiency, and multi-output nature inspired many innovative designs and design improvements available in the literature. In this study, a comprehensive, up-to-date review of the governing scientific basics, system variations, and technological advances in CPVT systems will be presented. The study is split into two parts. The first part covers CPVTs? characteristics and design considerations in addition to a review of the principals and technological advances in the solar components that compose a CPVT (i.e., photovoltaic cells, solar thermal collectors, concentrator optics, tracking mechanisms, concentrated photovoltaics, and concentrated solar thermal systems). While the second part thoroughly covers CPVTs? published studies, application areas, performance assessment, commercial initiatives, and research prospects.”,”DOI”:”10.1016/j.rser.2015.05.036″,”ISSN”:”1364-0321″,”shortTitle”:”Concentrated photovoltaic thermal (CPVT) solar collector systems”,”journalAbbreviation”:”Renewable and Sustainable Energy Reviews”,”author”:{“family”:”Sharaf”,”given”:”Omar Z.”},{“family”:”Orhan”,”given”:”Mehmet F.”},”issued”:{“date-parts”:”2015″,10,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 23.

A number of factors are important such as simplicity or aesthetic are important for solar costumers, however, in the end, the most important number in solar remains the cost per kWh of heat and electricity produced, including the installation cost ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a2q25cs3vd7″,”properties”:{“formattedCitation”:”34″,”plainCitation”:”34″,”noteIndex”:0},”citationItems”:{“id”:136,”uris”:”http://zotero.org/users/4612010/items/T8T9MY2I”,”uri”:”http://zotero.org/users/4612010/items/T8T9MY2I”,”itemData”:{“id”:136,”type”:”article-journal”,”title”:”Concentrated photovoltaic thermal (CPVT) solar collector systems: Part II – Implemented systems, performance assessment, and future directions”,”container-title”:”Renewable and Sustainable Energy Reviews”,”page”:”1566-1633″,”volume”:”50″,”source”:”ScienceDirect”,”abstract”:”Concentrated photovoltaic thermal (CPVT) solar collectors have been gaining ever-increasing attention from the scientific community and industrial developers due to their promising potential to pave the way for the penetration of solar energy into modern day power generation technologies. CPVTs? flexibility, manufacturability, high efficiency, and multi-output nature inspired many innovative designs and design improvements available in the literature. In this study, a comprehensive, up-to-date review of the governing scientific basics, system variations, and technological advances in CPVT systems will be presented. The study is split into two parts. The first part covers CPVTs’ characteristics and design considerations in addition to an overview of the principals and technological advances in the solar components that compose a CPVT (i.e., solar photovoltaics, solar thermal collectors, solar concentrator optics, and concentrated solar technologies). While the second part thoroughly covers CPVTs? published studies, application areas, performance assessment, commercial initiatives, and research prospects.”,”DOI”:”10.1016/j.rser.2014.07.215″,”ISSN”:”1364-0321″,”shortTitle”:”Concentrated photovoltaic thermal (CPVT) solar collector systems”,”journalAbbreviation”:”Renewable and Sustainable Energy Reviews”,”author”:{“family”:”Sharaf”,”given”:”Omar Z.”},{“family”:”Orhan”,”given”:”Mehmet F.”},”issued”:{“date-parts”:”2015″,10,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 34. This way, the table below shows a list of the factors but does not quantify their importance.

Table SEQ Table * ARABIC 2: Advantages and disadvantages of C-PVT collectors (Vs PVT)Topic Advantage Disadvantage
Electrical Output/Cost Concentration reduces costs Concentration also reduces output/m2
Thermal Output/Cost Concentration reduces heat losses and increases range of possible working temperatures Higher stagnation temperatures
Product complexity – Concentration increases complexity
Aesthetics – Concentration can reduce aesthetics
The impact of shading and concentration in PV panels and solar thermal collectorsShading can be caused by many factors, such as building, trees or other solar panels. As mentioned in the author´s papers IV and I, shading has a considerably different impact on PV panels than on thermal collectors. In PV modules, the solar cells are commonly connected in series, thus one completely shaded solar cell will reduce the output of the whole string. Bypass diodes can be used to mitigate this effect by allowing current to flow in a different path at the expense of a minor fraction of the total power. However, the introduction of diodes increases both assembly time and material cost which leads to increased costs. On the other hand, diodes also prevent hotspots that can destroy PV panels ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a1gbrku86e4″,”properties”:{“formattedCitation”:”35″,”plainCitation”:”35″,”noteIndex”:0},”citationItems”:{“id”:120,”uris”:”http://zotero.org/users/4612010/items/BP77M2ZF”,”uri”:”http://zotero.org/users/4612010/items/BP77M2ZF”,”itemData”:{“id”:120,”type”:”chapter”,”title”:”Solar Cells Failure Modes and Improvement of Reverse Characteristics”,”container-title”:”Fourth E.C. Photovoltaic Solar Energy Conference”,”publisher”:”Springer, Dordrecht”,”page”:”392-398″,”source”:”link.springer.com”,”abstract”:”The growing number of large photovoltaic installations calls attention to the possible development of “hot spots” leading to a loss of power in the best case. Catastrophic consequences on the whole array can be avoided by particular precautions taken at the cell, panel and system design level. Hot spots problems arise in modules when one or several cells become back biased and operate in the negative voltage quadrant, as a result of short-circuit current mismatch, cell cracking or shadowing.Optimization of system designs with diodes protections has already been demonstrated by France-Photon in a previous paper(l). Further to the industrialised matching of the cells in a same module, an important result of this study is that we can improve the capability of dissipating reverse power by decreasing the shunt resistance with negligible sacrifice of the direct peak power. After a complete study of the dark direct current, we show for our basic technology that the main parameter which governs the slope of the reverse characteristic is the shunt resistance and we indicate trends to understand its fondamental causes and their relative weight for single and semicrystalline cells.”,”URL”:”https://link.springer.com/chapter/10.1007/978-94-009-7898-0_64″,”ISBN”:”978-94-009-7900-0″,”note”:”DOI: 10.1007/978-94-009-7898-0_64″,”language”:”en”,”author”:{“family”:”Ricaud”,”given”:”A. M.”},”issued”:{“date-parts”:”1982″},”accessed”:{“date-parts”:”2018″,1,22}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 35 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a2mgmctf7mh”,”properties”:{“formattedCitation”:”36″,”plainCitation”:”36″,”noteIndex”:0},”citationItems”:{“id”:122,”uris”:”http://zotero.org/users/4612010/items/25JRUURE”,”uri”:”http://zotero.org/users/4612010/items/25JRUURE”,”itemData”:{“id”:122,”type”:”article-journal”,”title”:”Modeling and detection of hotspot in shaded photovoltaic cells”,”container-title”:”IEEE Transactions on Very Large Scale Integration (VLSI) Systems”,”page”:”1031–1039″,”volume”:”23″,”issue”:”6″,”source”:”Google Scholar”,”author”:{“family”:”Rossi”,”given”:”Daniele”},{“family”:”Omaña”,”given”:”Martin”},{“family”:”Giaffreda”,”given”:”Daniele”},{“family”:”Metra”,”given”:”Cecilia”},”issued”:{“date-parts”:”2015″}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 36. In thermal collectors, the decrease in power produced due to shading is approximately proportional to the shaded area. Thus, shading clearly has a much bigger impact on PV panels than thermal collectors I.

Non-uniform concentration is a feature of all compound parabolic concentrators (CPC) ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a2fkkpf3701″,”properties”:{“formattedCitation”:”19″,”plainCitation”:”19″,”noteIndex”:0},”citationItems”:{“id”:40,”uris”:”http://zotero.org/users/4612010/items/YA2XS89Z”,”uri”:”http://zotero.org/users/4612010/items/YA2XS89Z”,”itemData”:{“id”:40,”type”:”chapter”,”title”:”Solar Engineering of Thermal Processes”,”container-title”:”Solar Engineering of Thermal Processes”,”publisher”:”John Wiley & Sons, Inc.”,”page”:”i-xxvi”,”source”:”Wiley Online Library”,”abstract”:”The prelims comprise:

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Copyright

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Contents

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Preface

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Preface to the Third Edition

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Preface to the Second Edition

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Preface to the First Edition

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Introduction”,”URL”:”http://onlinelibrary.wiley.com/doi/10.1002/9781118671603.fmatter/summary”,”ISBN”:”978-1-118-67160-3″,”note”:”DOI: 10.1002/9781118671603.fmatter”,”language”:”en”,”author”:{“family”:”Duffie”,”given”:”John A.”},{“family”:”Beckman”,”given”:”William A.”},”issued”:{“date-parts”:”2013″},”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 19 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a1v153d0f24″,”properties”:{“formattedCitation”:”28″,”plainCitation”:”28″,”noteIndex”:0},”citationItems”:{“id”:73,”uris”:”http://zotero.org/users/4612010/items/EUGSFNGP”,”uri”:”http://zotero.org/users/4612010/items/EUGSFNGP”,”itemData”:{“id”:73,”type”:”book”,”title”:”High Collection Nonimaging Optics – 1st Edition”,”publisher”:”Academic Press”,”URL”:”https://www.elsevier.com/books/high-collection-nonimaging-optics/welford/978-0-12-742885-7″,”author”:{“family”:”Winston”,”given”:”R.”},{“family”:”Welford”,”given”:”W.T.”},”accessed”:{“date-parts”:”2018″,1,17}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 28 ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a1ull9jev3t”,”properties”:{“formattedCitation”:”37″,”plainCitation”:”37″,”noteIndex”:0},”citationItems”:{“id”:114,”uris”:”http://zotero.org/users/4612010/items/Z4TG436H”,”uri”:”http://zotero.org/users/4612010/items/Z4TG436H”,”itemData”:{“id”:114,”type”:”webpage”,”title”:”The Effects of Nonuniform Illumination on the Electrical Performance of a Single Conventional Photovoltaic Cell”,”container-title”:”International Journal of Photoenergy”,”genre”:”Research article”,”abstract”:”Photovoltaic (PV) concentrators are a promising approach for lowering PV electricity costs in the near future. However, most of the concentrators that are currently used for PV applications yield nonuniform flux profiles on the surface of a PV module which in turn reduces its electrical performance if the cells are serially connected. One way of overcoming this effect is the use of PV modules with isolated cells so that each cell generates current that is proportional to the energy flux absorbed. However, there are some cases where nonuniform illumination also exists in a single cell in an isolated cells PV module. This paper systematically studied the effect of nonuniform illumination on various cell performance parameters of a single monocrystalline standard PV cell at low and medium energy concentration ratios. Furthermore, the effect of orientation, size, and geometrical shapes of nonuniform illumination was also investigated. It was found that the effect of nonuniform illumination on various PV cell performance parameters of a single standard PV cell becomes noticeable at medium energy flux concentration whilst the location, size, and geometrical shape of nonuniform illumination have no effect on the performance parameters of the cell.”,”URL”:”https://www.hindawi.com/journals/ijp/2015/631953/abs/”,”note”:”DOI: 10.1155/2015/631953″,”language”:”en”,”author”:{“family”:”Paul”,”given”:”Damasen Ikwaba”},{“family”:”Smyth”,”given”:”Mervyn”},{“family”:”Zacharopoulos”,”given”:”Aggelos”},{“family”:”Mondol”,”given”:”Jayanta”},”issued”:{“date-parts”:”2015″},”accessed”:{“date-parts”:”2018″,1,22}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 37 XV. Its effects are similar to partial shading. For a PV panel, differential illumination levels in the cells increases the series resistance losses. However, the most significant losses are at a string level when at least one of the series connected cells has a lower illumination level which reduces the current in the whole string ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a4fha6j7br”,”properties”:{“formattedCitation”:”37″,”plainCitation”:”37″,”noteIndex”:0},”citationItems”:{“id”:114,”uris”:”http://zotero.org/users/4612010/items/Z4TG436H”,”uri”:”http://zotero.org/users/4612010/items/Z4TG436H”,”itemData”:{“id”:114,”type”:”webpage”,”title”:”The Effects of Nonuniform Illumination on the Electrical Performance of a Single Conventional Photovoltaic Cell”,”container-title”:”International Journal of Photoenergy”,”genre”:”Research article”,”abstract”:”Photovoltaic (PV) concentrators are a promising approach for lowering PV electricity costs in the near future. However, most of the concentrators that are currently used for PV applications yield nonuniform flux profiles on the surface of a PV module which in turn reduces its electrical performance if the cells are serially connected. One way of overcoming this effect is the use of PV modules with isolated cells so that each cell generates current that is proportional to the energy flux absorbed. However, there are some cases where nonuniform illumination also exists in a single cell in an isolated cells PV module. This paper systematically studied the effect of nonuniform illumination on various cell performance parameters of a single monocrystalline standard PV cell at low and medium energy concentration ratios. Furthermore, the effect of orientation, size, and geometrical shapes of nonuniform illumination was also investigated. It was found that the effect of nonuniform illumination on various PV cell performance parameters of a single standard PV cell becomes noticeable at medium energy flux concentration whilst the location, size, and geometrical shape of nonuniform illumination have no effect on the performance parameters of the cell.”,”URL”:”https://www.hindawi.com/journals/ijp/2015/631953/abs/”,”note”:”DOI: 10.1155/2015/631953″,”language”:”en”,”author”:{“family”:”Paul”,”given”:”Damasen Ikwaba”},{“family”:”Smyth”,”given”:”Mervyn”},{“family”:”Zacharopoulos”,”given”:”Aggelos”},{“family”:”Mondol”,”given”:”Jayanta”},”issued”:{“date-parts”:”2015″},”accessed”:{“date-parts”:”2018″,1,22}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 37 I IV. This lower illumination level is often cause by shading from the collectors´ box frame or the lack of reflector. In other words, in a stationary CPC, the transversal shading impacts all cells in a string and does not cause one cell to have more current than another which means that the losses are almost proportional to the shaded area. On the other hand, the longitudinal shading causes the edge cells to receive a lower illumination than the rest of the series connected cells greatly amplifying the effect of shading.

This way, non uniform illumination is considerably more critical for PV panels than for solar thermal.

The analyzed PVT design includes a CPC concentrator. For this reason, the study on shading was mainly focused on the electrical part of an asymmetric compound parabolic concentrating (CPC) photovoltaic/thermal hybrid (PVT).
First Look at the Solarus C-PVTOver time, Solarus has developed several versions of its C-PVT, many of which have been analyzed during this thesis. For simplicity, this section will only detail the latest version of the Solarus collector which called Power Collector (PC) ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a10q2vus9u6″,”properties”:{“formattedCitation”:”38″,”plainCitation”:”38″,”noteIndex”:0},”citationItems”:{“id”:61,”uris”:”http://zotero.org/users/4612010/items/9DJWKIA7″,”uri”:”http://zotero.org/users/4612010/items/9DJWKIA7″,”itemData”:{“id”:61,”type”:”webpage”,”title”:”Solarus Sunpower Website”,”container-title”:”Solarus”,”URL”:”http://solarus.com/”,”language”:”en-US”,”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 38. The figure below shows the PC:
Figure SEQ Figure * ARABIC 22: The latest version of the Solarus C-PVT, the Power CollectorHowever, all versions of the Solarus C-PVT solar collector can be divided into two defining main components: The collector box and the PVT receiver, both of which are presented in the next chapters.

The Collector BoxThe figure below shows a breakdown of all components of the collector.

Figure SEQ Figure * ARABIC 23: Solarus C-PVT PC components profile.The collector box has four main components:
A black plastic solid frame that provide structural support to the reflector;
A gable with a reported 90% of transparency and that is made from Polymethylmethacrylate (commonly known as PPMA) that seals the collector sides as shown on the picture below;
Figure SEQ Figure * ARABIC 24: Profile view of the Solarus C-PVT showing the transparent gable and the black plastic frame.A 4mm tempered solar glass with anti-reflective treatment (on both sides) to reach a 1.5% absorptance and 2% of reflectance per side;
A 0.4mm aluminium reflector with a reflectance is 92 % of reflectance at an air mass of 1.5, according to the standard. The reflector geometry is a variation of the roof integrated Maximum Reflector Concentration (MaReCo). As shown in the figure below. The concentration factor is 1.7.

Figure SEQ Figure * ARABIC 25: Cross section of the MaReCo collector ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a4cubi1vta”,”properties”:{“formattedCitation”:”29″,”plainCitation”:”29″,”noteIndex”:0},”citationItems”:{“id”:71,”uris”:”http://zotero.org/users/4612010/items/XQPWU6FF”,”uri”:”http://zotero.org/users/4612010/items/XQPWU6FF”,”itemData”:{“id”:71,”type”:”book”,”title”:”Solar Thermal Collectors at High Latitudes Design and Performance of Non-Tracking Concentrators”,”publisher”:”Uppsala University”,”volume”:”PhD Thesis”,”source”:”ResearchGate”,”abstract”:”ABSTRACT Adsten, M. 2002. Solar thermal collectors at high latitudes -Design and performance of non- tracking concentrators. Acta Universitatis Upsaliensis. Comprehensive,Summaries of Uppsala Dissertations from the Facultyof Science and Technology 697. 78 pp. Uppsala. ISBN 91-554- 5274-4 Solar thermal collectors at high latitudes have been studied, with emphasis on concentrating collectors. A novel design of concentrating collector, the Maximum Reflector Collector (MaReCo), especially designed for high latitudes, has been investigated optically and thermally. The MaReCo is an asymmetrical,compound,parabolic concentrator with a bi-facial absorber. The collector can be adapted to various installation conditions, for example stand- alone, roof- or wall mounted. MaReCo prototypes have been built and outdoor-tested. The evaluation showed ,that all types work ,as expected ,and that the highest annually delivered energy output, 340 kWh/m,, is found for the roof MaReCo. A study of the heat-losses from the stand-alone MaReCo lead to the conclusion that ,teflon transparent insulation should be placed around the absorber, which decreases the U-value by about 30%. A method was developed to theoreticallystudy the projected radiation distribution incident onthe,MaReCo bi-facial absorber. The study showed ,that the geometry ,of the ,collectors could be improved ,by slight ,changes in the ,acceptance intervals. It also indicated that the MaReCo design concept could be used ,also at mid-European ,latitudes if the geometry ,is changed. Anovel,method ,was ,used to perform ,outdoor measurements ,of the ,distribution of concentrated light on the ,absorber and then to calculate ,the annually collected ,zero-loss energy, Ea,corr, together with the annual optical efficiency factor. A study using this method indicated that the absorber should be mounted,along the 20° optical axis instead of along,the”,”author”:{“family”:”Adsten”,”given”:”Monika”},”issued”:{“date-parts”:”2002″,1,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 29
Receiver coreThe receiver core is the heart of the Solarus C-PVT. It has 2321 mm long, 165 mm wide and 14.5 mm thickness. As shown below, there are solar cells on both sides of the aluminum receiver. These solar cells are encapsulated by a highly transparent silicone with a reported transparency of 97%.
Figure SEQ Figure * ARABIC 26: Solarus bifacial receiverThe receiver consists on an aluminum receiver with 8 elliptical channels as shown in the figure above. The cooling fluid flows through the 8 channels in order to extract heat from the collector. The core is made of extruded aluminum.

Figure SEQ Figure * ARABIC 27: Side view of the receiver core showing the 8 elliptical channels. Dimensions in mm.The collector uses standard monocrystalline solar silicon cells with and efficiency of 19.7%. The cell string layout consists in 4 cells strings in the bottom and 4 in the top side of the receiver. This is shown in the figure below:
Figure SEQ Figure * ARABIC 28: Receiver, showing 4 cell strings and its distribution in the receiver.Each side of the receiver has 38 cells, and each receiver has 76 cells. Each collector has 152 cells. The dimension of each cell is 52 mm length, 156 mm height and 0.2 mm of thickness, with a nominal efficiency of 19.7%. The manufacturer obtains these cells by cutting standard size cells (156mm*156mm) into three pieces with the same size. The reasons for this is to reduce the current in the strings, which reduces the resistance losses, being that the losses in ribbons that connect the cells is particularly important for the performance.

-27800302012950
Figure SEQ Figure * ARABIC 29: Two images showing general aspects of the Solarus C-PVT technology ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a1s59i6kbvv”,”properties”:{“formattedCitation”:”38″,”plainCitation”:”38″,”noteIndex”:0},”citationItems”:{“id”:61,”uris”:”http://zotero.org/users/4612010/items/9DJWKIA7″,”uri”:”http://zotero.org/users/4612010/items/9DJWKIA7″,”itemData”:{“id”:61,”type”:”webpage”,”title”:”Solarus Sunpower Website”,”container-title”:”Solarus”,”URL”:”http://solarus.com/”,”language”:”en-US”,”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 38
Systems Integration of the Solarus C-PVTSolarus produces heat and electricity as therefore requires costumers that have a need for both. The simplest system in which a Solarus collector can be utilized is for example in a hotel using the heat to cover the DHW demand and feeding the electricity to the grid for a fee. Solarus is today focusing mainly in this market. However, other systems are possible. The figure below shows a system that can produce heat, cooling and electricity.

Figure SEQ Figure * ARABIC 30: Sketch of a possible Solarus system proving heat, cooling and electricity to a household ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a1ph68rh2qg”,”properties”:{“formattedCitation”:”38″,”plainCitation”:”38″,”noteIndex”:0},”citationItems”:{“id”:61,”uris”:”http://zotero.org/users/4612010/items/9DJWKIA7″,”uri”:”http://zotero.org/users/4612010/items/9DJWKIA7″,”itemData”:{“id”:61,”type”:”webpage”,”title”:”Solarus Sunpower Website”,”container-title”:”Solarus”,”URL”:”http://solarus.com/”,”language”:”en-US”,”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 38
Besides these three applications, the manufacturer is looking into options to provide three other applications: (i) steam; (ii) desalination; (iii) water purification.

Figure SEQ Figure * ARABIC 31: Possible applications for the PC ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a15vrponvcb”,”properties”:{“formattedCitation”:”38″,”plainCitation”:”38″,”noteIndex”:0},”citationItems”:{“id”:61,”uris”:”http://zotero.org/users/4612010/items/9DJWKIA7″,”uri”:”http://zotero.org/users/4612010/items/9DJWKIA7″,”itemData”:{“id”:61,”type”:”webpage”,”title”:”Solarus Sunpower Website”,”container-title”:”Solarus”,”URL”:”http://solarus.com/”,”language”:”en-US”,”accessed”:{“date-parts”:”2018″,1,8}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 38

PVT Market OverviewConsider to Include also large picture with comparison simulation done or exclude this table
This table could contain a summary of the information from the two large papers on PVT

Method OverviewA combination of complementary methods was used in order to answer the research questions.The main method utilized was performance testing on a large array of different C-PVT collector prototypes that were built for this thesis. The collector testing results was complemented with three types of simulations:
Winsun in order to obtain the annual output;
Raytracing with Tonatiuh for characterizing the current reflector and comparing different reflector geometries;
LTSpice for analyzing the impact of different string layouts.
Additionally a market survey was conducted and a new ratio was defined as a way to compare different collectors.

WinsunMethodDefinition of the ratio between ST and PVAlthough PV and ST produce different types of energy, they are often competing among themselves. This is not just because the investment capacity is limited as but also because of limitations in other factors such as the energy demand and roof space. Additionally, as mentioned in paper 1, “electricity can be converted into heat and vice-versa. However, electricity can be converted into heat at an efficiency of almost 100% while heat conversion into electricity has a much lower efficiency and requires more complex equipment”.

The previously described large climate variations around the world lead to significant differences in the performance of solar systems around the globe. Moreover, each type of solar system has a different response to these variations.

Therefore, it makes sense to develop a ratio that quantifies the difference in annual energy output between standard solar thermal collectors and PV panels for different locations. This ratio is useful, for example, to support the decision between installing ST or PV, when combined with other local specific information such as the value of heat and electricity for a specific location and application, the system complexity and efficiency, and even factors such as the knowledge of local installers knowledge or the available offer. This ratio was defined, as following:
Ratio Between ST and PV=Annual Energy Output per m2 of ST collectorAnnual Energy Output per m2 of PV panel (eq. 3)
This ratio was calculated for the different solar systems based on the results obtained from a market analysis. Two types of PV panels were considered: average monocrystalline and polycrystalline panels. Two main types of ST panels were considered: Flat Plate and Vacuum Tube. Additionally, for ST collectors, the following collector average temperatures were investigated: 30ºC, 50ºC and 80ºC.

The annual energy outputs in the above ratio were obtained through Winsun simulations.

This ratio was then calculated and plotted on the world map for a clear visualization. The three above mentioned temperatures were plotted but only the middle temperature (50ºC) is shown since it was found to be the most relevant one.

Market surveyA detailed market survey was carried out to investigate the prices and standard panel characteristics for both PV and ST in January of 2014. The ST survey included a total of 90 collectors of 3 types: flat plate, vacuum tube with flat absorber, vacuum tube with round absorber. This survey comprised 43 companies in 16 countries. All collectors were tested according to the standard EN 12975 11 and an average was made.
The PV survey looked into 150 different PV panels from 35 companies of 9 countries.
Winsun SimulationsWinsun is a TRNSYS based solar simulation software that was developed by Bengt Perers and Björn Karlsson at Lund University. Winsun can simulate both the annual performance of an ST or PV panel. The inputs and outputs of the program are described in the figure below. A new collector file was made for Winsun based on the market survey findings regarding the standard collector characteristics per aperture area. The values for efficiency and heat losses were taken from the market study and are presented in the results. For all performed simulations, the collector was stationary at a tilt equal to the latitude of the selected city. Simulations were performed for 66 cities around the world in a range of different latitudes and climatic regions in order to obtain a good visualization of the variation of the ratio in the world map.

Figure 32: Winsun’s inputs and outputs ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”at25b45fjv”,”properties”:{“formattedCitation”:”39″,”plainCitation”:”39″,”noteIndex”:0},”citationItems”:{“id”:99,”uris”:”http://zotero.org/users/4612010/items/6WW3FTS2″,”uri”:”http://zotero.org/users/4612010/items/6WW3FTS2″,”itemData”:{“id”:99,”type”:”article-journal”,”title”:”Smart district heating networks – A simulation study of prosumers’ impact on technical parameters in distribution networks”,”container-title”:”Applied Energy”,”page”:”39-48″,”volume”:”129″,”source”:”ScienceDirect”,”abstract”:”Environmental awareness increases, with demands for environmental certifications of new communities and buildings as a result. In the district heating industry, enabling of decentralized energy production is one way to meet requirements from customers. In this paper the technical impact of small-scale local solar collectors and heat pumps on district heating distribution networks is investigated. Customers that in this way can both produce and consume district heating are in this paper called prosumers. The study has mainly been performed through simulations in the computer programme NetSim. The results show that since the supply temperature from prosumers often is lower than the typical supply temperature, contribution from prosumers may result in lower supply temperature and thus increased velocity. The differential pressure decreases when water from the prosumers is mixed with supply water from the rest of the network and increases in the area where the prosumer creates a new pressure cone. Areas that are not reached by water from prosumers are affected differently depending on how the control of the differential pressure is managed. The results also show that prosumers’ lower supply temperature may cause migratory temperature fronts that lead to increased fatigue in the pipes. This was further investigated by the local district heating company and the result showed that migratory temperature fronts generally has little impact on the lifetime of the pipes, since corrosion remains to be the limiting factor. In summary, this paper indicates that introduction of prosumers is possible, but demands management and control.”,”DOI”:”10.1016/j.apenergy.2014.04.079″,”ISSN”:”0306-2619″,”journalAbbreviation”:”Applied Energy”,”author”:{“family”:”Brand”,”given”:”Lisa”},{“family”:”Calvén”,”given”:”Alexandra”},{“family”:”Englund”,”given”:”Jessica”},{“family”:”Landersjö”,”given”:”Henrik”},{“family”:”Lauenburg”,”given”:”Patrick”},”issued”:{“date-parts”:”2014″,9,15}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 39 IWinsun was used to simulate the performance of PV and ST panels over the year and provide the annual output per m2 of aperture area.

The following formulas are used by the winsun to calculate the annual output:
Q=?0b?Kb??Gb+?0b?Kdiffuse?Gd-U1Tm-Ta-U2Tm-Ta² (eq. 4)
Kb?=1-b0?1cos?-1 (eq. 5)

ResultsMarket SurveyThe market studied, conducted in the first four months of the thesis in 2013, obtained the average performance values for solar thermal as described in the table below.

Table SEQ Table * ARABIC 3: Values for different T collectors expressed per absorber area, aperture area and gross area IType of Panel ABSORBER APERTURE GROSS
?0 (%) U1 (W/m²K) U2 (W/m²K) ?0 (%) U1 (W/m²K) U2 (W/m²K) ?0 (%) U1 (W/m²K) U2 (W/m²K)
Flat Plate 80,3 3,967 0,009 78,6 3,877 0,008 71,3 3,526 0,008
Vacuum with round absorber 74,1 2,088 0,009 64,4 1,809 0,008 39,9 1,117 0,005
Vacuum with flat absorber 82,0 1,626 0,004 74,0 1,468 0,003 54,9 1,085 0,003
A standard average efficiency was found for both polycrystalline and monocrystalline panels and is shown in the table below.

Table SEQ Table * ARABIC 4: Average efficiency for monocrystalline and polycrystalline modules IType of PV panel Efficiency
Monocrystalline 16,5%
Polycrystalline 14,6%
Finding out the price of the panels proved to be a more complex process than expected and some uncertainty lingered, as the price variations that were found were considerable large. The prices that our market survey found for PV were 15% lower than mentioned in the sites like PVXchange. ST prices were also found to vary substantially so a similar error margin exists. The following tables describe the prices that were found in the market study.

Table SEQ Table * ARABIC 5: Price of a ST collector in € per gross and aperture area IType of ST panel Flat Plate Vacuum Tube (Flat absorber) Relative differenceFP to VT
Sale with VAT (consumer) in €/m² gross 158 166 5%
Sale with VAT (consumer) in €/m² aperture 187 275 32%
Relative difference gross to aperture area 15% 40% –
Table SEQ Table * ARABIC 6: PV Price from cell to panel in €/Wp IType of PV panel Poly Mono Unit
Cell price 0,27 0,31 €/Wp
Panel sale price with VAT (consumer) 0,52 0,56 €/Wp
Price increase from cell to panel 1,93 1,81 –
Table 7: Price comparison PV to ST (including VAT) at consumer level in EU (custom cleared) IType of Solar panel Price €/m² aperture Comparison to Poly Comparison to VT
ST Flat Plate 187 179% 68%
ST Vacuum Tube with flat absorber 275 263% 100%
PV Polycrystalline 104 100% 38%
PV Monocrystalline 127 122% 46%
Winsun SimulationsThe annual energy output ratio between PV and ST was calculated for the 66 cities.

For all locations and for a working temperature of 50ºC, the ST panel always produces more energy than PV. As expected, this is also true for a ST operating temperature of 30ºC but at an operating temperature of 80ºC, there were two locations of this study (in Russia and Norway) where the flat plates were performing worse than PV. Unlike flat plates, vacuum tube performed better than PV in all simulated locations and temperatures due to a lower heat loss factor. Additionally, around the world, vacuum tubes normally outperform flat plate collector per aperture area for temperatures of 50ºC and 80ºC. However, for a temperature of 30ºC, the flat plate is sometimes outperforming the vacuum tube with flat absorber, especially in warm locations. This is due to the fact that flat plates have 5% higher peak efficiency.
The ration between PV and ST ratio was then plotted on the world map for a clear visualization. Since the most commonly used ST temperature is 50ºC, only this temperature was plotted. This way, four world maps were created. All maps show how much more energy the ST produces comparing to PV. In general, the ratio increases when the latitude decreases. Some examples of this ratio are shown below for 3 cities at 3 different latitudes: close to the Equator, Tropic of Capricorn and Arctic Circle line.

Table SEQ Table * ARABIC 8: Irradiance (kWh/m2), panel outputs (kWh/m2) and ratios ST/PV I
As shown in the above table, the ratio between a flat plate working at 50ºC and a polycrystalline PV panels varies considerably around the world. In Nairobi, a flat plate will produce 3.7 times more energy than a PV panel with 14.6% efficiency while for Rio de Janeiro this ratio is 3.8. These two cities are an example that the ratio does not always increase when moving towards the equator. In Umea, the ratio is considerably lower at 2.6.

Each legend in the map has the same scale for the next four maps. The scale goes from green (stronger ST location) to blue (weaker ST location). The black color is an extreme case which only happens in very specific situations.

Figure SEQ Figure * ARABIC 33: Ratio Flat plate 50°C to PV 14.6% polycrystalline IThe figure above shows the ratio between a flat plate collector working at an average temperature of 50°C and a polycrystalline module with an efficiency of 14.6%. The lowest ratio of 1.36 is found in REF _Ref508544737 h figure 34 the coldest place with the highest latitude. On the opposite end, the city of Dijbouti at latitude of 12° reaches a ratio of 4.46 signaling a high over-performance of ST facing PV.
Singapore is an exception, since it has a considerably lower ratio than the other cities at similar latitudes. This is mostly caused by a long duration of a cloudy rain season, which also lowers the ratio of beam to total radiation as shown previously. All four maps show that for locations with high diffuse radiation or low ambient temperature, the ratio goes down which means that ST is producing less energy in comparison to the PV.

Figure SEQ Figure * ARABIC 34: Ratio Flat plate 50°C to PV 16.4% monocrystalline I REF _Ref508544737 h Figure 34 shows the annual energy output ratio between a flat plate working at 50ºC and a monocrystalline PV with 16.4% of efficiency. The ratios above REF _Ref508544737 h figure 34 are lower than in REF _Ref508544767 h figure 33, since monocrystalline modules have a higher efficiency than the polycrystalline. The ratio from ST to mono is always around 88% of the ratio of ST to poly. This happens for both vacuum tubes and flat plates collectors.

Figure SEQ Figure * ARABIC 35: Ratio Vacuum tube with flat absorber 50°C to PV 14.6% polycrystalline IAs expected, the ratio between vacuum tube with flat absorber and the poly modules show the highest ratio values in all four maps. For a ST working temperature of 50ºC, the highest ratio value was found to be 4.76 in Dijbouti, a city located close to the equator with a warm average temperature of 30°C.

The lowest ratio in REF _Ref508544800 h Figure 35 is 3.06 which is considerably higher than the lowest ratio found in REF _Ref508544767 h figure 33 that shows the ratio between flat plate and polycrystalline PV which is 1.54. This is mainly explained by the extremely low temperatures in this location combined with the fact that vacuum tubes have lower heat losses than standard flat plates. In between latitudes of 40ºN and 40ºS, all ratios on the map are above 4.2.
Figure SEQ Figure * ARABIC 36: Ratio Vacuum tube with flat absorber 50°C to PV 16.4% monocrystalline IFrom the four maps shown in the paper, REF _Ref508545038 h figure 36 has the smallest variation between the highest and lowest ratio. This variation is 1.5. The highest ratio found was 4.21 which is lower than the highest ratio between flat plate to poly which is 4.46. In all maps, the lowest ratio is always Cape Zhelaniya (Russia) while the highest ratio of the graph is in Dijbouti.
ConclusionA market survey was conducted that determined the average performance and price values for a few types of ST and PV panels. These performance values were then used to simulate the annual energy output of each type of panel. This was the basis for establishing a qualitative comparison between ST and PV panels, the annual energy output ratio. In order to facilitate the interpretation of those results, several world maps were drawn to graphically show the differences in annual energy production of the different solar technologies in different locations.
On a world scale, this ratio tends to increase at lower latitudes which is clearly visible in the four previous figures. This happens despite large variation being introduced by local climate. The higher ratios at low latitudes mean that ST panels are performing comparatively better than PV and the inverse for higher latitudes. Two main factors are responsible for this:
The efficiency of a PV panel is reduced with the increase of air temperature while in solar thermal the opposite effect takes place.

Under low intensity solar irradiance, the efficiency of a PV panel is maintained while a solar thermal collector might not reach the required operating temperatures and have an output of zero.

The ratio maps allow reaching the following conclusions:
For all locations and for a working temperature of 50ºC, the ST panel always produces more energy than PV.

Around the world, vacuum tubes with flat absorber normally outperform flat plate collectors per aperture area for temperatures of 50ºC and 80ºC. However, the price per aperture area of vacuum tube with flat absorber is also 32% higher than flat plate. This means that, assuming that the installation cost is the same for both ST technologies, vacuum tubes should be preferred only, if its annual output is higher than a flat plate annual output by 32%.

For a temperature of 30ºC, the flat plate is sometimes outperforming the vacuum tube with flat absorber, namely in warm locations.

All four maps show that for locations with high diffuse radiation or low ambient temperature, the ratio goes down meaning that ST is producing less energy in relation to the PV.

For latitudes lower than 66º, the ratio flat plate at 50ºC to PV is ranging from 1,85 to 4,46 while in the ration between vacuum tube at 50ºC and PV from 3,05 to 4,76. These numbers can be an important tool when making the decision of going for PV or ST. However, it is important not to forget that dimensioning ST installations so that all the energy is utilized is key in generating good revenue from projects.

The ratio was also calculated for ST operating temperatures of 30ºC and 80ºC. As expected, the ratio goes up for 30ºC (meaning that it is more favorable to ST) and goes down for 80ºC (meaning that it is less favorable for ST).

The ratio for ST to monocrystalline is always around 88% of the ratio of ST to poly. This happens for both vacuum tubes and flat plate collectors.

Collector testingTesting is an essential step in order to be able to evaluate solar collectors. This section describes the different collector prototypes that were tested as well as the equipment at the different locations where the collectors were tested and the tests that were conducted at each location.

Collector Testing MethodKey thermal parameters to test in a low concentration C-PVTSolar collector characterization relies on two main testing methodologies: Quasi Dynamic Testing (QDT) and Steady State (SS). During this thesis, both methods were used to characterize the different prototypes that were tested.

According to Petterson et al ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a10bqm956go”,”properties”:{“formattedCitation”:”40″,”plainCitation”:”40″,”noteIndex”:0},”citationItems”:{“id”:145,”uris”:”http://zotero.org/users/4612010/items/H3QECPIV”,”uri”:”http://zotero.org/users/4612010/items/H3QECPIV”,”itemData”:{“id”:145,”type”:”article-journal”,”title”:”Improving the compatibility between steady state and quasi dynamic testing for new collector designs”,”source”:”Google Scholar”,”author”:{“family”:”Pettersson”,”given”:”U.”},{“family”:”Kovács”,”given”:”P.”},{“family”:”Perers”,”given”:”B.”}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 40, QDT method offers the following advantages over SS:
“It allows for accurate characterization of a wide range of collector types;
It allows for testing under a wide range of operating and ambient conditions;
It gives a more complete characterization of the collector through an extended parameter set as compared to steady state testing.”
However according to Afonso el al ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a2mgdc0hc38″,”properties”:{“formattedCitation”:”41″,”plainCitation”:”41″,”noteIndex”:0},”citationItems”:{“id”:148,”uris”:”http://zotero.org/users/4612010/items/PU8F8UBF”,”uri”:”http://zotero.org/users/4612010/items/PU8F8UBF”,”itemData”:{“id”:148,”type”:”article-journal”,”title”:”Comparison between Steady State and Quasi -Dynamic test Method according to EN 12975 – Application to flat plate collectors .”,”container-title”:”Eurosun 2008″,”author”:{“family”:”Afonso”,”given”:”J.”},{“family”:”Mexa”,”given”:”N”},{“family”:”Carvalho”,”given”:”M”},”issued”:{“date-parts”:”2008″}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 41, “applying QDT can be difficult in other locations where the weather is very stable or where diffuse fractions are constantly very low”.

Other sources such as Fisher et al ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a206p571c4g”,”properties”:{“formattedCitation”:”42″,”plainCitation”:”42″,”noteIndex”:0},”citationItems”:{“id”:149,”uris”:”http://zotero.org/users/4612010/items/2IMZ3HUS”,”uri”:”http://zotero.org/users/4612010/items/2IMZ3HUS”,”itemData”:{“id”:149,”type”:”article-journal”,”title”:”Collector test method under quasi-dynamic conditions according to the European Standard EN 12975-2″,”container-title”:”Solar Energy”,”page”:”117–123″,”volume”:”76″,”issue”:”1-3″,”source”:”Google Scholar”,”author”:{“family”:”Fischer”,”given”:”S.”},{“family”:”Heidemann”,”given”:”W.”},{“family”:”Müller-Steinhagen”,”given”:”H.”},{“family”:”Perers”,”given”:”Bengt”},{“family”:”Bergquist”,”given”:”P.”},{“family”:”Hellström”,”given”:”Bengt”},”issued”:{“date-parts”:”2004″}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 42 or Carvalho et al ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”ATgNzn6L”,”properties”:{“formattedCitation”:”43″,”plainCitation”:”43″,”noteIndex”:0},”citationItems”:{“id”:153,”uris”:”http://zotero.org/users/4612010/items/I52A3J5S”,”uri”:”http://zotero.org/users/4612010/items/I52A3J5S”,”itemData”:{“id”:153,”type”:”chapter”,”title”:”Incidence Angle Modifiers: A General Approach for Energy Calculations”,”container-title”:”Proceedings of ISES World Congress 2007 (Vol. I – Vol. V)”,”publisher”:”Springer, Berlin, Heidelberg”,”page”:”608-612″,”source”:”link.springer.com”,”abstract”:”The calculation of the energy (power) delivered by a given solar collector, requires special care in the consideration of the way it handles the incoming solar radiation. Some collectors, e.g. flat plate types, are easy to characterize from an optical point of view, given their rotational symmetry with respect to the incident angle on the entrance aperture. This in contrast with collectors possessing a 2D (or cylindrical) symmetry, such as collectors using evacuated tubes or CPC collectors, requiring the incident radiation to be decomposed and treated in two orthogonal planes.Analyses of incidence angle modifier (IAM) along these lines were done in the past for parabolic through, evacuated tube (ETC) or compound parabolic concentrator (CPC) collectors 1-6.The present paper addresses a general approach to IAM calculation, treating in a general, equivalent and systematic way all collector types.This approach will allow the proper handling of the solar radiation available to each collector type, subdivided in its different components, folding that with the optical effects present in the solar collector and enabling more accurate comparisons between different collector types, in terms of long term performance calculation.”,”URL”:”https://link.springer.com/chapter/10.1007/978-3-540-75997-3_112″,”ISBN”:”978-3-540-75996-6″,”note”:”DOI: 10.1007/978-3-540-75997-3_112″,”shortTitle”:”Incidence Angle Modifiers”,”language”:”en”,”author”:{“family”:”Carvalho”,”given”:”Maria João”},{“family”:”Horta”,”given”:”Pedro”},{“family”:”Mendes”,”given”:”João Farinha”},{“family”:”Pereira”,”given”:”Manuel Collares”},{“family”:”Carbajal”,”given”:”Wildor Maldonado”},”issued”:{“date-parts”:”2008″},”accessed”:{“date-parts”:”2018″,3,12}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 43 et al concur with the above statements.

In the QDT method some of the boundary conditions parameters are kept strictly steady (flow rate and inlet temperature), while other parameters are left freely dynamic with only minor limit constraints. Paper XXII utilizes QDT to characterize a standard flat plate thermal collector and the Solarus C-PVT. The equation utilized was adapted from the ISO 9806:2013 and is detailed below:
QA=F’??K?b?L,?TGb+F’??K?dGd-C1tm-ta-C2tm-ta2 (eq. 1)
-C3utm-ta+C4EL-?Ta4-C5dtmdt-C6uGThe required input parameters for a successful characterization using the above formula are:
Total irradiation; beam irradiation fraction; diffuse irradiation fraction; mean temperature of the collector; ambient temperature; wind speed; long wave irradiation; mean collector temperature change over time; and the power output of the collector.

For the case of glazed collectors, however, it is often recommended that the wind speed and the long wave radiation are omitted since their impact on the absolute losses and gains is negligible. In paper XXII, two of the input parameters have been kept steady throughout the testing, the flow rate and the inlet fluid temperature, while the rest were allowed to change freely.
The tool used for the parameter identification is the Multiple Liner Regression (MLR), this statistical model identifies the equation factors that best describe the collector based on how closely the produced equation can reproduce the collector power output accurately.

The following list summarizes the main terms commonly used to define a solar thermal collector:
F´(??): zero loss efficiency of the collector for beam radiation, at normal incidence angle;
K?b(?L,?T): incidence angle modifier for beam solar radiation. K?b varies with the incidence angles ?L, and ?T;
K?d: incidence angle modifier for diffuse solar radiation;
c1 : heat loss coefficient at (tm – ta) = 0 (also mentioned as U1 in literature) ;
c2 : temperature dependence in the heat loss coefficient (also mentioned as U2 in literature);
c3 : wind speed dependence of the heat losses;
c4 : long wave irradiance dependence of the heat losses;
c5 : effective thermal capacitance;
c6 : wind dependence of the collector zero loss efficiency;
SS testing, on the other hand, keeps all parameters in steady state under a narrow range. The Elforsk report ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a2j8ga9l3tf”,”properties”:{“formattedCitation”:”44″,”plainCitation”:”44″,”noteIndex”:0},”citationItems”:{“id”:152,”uris”:”http://zotero.org/users/4612010/items/D2NKEFDL”,”uri”:”http://zotero.org/users/4612010/items/D2NKEFDL”,”itemData”:{“id”:152,”type”:”article”,”title”:”Development of a Hybrid MaReCo Solar Panel”,”publisher”:”Elforsk”,”author”:{“family”:”Gomes”,”given”:”J.”},{“family”:”Stenlund”,”given”:”N.”},{“family”:”Larsson”,”given”:”S.”},{“family”:”Karlsson”,”given”:”B.”},”issued”:{“date-parts”:”2011″}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 44 utilizes the SS method to characterize the first C-PVT prototype built by Solarus which was tested by the author at Lund University. The following formula was used to obtain the thermal power from the measured collector:
P = (Tout – Tin) * Specific heat of water (Cp) * Density of water (?) * Flow / Area of collector (eq. 2)
An important number for collectors is the stagnation temperature. Stagnation temperature is often defined, as the temperature reached by the solar thermal collector under no flow, 1000W/m2 of solar radiation and ambient temperature of 40°C. At stagnation, all incoming solar radiation becomes heat losses from the collector. This number is often used to define the heat resistance properties that the solar collector must possess in order to survive stagnation. Stagnation commonly occurs after the malfunctioning of a pump or controller in a solar thermal system during a sunny day.
Key electrical parameters to test in a low concentration C-PVTThe most important electrical parameter to describe a PV panel are peak power (Pmp). Cell temperature dependence is usually given by the manufacturers but it can also be measured. Parameters such as short circuit current (Isc), maximum power current (Imp), maximum power voltage (Vmp) or open current voltage (Voc) are also important. As of 2018, common peak power of a silicone module range between 200 to 350W for an area of 1.6m2. The cell temperature dependence characterizes the variation in power, efficiency, current or voltage that a solar cell or PV panel undergoes with the change of temperature. For efficiency, in a silicone solar cell, this coefficient often ranges +0.3 to 0.5%/°K ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”eE3R13eP”,”properties”:{“formattedCitation”:”18″,”plainCitation”:”18″,”noteIndex”:0},”citationItems”:{“id”:38,”uris”:”http://zotero.org/users/4612010/items/KYQX6UCB”,”uri”:”http://zotero.org/users/4612010/items/KYQX6UCB”,”itemData”:{“id”:38,”type”:”book”,”title”:”Applied Photovoltaics”,”publisher”:”Routledge”,”publisher-place”:”London ; Sterling, VA”,”number-of-pages”:”330″,”edition”:”2nd edition”,”source”:”Amazon”,”event-place”:”London ; Sterling, VA”,”abstract”:”A reliable, accessible and comprehensive guide for students of photovoltaic applications and renewable energy engineering. This thoroughly considered textbook from a group of leading influential and award-winning authors is brimming with information and is carefully designed to meet the needs of its readers. Along with exercises and references at the end of each chapter, the book features a set of detailed technical appendices that provide essential equations, data sources and standards. Starting from basics with ‘The Characteristics of Sunlight’ the reader is guided step-by-step through semiconductors and p-n junctions; the behaviour of solar cells; cell properties ad design; and PV cell interconnection and module fabrication. The book covers stand-alone photovoltaic systems; specific purpose photovoltaic systems; remote are power supply systems; and grid-connected photovoltaic systems. There is also a section on photovoltaic water pumping system components and design. Applied Photovolatics is well illustrated and readable with an abundance of diagrams and illustrations, and will provide the reader with all the information needed to start working with photovoltaics.”,”ISBN”:”978-1-84407-401-3″,”language”:”English”,”editor”:{“family”:”Wenham”,”given”:”Stuart R.”},{“family”:”Green”,”given”:”Martin A.”},{“family”:”Watt”,”given”:”Muriel E.”},{“family”:”Corkish”,”given”:”Richard”},”issued”:{“date-parts”:”2006″,12,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 18.

Both the standard for flat PV panels (IEC 61215) and the standard for concentrated panels (IEC 62108), specify that peak power of a PV panel must be measured at Standard Test Conditions (STC) which are defined as ambient temperature of 25°C, 1000W/m2 of solar radiation, air mass of 1.5 and no wind speed.

These tests are generally performed outside but they can also be done in a solar simulator. However, it is difficult to accurately simulate the solar spectrum since the sun is a very distant mass at a very high temperature.

Incidence angle modifierThe incidence angle modifier (IAM) is a key parameter to define for any stationary collector but it is especially important for concentrating collectors and even more relevant for stationary asymmetric concentrating collectors, as the Solarus Power Collector.

According to Carvalho et al ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”sWHfjxkt”,”properties”:{“formattedCitation”:”43″,”plainCitation”:”43″,”noteIndex”:0},”citationItems”:{“id”:153,”uris”:”http://zotero.org/users/4612010/items/I52A3J5S”,”uri”:”http://zotero.org/users/4612010/items/I52A3J5S”,”itemData”:{“id”:153,”type”:”chapter”,”title”:”Incidence Angle Modifiers: A General Approach for Energy Calculations”,”container-title”:”Proceedings of ISES World Congress 2007 (Vol. I – Vol. V)”,”publisher”:”Springer, Berlin, Heidelberg”,”page”:”608-612″,”source”:”link.springer.com”,”abstract”:”The calculation of the energy (power) delivered by a given solar collector, requires special care in the consideration of the way it handles the incoming solar radiation. Some collectors, e.g. flat plate types, are easy to characterize from an optical point of view, given their rotational symmetry with respect to the incident angle on the entrance aperture. This in contrast with collectors possessing a 2D (or cylindrical) symmetry, such as collectors using evacuated tubes or CPC collectors, requiring the incident radiation to be decomposed and treated in two orthogonal planes.Analyses of incidence angle modifier (IAM) along these lines were done in the past for parabolic through, evacuated tube (ETC) or compound parabolic concentrator (CPC) collectors 1-6.The present paper addresses a general approach to IAM calculation, treating in a general, equivalent and systematic way all collector types.This approach will allow the proper handling of the solar radiation available to each collector type, subdivided in its different components, folding that with the optical effects present in the solar collector and enabling more accurate comparisons between different collector types, in terms of long term performance calculation.”,”URL”:”https://link.springer.com/chapter/10.1007/978-3-540-75997-3_112″,”ISBN”:”978-3-540-75996-6″,”note”:”DOI: 10.1007/978-3-540-75997-3_112″,”shortTitle”:”Incidence Angle Modifiers”,”language”:”en”,”author”:{“family”:”Carvalho”,”given”:”Maria João”},{“family”:”Horta”,”given”:”Pedro”},{“family”:”Mendes”,”given”:”João Farinha”},{“family”:”Pereira”,”given”:”Manuel Collares”},{“family”:”Carbajal”,”given”:”Wildor Maldonado”},”issued”:{“date-parts”:”2008″},”accessed”:{“date-parts”:”2018″,3,12}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 43, for standard flat plate solar thermal collector, the IAM is commonly defined by the following equation:
K?b(?) = 1 – b0 ((1/cos ?i) – 1) (eq. 2)
As mentioned above, other collectors such as vacuum tubers or stationary concentrating collectors have more complex IAM profiles that need to be characterized with additional detail. A common resolution for IAM testing is 5° steps. Namely, the Solarus C-PVT has specific characteristics that are important to considering when measuring the IAM.
The IAM can be electrical or thermal. In order to measure the IAM, the collector´s electrical or thermal power is measured at different incidence angle, while making sure that the irradiation and the cell temperature remain constant. For the thermal IAM, the measurements must be spaced out in time to account for the thermal mass.

Further details on the measuring methods of the IAM are given in chapter 5.3.2 and in paper VII.

Calculation of the theoretical maximum electrical powerThis chapter presents a theoretical calculation of the maximum electrical power of the collector. The calculations below represent an improvement over the calculations done in paper VII by adding further information like the transparency of silicone or the average number of bounces:
Pelectric_max=Pelectric_top_max+Pelectric_bottom_max(eq. 2)
Pelectric_max=110.5+159= 269.5 WPelectric_top_max=Acells_top×?silicone×?glass×cells_(25°C)×Gmax (eq. 2)
Pelectric_top_max=0.617×0.97×0.945×0.197×1000Pelectric_top_max=110.5 WPelectric_bottom_max=Pelectric_bottom_beam+Pelectric_bottom_diffuse (eq. 2)
Pelectric_max=149.2+9.8=159 WPel_bot_beam=C× Acells_bot×?silicone×?glass×(rref ×avgbounce) ×cells_(25°C)×Gb (eq. 2)
Pelectric_bottom_beam=1.7×0.617×0.97×0.945×0.92×0.883×0.197×900Pelectric_bottom_beam=149.2 WPel_bot_dif=C ×1C × Acells_bot×?silicone×?glass×(rref ×avgbounce) ×cells_(25°C)×Gdif(eq. 2)
Pelectric_bottom_diffuse=1.7× 11.7 × 0.617×0.97×0.945×0.883×0.197×100Pelectric_bottom_diffuse=9.8 WList of the different versions that have been testedWithin this thesis, a large number of prototype was tested. The table below lists the most relevant prototypes that were tested and gives a description of the key differences between them.

INSERT TABLE FROM EXCEL
Table SEQ Table * ARABIC 9: Collectors tested during this thesis
Testing at Lund UniversityThis section summarizes the testing of the first ever version of the Solarus C-PVT as well as a comparison to a stationary concentrating thermal collector also from Solarus. A full description can be found on the Elforsk report ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”a1ci2n5vmh4″,”properties”:{“formattedCitation”:”44″,”plainCitation”:”44″,”noteIndex”:0},”citationItems”:{“id”:152,”uris”:”http://zotero.org/users/4612010/items/D2NKEFDL”,”uri”:”http://zotero.org/users/4612010/items/D2NKEFDL”,”itemData”:{“id”:152,”type”:”article”,”title”:”Development of a Hybrid MaReCo Solar Panel”,”publisher”:”Elforsk”,”author”:{“family”:”Gomes”,”given”:”J.”},{“family”:”Stenlund”,”given”:”N.”},{“family”:”Larsson”,”given”:”S.”},{“family”:”Karlsson”,”given”:”B.”},”issued”:{“date-parts”:”2011″}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 44. Throughout this thesis, this prototype version will be named as V1.

Description of the prototype collectorThe figure below describes the V1 prototype C-PVT collector that was tested.

Figure SEQ Figure * ARABIC 37: Side and front views of the first Solarus C-PVT Prototype (V0) installed at Lund University
The glazed area of this prototype was 2.3 m2, which is a significant difference to the current version (PC). Effective solar thermal area was 2.18 m2.

Each receiver had 26 solar cell on each side. Each cell had the dimensions of 0.07 * 0.145 mm. This means that a string of 26 cells has 0.264 m2. The total cell area of the two receivers in the above figure totals: 4 * 0.264 = 1.06 m2. The effective glass area for electricity production equals 2 * 3 * 0.264 = 1.58 m2. The cells were soldered manually. Manual soldering causes more micro cracks than machine soldering.

The backside and the front side PV cells were connected in parallel. The top and the bottom receiver sides were also connected between themselves in parallel.

The geometric concentration factor of this reflector design is 3, however since there are solar cells on the front and back of the absorber the real concentration factor was 1.5. Concentration ratio for the front is 1, while the cells on the back receive 2 suns.

Figure SEQ Figure * ARABIC 38: Four Solarus stationary concentrating thermal collectors installed at Lund UniversityFour Solarus stationary concentrating thermal collectors were utilized as a comparison point to the C-PVT prototype and are thus named reference collectors. Both the reference and the C-PVT collector have the same of the box with the same reflector geometry as well as glazed area. The absorber of the reference collector has selective surface on both side and was produced by the company Sunstrip.

MethodTesting was conducted at the solar laboratory of Lund University. The main testing period was between 7th of May to 30th of May. Collector tilt was set 30° for both C-PVT and reference thermal collectors.

Thermal Testing:
The thermal testing method was SS, which was described in the previous chapter. The flow was set to 11 l/6m = 3.12 * 10-5 m3/s and kept constant throughout the full duration of the tests.
In order to produce the thermal efficiency curves, it was necessary to select two periods that are fully sunny days without any clouds so that the solar radiation remains constant. Additionally, these two periods have to be large enough to ensure that a thermal equilibrium point has been reached.

In each of these two days, the collector was supplied with pure water at a steady temperature with a variation no larger than 0.5°C. On the 20th of May, the collector was stable at low temperature (25°C) while, on the 26th of May, at a higher temperature (45°C). The following two graphs show that the global radiation remained very stable for the periods utilized for the thermal efficiency graphs.

Figure SEQ Figure * ARABIC 39: Global Solar Irradiance for the two measurement points of the thermal efficiencyFurthermore, an extra measurement was taken which was the night values for power at high and low inlet water temperatures. These measurement is a common technique for estimating the U-value of a collector, since the U-value is equal to the slope of the curve.

Electrical Testing:
The C-PVT V1 has two receivers as shown in the previous figure. On the bottom receiver, the measured values were for both the back side and the front side simultaneously. On the top receiver, the cables were reconnected in order to allowed performing individual measurements to just the backside or just the front side.
IV curves were continuously measured and recorded in a CR1000 logger. With each IV curve, Pmax, Isc, Imp, FF, Vmp and Voc were stored. These values were averaged for every 6 minute period.
ResultsThermal efficiency curves:
Using the two best periods, it was possible to obtain the following thermal efficiency graphs. These results are displayed in the figures below.

Figure SEQ Figure * ARABIC 40: Thermal Efficiency for the Solarus C-PVT V1 and reference thermal at I;900W/m2Night heat loss measurements:
The following figures were made based on all available night values and they allow estimating the U-value.

Figure SEQ Figure * ARABIC 41: Heat loss measurement during night time for the C-PVT V1 and for the reference thermalFrom the above figures, it is possible to extract the optical efficiency of both collectors and the global heat loss coefficient (U-value). As expected, the optical efficiencies of both collectors were identical but there was a large difference in heat losses, which are particularly visible at higher temperatures.

It is relevant to note again that the only difference between both collectors is the receiver. However while, V1 C-PVT possesses a non-selective string of PV cells encapsulated on a reflective aluminum receiver, the reference collector has a black selective absorber that greatly reduces the radiation heat losses. This is the reason for the reference collector about half of the U-value of the C-PVT V1.

Table REF _Ref518829899 h * MERGEFORMAT 10: Optical efficiency and measured heat losses of tested collectors
Reference Thermal Collector V1 of C-PVT
Optical Efficiency (%) 59.1 58.7
Global (day) U-value (W/m2, K) 2.92 5.19
Night U-value (W/m2, K) 2.25 4.22
Daily Thermal Power Curves:
The figure below shows the daily output and the mean fluid temperature of the reference thermal collector and the Solarus C-PVT V1 as well the global radiation.
Figure SEQ Figure * ARABIC 42: Global Radiation and average collector temperature plus power output for the Reference and V1 collector on 17th and 26th of MayDaily Electrical Power Curve:
A large number of electrical measurements have been performed and analyzed.

Figure SEQ Figure * ARABIC 43: Electrical power from the front and back side of the V1 collector during a clear day with high fraction of beam irradiance.The IV-curves in the figure above show that the front cells are working as expected at midday:
? = 45 / (1000 * 0.264) = 17.1%
The output of the backside is low at solar noon and decreases rapidly outside of this period. The efficiency in the middle of the day is:
? = 32.5 / (2 * 1000 * 0.264) = 6.2%
In order to calculate the efficiency of the backside cells, it is important to take into account the backside concentration of 2. The low efficiency at solar noon is due to optical losses in the reflector and uneven lighting. Outside of solar noon, falls rapidly outside of the side gables cast a shadow on the outermost cells which causes the whole string to stop working since the cells are series connected between themselves.

An analysis of the IV curves of the front cells results in a fill factor of 75%. This indicates that the absorber is able to successfully cool the cells. However the IV-curve for the backside cells at 12:24 when there is no shading due to the side gables results in a fill factor of 60%. The lower fill factor should be a result of uneven illumination of the cells. The focus line of an ideal reflector creates a varying irradiation over the cells but with the same overall irradiation on each cells. However, in reality, reflectors are not ideal and, thus, create different overall irradiation of the cells. Both these effects reduce the fill factor. The varying total irradiation between the cells has the greatest negative ie pact on the fill factor and performance. In addition, it is likely that the current capacity of the backside cells is reducing the backside output due to resistivity losses.
ConclusionsSolarus C-PVT V1 has been tested. Thermal performance has been quantified and compared to a reference thermal collector. Overall optical efficiency of both collectors are relatively low however the heat loss factor is also low. As expected, the optical efficiencies of both collectors are similar but the heat losses have a significant difference due to the lack of selective surface on the C-PVT V1. The higher heat losses will lead to a lower stagnation temperature, which in turn improves survivability and reduces material requirements. Due to the heat losses, the V1 collector is best suited for low to medium temperature applications. The V1 receiver also seems to have a higher inertia since its thermal power output tends to drop slower during the afternoon. Electrical measurements show the front side cells are working well which indicates that the receiver is able to successfully cool down the cells. Reflector losses and high current in the cells dictates a low peak power for the backside cells. Furthermore, the side shade from the gable has a very large impact on the daily power collector and needs to be prevented. Either some cells are removed for the edge of the strings or diodes are placed to bypass these cells outside of peak sun.

Lastly, the packing density should be increased to maximize the total electricity output.

Paper VII: Testing at Eduardo Mondlane UniversityTogether with colleagues from Lund University, the author has built from scratch a solar laboratory at Eduardo Mondlane University, in Maputo the capital of Mozambique. The construction of this solar laboratory is described in full detail in papers X and XII. The testing results from this laboratory are described in its fullest extent in paper VII and in report ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”IAHxJ3kB”,”properties”:{“formattedCitation”:”45″,”plainCitation”:”45″,”noteIndex”:0},”citationItems”:{“id”:158,”uris”:”http://zotero.org/users/4612010/items/NNF8FE6J”,”uri”:”http://zotero.org/users/4612010/items/NNF8FE6J”,”itemData”:{“id”:158,”type”:”article”,”title”:”Solarus PVT Hybrid Collector- Test and evaluation of pre-series modules in Moçambique”,”publisher”:”Lund University”,”author”:{“family”:”Bernardo”,”given”:”Ricardo”},{“family”:”Davidsson”,”given”:”Henrik”},{“family”:”Gomes”,”given”:”Joao”},{“family”:”Gentile”,”given”:”Niko”}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 45.

Description of the prototype collector and laboratory set-upAs a part of a project funded by the Swedish International Development Agency (SIDA) and the Gulbenkian foundation of Portugal, a small solar laboratory was constructed. The equipment installed at this laboratory is described in detail in paper XII and summarized below:
1) Data Loggers:
a) Campbell CR1000 DataLogger. Analog, digital and pulse inputs are suitable for the adopted scientific data logger. For the mean voltage input range ±2.5V, maxi-mum resolution is 0.67 mV and measurable through up to 16 single-ended ports. High accuracy, versatility and reliability allowed this product to be spread worldwide for scientific application. The price is approximately 1500 USD.
b) MELACS®. It enables stand alone data logging and remote collection through the built in web server. Connection of multiple loggers (e.g. to increase the number of ports) is possible through the Ethernet port. Voltage input range is fixed to ±3.3V, corresponding to 0.8 mV of resolution and measurable through 8 channels. Pulse and digital channels are also available. It works with open source GPL software. Current price is about 260 USD.

2) Water temperature sensors:
a) PT100 Class A. High precision temperature measurements were carried out through a PT100 sensor with immersed insert. The Class A definition guarantees the accuracy of ?T=±(0.15+0.002·|T|), where |T| is the absolute temperature in °C. Pentronic AB was the chosen manufacturer, which supplied and tested 30 sensors according to EN10204. In order to have similar offset in measurements, the two PT100 with closer response during the test were chosen for the ?T measurements. Despite the benefit of fluid immersed measurement, appropriate plumbing adaptation is required as show in the figure below. Adaptors are rather expensive, approximately 60 USD.
b) LM35CZ. LM35CZ are precision integrated-circuit temperature sensors produced by National Semiconduc-tor Corporation. Voltage output is linearly proportional to Celsius temperature with 0 mV as set point for 0°C and +10.0 mV/°C scale factor; nonlinearity typically below ±1.4°C is guaranteed over the full range of 55-150°C. Accuracy is ±0.4°C, hence ±4 mV, at 25°C, up to a typical value of ±0.8°C in extreme conditions. The price is of approximately 5 USD each. Copper paste on the surface and good insulation around the pipe must be carefully provided to have good thermal contact and low heat losses. Indeed, the sensor could record the air temperature in the proximity of the pipe instead of the pipe surface temperature as shown the figure below. Since the device is not specifically designed for water temperature measurements, it can be successfully used for other applications.

Figure SEQ Figure * ARABIC 44: Sensor positioning for PT100 (left) and LM35 (right)3) Solar radiation:
a) Kipp;Zonen CMP 11. Scientific pyranometer calibrated after purchase according to the technical regulations of World Meteorological Institute. Estimated combined expanded uncertainty for the used device is ±1.4%, corresponding to 8.67 ?V/W/m2 of sensitivity at normal incidence on horizontal pyranometer. Commercial price is about 4,000 USD.

b) Finsun SRS1000. Basic pyranometer with sensing element made of single crystal Si-cell. The output voltage is 100 mV when exposed to 1000 W/m2 solar radiation. Sensitivity, offset and ageing tests were performed. Commercial price is approximately 115 USD.
4) Flow meter.

Kamstrup 10EVL-MP110 energy and flow meter was adopted. No cheaper flow meter was tested.
5) Concentrating thermal (reference) and C-PVT collectors. It is important to mention that this version of the C-PVT solar collector is named V1 in this thesis.

6) Solar tracker. A horizontal single axis tracker (HSAT) was installed. The tracker is based on an engine driven by Melacs® logger. The software controls the position of solar panels using time and location as input. This solution allows a correct positioning without the use of additional photodiodes-based trackers, thus cutting costs and maintenance.

7) IV tracer. The IV tracer used had the capacity to perform IV curves with the limits of 30V and 10A.

The following figures show several aspects of the equipment of the solar lab such as the solar tracker, the two installed collectors, the tank, the pump, the logger, the flowmeter, the MELACS loggers, and more, as well as the set-up for both the longitudinal and transversal IAM measurements:
Figure SEQ Figure * ARABIC 45: The C-T and C-PVT solar collectors installed in the solar tracker (left) and the some of the installation equipment such as computers, CR1000, two MELACS units,flowmeter, expansion valve, pump and tank.Figure SEQ Figure * ARABIC 46: The collectors installed for the transversal IAM measurements (left) and the team celebrating the success of the longitudinal IAM measurements (right)Figure SEQ Figure * ARABIC 47: Detailed view of the C-PVT V1 and the pyranometersThe figure below describes the electrical arrangement of the solar cells PVT V1:
Figure SEQ Figure * ARABIC 48: Electrical diagram of the PVT V1The below shows the areas used to calculate the efficiency of the collector.

Table SEQ Table * ARABIC 10: Different areas used to calculate the efficiency of PVT V1Acells of one receiver (m2) 0.577
Aeffective reflector electrical (m2) 0.869
Effective Concentration Factor (-) 1.506
MethodAs discussed previously in chapter 5.1, there are a number of factors that influence the performance of a C-PVT solar collector. Due to this, performance measurements should be conducted in a specific order. The first step was to determine the efficiency of the solar cells and its relation to the temperature of the working fluid. This test was performed in an incidence angle that maximizes the electrical output, i.e. close to normal incidence, but not normal, due to the asymmetric curvature of the reflector. Once the temperature dependence was determined, the angular dependence or, more accurately, the incidence angle modifier could be measured.

Normally, it is expected that an electric load is permanently connected to the PV cells and electric power is continuously extracted at maximum power point. However, the presented method of instantaneous IV curve measurements simplifies the whole test procedure. These results are less expensive and less time consuming to achieve while still maintaining a good level of accuracy. If an electric load were continuously connected, the absorber would be colder since a part of the incoming radiation would be converted to electricity. This would mean lower temperatures and thus slightly lower thermal losses. This difference is however small and has little impact on the results ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”BMfwJ0G9″,”properties”:{“formattedCitation”:”46″,”plainCitation”:”46″,”noteIndex”:0},”citationItems”:{“id”:160,”uris”:”http://zotero.org/users/4612010/items/W9GNYDVS”,”uri”:”http://zotero.org/users/4612010/items/W9GNYDVS”,”itemData”:{“id”:160,”type”:”article-journal”,”title”:”Performance evaluation of low concentrating photovoltaic/thermal systems: A case study from Sweden”,”container-title”:”Solar Energy”,”page”:”1499-1510″,”volume”:”85″,”issue”:”7″,”source”:”ScienceDirect”,”abstract”:”Some of the main bottlenecks for the development and commercialization of photovoltaic/thermal hybrids are the lack of an internationally recognized standard testing procedure as well as a method to compare different hybrids with each other and with conventional alternatives. A complete methodology to characterize, simulate and evaluate concentrating photovoltaic/thermal hybrids has been proposed and exemplified in a particular case study. By using the suggested testing method, the hybrid parameters were experimentally determined. These were used in a validated simulation model that estimates the hybrid outputs in different geographic locations. Furthermore, the method includes a comparison of the hybrid performance with conventional collectors and photovoltaic modules working side-by-side. The measurements show that the hybrid electrical efficiency is 6.4% while the optical efficiency is 0.45 and the U-value 1.9W/m2°C. These values are poor when compared with the parameters of standard PV modules and flat plate collectors. Also, the beam irradiation incident on a north–south axis tracking surface is 20–40% lower than the global irradiation incident on a fixed surface at optimal tilt. There is margin of improvement for the studied hybrid but this combination makes it difficult for concentrating hybrids to compete with conventional PV modules and flat plate collectors.”,”DOI”:”10.1016/j.solener.2011.04.006″,”ISSN”:”0038-092X”,”shortTitle”:”Performance evaluation of low concentrating photovoltaic/thermal systems”,”journalAbbreviation”:”Solar Energy”,”author”:{“family”:”Bernardo”,”given”:”L. R.”},{“family”:”Perers”,”given”:”B.”},{“family”:”Håkansson”,”given”:”H.”},{“family”:”Karlsson”,”given”:”B.”},”issued”:{“date-parts”:”2011″,7,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 46. Since the cell is encapsulated in silicone, it was not possible to measure the cell temperature directly. Instead, the temperature of the outlet water was measured. In a series connected string, the cell producing the lowest output will be limiting the string output. In general, the warmest cell tends to be the cell with the lowest output, however, this may not always be the case, as there are efficiency differences between each cell due to the production process.

Incidence Angle Modifier testing method:
As mentioned previously, the transverse incidence angle modifier (IAMt) is defined by the reduction in electrical efficiency for a given irradiation caused by the increase of the incidence angle between the sun and the normal to the collector in the transverse direction (?t). This is exemplified in figure below. From 0° to +90° the sun’s direction is inside the acceptance angle of the reflector and outside from 0° to -90°. However, the front part of the receiver accepts light coming in from-90° to 90°. The IAM measurements are a combination of all angular effects such as decrease of transmission in the glazing for high incidence angles and shading effects by edges, etc.

Figure SEQ Figure * ARABIC 49: Transversal incidence angle to the left and longitudinal incidence angle to the rightTo be able to measure IAMt for different transverse angles the longitudinal angle had to be kept equal to zero. This was measured by facing the collector towards the solar azimuth for various tilt angles. This is illustrated below:
/
Figure SEQ Figure * ARABIC 50: Tilting the collector to achieve different transverse incidence anglesThe incidence angle modifier is applied for the direct radiation only. However, even during clear days, there is always a percentage of diffuse light that contributes to the measured power output, and while, in a clear day, this percentage can be around 10%, in less sunny days, this percentage can reach 100%. This way, the diffuse contribution becomes relevant for low concentrating collectors such as this one.

The fraction of useful diffuse radiation for a concentrating collector, relative to the total diffuse radiation on the glazed cover of the collector is described in the figure below. The pyranometer, labelled as (A), will see (1+cos?)2 QUOTE (1+cos?)2 QUOTE (1+cos?)2 of the full sky. This is the same as for the front side of the receiver which is labelled (B). They thus see the same part of the diffuse sky and it would be a correct assumption when a non-concentrating collector is tested. This is however not the case for the backside of the receiver. The acceptance angle for the reflector blocks a substantial part of the sky. This part is indicated with red arrows. The radiation that will reach the backside of the receiver is labelled (C), and is equal to the radiation measured by the pyranometer minus half the sky due to the acceptance angle. This is true for a positive tilt, i.e. the left collector shown in the figure below. The collector on the right hand side of the figure shows the case for tilting the reflector backwards. The pyranometer (D) and the front side (E) of the receiver are unaffected. However, the backside radiation (F) will be half of the sky as long as the tilt ? is less than 90°. This happens since the part outside the acceptance angle is now facing the ground. Thus, the part of the diffuse radiation inside the acceptance angle is always half of the sky.

Figure SEQ Figure * ARABIC 51: Fraction of useful diffuse radiation for different transverse incidence anglesThe fraction, f, of the diffuse radiation that is useful for the collector can be calculated by summing the contributions from the front side and the backside of the receiver and dividing this by the diffuse radiation measured by the diffuse pyranometer. The front side of the receiver accounts for one third of the total glazed area while the backside, via the reflector, accounts for two thirds of the total glazed area. If the collector is rotated as in the left side of the above figure f will be:
f=131+cos?2+23(1+cos?2-12)1+cos?2(eq 1)
If the collector is rotated as in the right side of the above figure f will be:
f=131+cos?2+23(12)1+cos?2 (eq 2)
However, this is true for an infinitely long trough without any shading from the edges. This is not the case for the investigated collector. The front side of the receiver will be only slightly affected by shading and the shading effect is thus omitted. The shading of the backside will be more relevant. This is illustrated to the right in REF _Ref337635252 * MERGEFORMAT Figure 51.

Figure SEQ Figure * ARABIC 52: Shading of the PV cells due to the gables of the collectorThe black arrows hit the edge cells while the red arrows miss the cell. The arrow labelled 1, close to normal incidence will be reflected to the outermost PV cell. So will all rays coming from an even lower angle, e.g. rays labelled 2 and 3. For radiation with a higher incidence angle, the rays will be either reflected to hit another cell or will be stopped by the edges. This means that the outermost cell can only see roughly half of the diffuse sky. The problem is identical for the left side of the collector. This will reduce the contribution from radiation to the backside of the receiver, i.e. (C) and (F) in REF _Ref518880166 * MERGEFORMAT Figure 50 by approximately 50%. This will change equation (1) and equation (2) to:
f=131+cos?2+23(1+cos?2-12)21+cos?2=1+2cos?3(1+cos?)(eq 3) (3)
f=131+cos?2+23(12)21+cos?2=2+cos?3(1+cos?)(eq 4)
Measurements of the IAMt were carried out by varying the tilt ? from -30° to +30° as shown in REF _Ref337634414 * MERGEFORMAT Figure 49 and REF _Ref518880166 * MERGEFORMAT Figure 50. REF _Ref337636397 * MERGEFORMAT Figure 52 shows a plot of equation (3) and equation (4). The variation in the fraction of the useful diffuse radiation is small for this tilt interval. Hence, the fraction of useful diffuse radiation was set to be the average of its value and equal to 50%.

Figure SEQ Figure * ARABIC 53: The fraction of useful diffuse radiation as a function of the collector tiltThe longitudinal incidence angle modifier (IAMl.) was measured while keeping a constant ?t which corresponds to the measured maximum value of IAMt.

ResultsThe figure below shows the measured electrical efficiency per cell area for the V1 PVT collector at 25°C, which is 20.9%. Expressed per active glazed area this efficiency is 13.9%. This means that the maximum electrical power for a collector is 241 W or 139 W/m2 active glazed area. As expected, this number is 11% lower than the optimum output of 269.5 W for a perfect optical efficiency.

The dependence of electrical efficiency on temperature (KT) is -0.41%/K, which in good agreement with values commonly described in literature ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”PiEGGmLV”,”properties”:{“formattedCitation”:”18″,”plainCitation”:”18″,”noteIndex”:0},”citationItems”:{“id”:38,”uris”:”http://zotero.org/users/4612010/items/KYQX6UCB”,”uri”:”http://zotero.org/users/4612010/items/KYQX6UCB”,”itemData”:{“id”:38,”type”:”book”,”title”:”Applied Photovoltaics”,”publisher”:”Routledge”,”publisher-place”:”London ; Sterling, VA”,”number-of-pages”:”330″,”edition”:”2nd edition”,”source”:”Amazon”,”event-place”:”London ; Sterling, VA”,”abstract”:”A reliable, accessible and comprehensive guide for students of photovoltaic applications and renewable energy engineering. This thoroughly considered textbook from a group of leading influential and award-winning authors is brimming with information and is carefully designed to meet the needs of its readers. Along with exercises and references at the end of each chapter, the book features a set of detailed technical appendices that provide essential equations, data sources and standards. Starting from basics with ‘The Characteristics of Sunlight’ the reader is guided step-by-step through semiconductors and p-n junctions; the behaviour of solar cells; cell properties ad design; and PV cell interconnection and module fabrication. The book covers stand-alone photovoltaic systems; specific purpose photovoltaic systems; remote are power supply systems; and grid-connected photovoltaic systems. There is also a section on photovoltaic water pumping system components and design. Applied Photovolatics is well illustrated and readable with an abundance of diagrams and illustrations, and will provide the reader with all the information needed to start working with photovoltaics.”,”ISBN”:”978-1-84407-401-3″,”language”:”English”,”editor”:{“family”:”Wenham”,”given”:”Stuart R.”},{“family”:”Green”,”given”:”Martin A.”},{“family”:”Watt”,”given”:”Muriel E.”},{“family”:”Corkish”,”given”:”Richard”},”issued”:{“date-parts”:”2006″,12,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 18.

Figure SEQ Figure * ARABIC 54: Dependence of the electrical efficiency on temperatureThe next figure shows the electrical transverse and longitudinal incidence angle modifiers for the beam radiation, IAMt in blue and IAMl in red. The measured values are adjusted for temperature variations. The sharp increase/decrease around 0° for the IAMt is due to the radiation shifting from outside to inside of the acceptance angle. The IAMl for the front side and backside receivers is shown in yellow and green respectively. The figure shows that the front side receiver behaves very similarly to a flat plate solar panel. The backside receiver is the main responsible for the efficiency drop during low incidence angles in the longitudinal direction due to the series connection of the cells.

Figure SEQ Figure * ARABIC 55: Electrical transverse incidence angle modifier (IAMt) for beam radiation in blue and the longitudinal incidence angle modifier (IAMl) in red. The IAMl for the backside and the front side of the receiver are shown in yellow and green respectively.By examining the figure, it is possible to conclude that, if the collector was tracking the sun around an axis aligned in the East-West direction, it should maintain the projected solar height over the day close to 10° in order to maximize the annual output. The drop in the longitudinal incidence angle modifier is due to the shading caused by the reflector edges. When 0°<?l<30° the decrease in the IAMl is quite steep. This corresponds to partial shading on the first cell placed at the edge of the backside receiver, as described in the previous chapter. At around ?l=30° the cell on the edge on the backside is totally shaded, eliminating almost completely the production of that string. Shading more cells when ?l>30° will not imply a further production decrease on that string and thus, the total efficiency decrease slows down. Without the diode installed on the string, the drop would be double, since the strings are connected in series. I.e., the total IAM would drop to about 0.5 and not just to the 0.75, as seen in the figure. This is even more obvious, when analysing the backside of the absorber, where the output drops from 0.58 to 0.29, i.e. a 50% reduction. As can be seen from the same figure, the front side is much less affected by the shading. The IAMt shown in figure above is in agreement with previous measurements for the thermal production of a solar thermal collector with the same geometry ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”b7xsIohk”,”properties”:{“formattedCitation”:”47″,”plainCitation”:”47″,”noteIndex”:0},”citationItems”:{“id”:163,”uris”:”http://zotero.org/users/4612010/items/EW8MQU9E”,”uri”:”http://zotero.org/users/4612010/items/EW8MQU9E”,”itemData”:{“id”:163,”type”:”article-journal”,”title”:”Performance Evaluation of a High Solar Fraction CPC-Collector System”,”container-title”:”Journal of Environment and Engineering”,”page”:”680-692″,”volume”:”6″,”issue”:”3″,”source”:”www.jstage.jst.go.jp”,”abstract”:”Japan’s largest platform for academic e-journals: J-STAGE is a full text database for reviewed academic papers published by Japanese societies”,”DOI”:”10.1299/jee.6.680″,”ISSN”:”1880-988X”,”journalAbbreviation”:”JEE”,”language”:”en”,”author”:{“family”:”Bernardo”,”given”:”L. R.”},{“family”:”Davidsson”,”given”:”H.”},{“family”:”Karlsson”,”given”:”B.”},”issued”:{“date-parts”:”2011″}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 47.

The PVT collector is made of two different parts. A front part where the solar cells behave like a standard flat plate solar panel with no concentration and a back part under concentration using a reflector. Since there is no synergic effect from combining non-concentrating solar cells with concentrating solar ones, only one of these alternatives should be the most cost-effective way of building a solar collector rather than a combination of both. The choice between a concentrating or non-concentrating system depends on the concentration factor, the fraction of diffuse to beam irradiation in the geographical location, the compactness needed for the collector, the temperature of the application and many other factors, as discussed in chapter 2.

The reflector part of the collector concentrates the radiation two times on the back side receiver. If the optical efficiency is around 50%, meaning that, under optimum conditions, the collector produces the same electrical output as a flat plate solar panel for the same temperature. This conclusion would change significantly, if the concentration factor were increased and the optical efficiency maintained. Hence, the concentration factor has an important influence on the output per cell area. One way of increasing the concentration could be to reduce the cell area on the backside of the receiver while using a tracking system. This can be done by cutting the cells in half or in thirds in the parallel direction of the busbars. The effect of the radiation profile after reflection should be further investigated.

As shown in REF _Ref520069504 h * MERGEFORMAT Figure 54, a limitation of this study is the reduced amount of measured data for the dependence of efficiency on the temperature. Measurements were also carried out with cheaper sensors in order to verify the possibility of building low investment scientific solar laboratories in developing countries. The overall accuracy of measurement with such sensors was lowered to approximately 9%, but with a cost reduction of above 90% XII.

ConclusionsThe optical properties of PVT V1 were determined. These include the electrical transverse and longitudinal incidence angle modifiers, taking into account edge effects, by-pass diodes, acceptance angle and diffuse radiation contribution. The measured electrical efficiency at 25°C outlet water temperature was 20.9% per cell area and 13.9 % per active glazed area during peak hours. During a large period of the day the output is significantly reduced by the reflector edges, as shown by the IAM measurements. This represents a big margin of improvement for the collector. By removing the cells on the edge, turning the edge cells 90°, dividing the string into three or four parts or even tracking the collector around an axis oriented in the North-South direction, the collector performance can be significantly improved. Hence, the annual production can become competitive with a flat plate solar panel while, at the same time, producing hot water.

Paper II: Testing at Gävle and Darlana University and at SolarusPaper II deals with the measurements on PVT V2, V3 and V4.

It is important to note that the notation of the thesis and paper II are different. In paper two these are called V1, V2 and V3, meaning that V4 in the thesis is V3 in the paper.

Overview on the laboratory set-up for different prototypes testedFor practical reasons, during this paper, the different versions of the PVT collectors were tested in various locations in Sweden at different times, as shown in REF _Ref520074816 h * MERGEFORMAT Table 11, in REF _Ref520074151 h * MERGEFORMAT Figure 56 and in REF _Ref520076672 h * MERGEFORMAT Figure 57. REF _Ref520074816 h * MERGEFORMAT Table 11 also shows the equipment used at each of the locations. All locations have similar latitude and longitude.

Table SEQ Table * ARABIC 11: Overview of measurement locations of paper II
Location Solarus factory in Älvkarleby Darlana University Gävle University
Indoor Outdoor Outdoor Outdoor
IV tracer Same for all measurements
Solar Radiation Reference Cell Reference Cell K&Z CM11 Reference Cell
Temperature recording Not needed LM35 PT100 Not available
Flowmeter Not needed Kamstrup 9EVL-MP115 flowmeter Krohne Optiflux 5000 Not available
Data Acquisition Not needed MELACS National instruments Custom software
Figure SEQ Figure * ARABIC 56: Outdoor measuring for paper II: (a) Solarus Factory PVT V2; (b) Darlana University PVT V3; (c) Gävle University PVT V4Indoor testing at the Solarus LaboratoryThe indoor solar simulator consists of two rows of eight 1000W halogen light bulbs. The indoor solar laboratory was used for testing the shading impact on the strings using the Solarus custom-size cells. As in many solar simulators, the light distribution is a drawback, since it is does not matching perfectly with the sun. The indoor solar laboratory was used for testing the shading impact on the strings using the Solarus cell size.

Figure SEQ Figure * ARABIC 57: The solar simulator for the indoor measurementsOutdoor TestingThe Outdoor Solarus laboratory are shown in REF _Ref520077561 h * MERGEFORMAT Figure 56.

The IV Tracer is a custom made device, interfacing with the COM interface. A custom Excel macro logs the data periodically or on demand. The IV Tracer uses a current generator to measure the performance; it ramps up the current from zero to maximum, taking voltage and current samples in the process which lasts less than a second. Each IV curve, with values of Imp, Isc, Vmp, Voc, Pmax, FF is saved as a separate CSV file. The device was found to have a resolution of 0.008V and 0.002A, just like in chapter 5.3 and 5.2. This IV tracer is used throughout this thesis.
The reference cell is from the European Standard Testing Institute and is calibrated to be linear from zero to 28.7mV at 1000W/m². This reference cell had two outputs: one for data and one for temperature correction. The CM6 in Dalarna measured hemispherical irradiation with a total accuracy of 2% of the measured value. The CM11 measured diffuse irradiation and has an accuracy of ±1%.

LM35 temperature sensors were used for measuring the inlet and outlet temperatures in Älvkarleby, with a measurement range of -55°C to +150°C and accuracy 0.5°C at 25°C. These were placed against the copper pipe on the outside of the collector with copper paste being used to ensure a good thermal connection. In Darlana, the sensors used were PT100s inserted inside the pipe, for water temperature, and in the shade for ambient temperature. These sensors have an accuracy of ±0.3°C at 0°C. In Alvkarleby, the MELACS was used to log data. The MELACS (Micro Energy Logger And Control System) is a device built around a PIC16F micro controller. It was used as a standalone data logger to read data from thermal sensors and the reference cell. It accepts eight analogue voltage inputs in the range +/- 3.3V with a resolution of 0.8mV. In Dalarna, data was logged via a National Instruments Data Acquisition Unit using LabView. A Kamstrup 9EVL-MP115 flowmeter was used in Älvkarleby, which sends 5760 pulses per litre flow, with precision varying from ±1.5% at 2°C to ±0.5% at 120°C. The Dalarna setup had Optiflux 5000 flowmeters from Krohne, which were accurate to ±0.1% of the measured value.

Measured CollectorsSolarus is committed to continuous development and as such as produced a large number of collectors prototypes for research. Differences between the tested PVT versions are shown in the table below. It is important to bear in mind that the thesis names of different collector versions are not the same as the names in paper II.

Table SEQ Table * ARABIC 13: Differences between the tested PVT versionsVersion PVT V2 PVT V3 PVT V4
Collector Box Earlier version Improved version Improved version
Receiver Type Non-Massive Aluminium core Massive Aluminium core Massive Aluminium core
End Gables Reflective Transparent Transparent
Cell Size All cells were 1/6 of the size of a standard cells All cells were 1/6 of the size of a standard cells One trough with cell strings of 1/3, and the other trough with 1/6
Collector Box: The collector box has been improved from PVT V2 to PVT V3. The new collector box is sturdier and has improved water insulation.
Receiver Type: The receiver design has been improved from PVT V2 to PVT V3. The V2 consisted of a number of parallel pipes of about 5mm diameter, laminated with two thin sheets of metal on either side, while V2 is a massive aluminium extrusion a patented cross-section. This receiver should be more effective at cooling the solar cells, thus producing a very even heat distribution which in turn reduces the F’ value.

End Gable: The end gable makes part of the box structure and its transmittance (or reflectance) properties are important for the collector performance.

Cell Size: PVT V4 was specially built to evaluate the difference between collectors using standard cells cut into 1/3 and 1/6 of the original size. Strings with these types of cells were expected have different power performances over the day.

With emphasis on minimizing the impact of the longitudinal shading, the PVT collector were constructed and tested. The main differences relevant to this study are described below.

Figure SEQ Figure * ARABIC 58: Differences between PVT V2 and PVT V3ResultsIndoor Testing:
The figure below shows the power reduction as well as the behavior of Vmp, Voc, Imp and Isc during shading and that the shading greatly influences the intensity (A) but not the Voltage (V). Three types of shading were tested: whole string and single cell (parallel or perpendicular to the cell busbar). It is important to notice that the percentage of shading applied the cell or string is not exact.
Figure SEQ Figure * ARABIC 59: (a) Power Reduction; (b) Shading impact on FF; (c) Shading impact on Voc & Vmp; (d) Shading impact on Isc & Imp
Outdoor Testing:
PVT V2 was tested in Älvkarleby at Solarus on the 1st of April while V3 at Darlana University on the 16th of May. REF _Ref520082136 h Figure 60 shows the electrical power output of one trough (both front and reflector sides of the receiver) for both V2 and V3 over stable sunny days. The collector tilt was selected to maximize output for the location and the time of the year in which the measurements took place. Cell temperature is assumed to be the same as the water temperature which, during the day, varied between 10 and 20ºC for V2 and 20 and 40ºC for V3.

REF _Ref520082136 h Figure 60 shows sharp increases and decreases of electrical power output for both PVT V1 and V2 due to the reflector side of the receiver having one string (out of the two strings) not working. Since the cells are connected in series, as soon as the first cell becomes shaded, the power of the whole string is reduced. Unshaded power production occurs only for little over 1h for V2 while in V3, it lasts for over 2h00 which is double of the duration. This is because V2 was an early prototype, so the cells strings were longer, causing the shading to begin earlier when compared to V3. The cell strings were longer because the spaces between each cell were larger (cell number is maintained). The peak power of V2 is 117W (for one through) while V3 shows 89W (for one through). This difference is mainly justified by the difference in cell operating temperature and by the reflectance of snow in front of the collector. The findings for V2 match the results build on the work of paper VII, made on a similar PVT prototype.

Figure SEQ Figure * ARABIC 60: Electrical Power measured in a) PVT V2 measured in Älvkarleby (left); b) PVT V2 at Darlana University (right)The power profile marked as “interesting feature” was seen to b caused by the combination of the movement of the shade caused by the aluminium frame and the shade caused by the end of the reflector. This was not visible in the figure above since V2 has reflective end gables, while V3 has transparent end gables.

639445887730A
B
00A
B
Figure SEQ Figure * ARABIC 61: Effect of the shading of the aluminium frame on a PVT with: (a) reflective end gables; (b) transparent end gables;This effect is further described in the figures above, which shows how the shading caused by the aluminum frame varies over the day. The arrows show the movement of the shade produced by the frame on both the reflector trough and the reflector underside, as the sun moves from horizon to zenith. This evaluation is coherent with previous research ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”ZSz4T3H2″,”properties”:{“formattedCitation”:”47″,”plainCitation”:”47″,”noteIndex”:0},”citationItems”:{“id”:163,”uris”:”http://zotero.org/users/4612010/items/EW8MQU9E”,”uri”:”http://zotero.org/users/4612010/items/EW8MQU9E”,”itemData”:{“id”:163,”type”:”article-journal”,”title”:”Performance Evaluation of a High Solar Fraction CPC-Collector System”,”container-title”:”Journal of Environment and Engineering”,”page”:”680-692″,”volume”:”6″,”issue”:”3″,”source”:”www.jstage.jst.go.jp”,”abstract”:”Japan’s largest platform for academic e-journals: J-STAGE is a full text database for reviewed academic papers published by Japanese societies”,”DOI”:”10.1299/jee.6.680″,”ISSN”:”1880-988X”,”journalAbbreviation”:”JEE”,”language”:”en”,”author”:{“family”:”Bernardo”,”given”:”L. R.”},{“family”:”Davidsson”,”given”:”H.”},{“family”:”Karlsson”,”given”:”B.”},”issued”:{“date-parts”:”2011″}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 47 and paper VI.

Figure SEQ Figure * ARABIC 62: (a) Electrical power output comparison between two versions with transparent and reflective end gables; (b) Electrical power output from the back side of the receiver PVT V4 (with 1/3 solar cells) measured at Gävle University on the 15th of July;After full day of testing, the PVT V3 was modified and the transparent end gables were replaced by a reflective. The collector was then tested again in the next day which was also a stable sunny day. This way, all collector properties were exactly the same and the only difference that is measured is the effect of the end gable being transparent or reflective. For comparative purposes, the power output of V3 with reflective end gables was normalized to the solar irradiation of the day of test in the V3 with transparent gables. This is shown in REF _Ref520083334 h * MERGEFORMAT Figure 62A.

REF _Ref520083334 h * MERGEFORMAT Figure 62B shows the power from the reflector side of the experimental trough in the PVT V4. This trough contains strings with cells 1/3 of the standard size and was tested at Gävle University with perfectly stable solar conditions. Since, at this time, there were still no means to control the collector temperature at this location, the collector was kept fairly constant at stagnation (around 120ºC when the pipes allow air to circulate through the receiver). The time duration of no shading on the reflector side was seen to be considerably longer than in V2 and V3, lasting more than 3h30. This happens because the strings with cells of 1/3 the standard size are shorter, since these strings have only half of the number of spaces between the cells.

Furthermore, also for V4, the “interesting feature” is again seen due to the combination of the shading caused by the aluminium frame and the end of the reflector. These measurements were tested twice for confirmation.

REF _Ref520083796 h Figure 63A shows the power on the lower side of both troughs of the PVT V4 on a day with perfect and stable solar conditions and collector temperature maintained at stagnation.

Figure 63: (a) Power output comparison between two V2s with 1/3 and 1/6 cell sizes (left); (b) Picture of PVT V3 showing a band of shading for the troughs with different cell sizes of V4 (right)
At (0,0) on the REF _Ref520083796 h Figure 63A, two electrical power readings were taken when neither of the troughs had any shading, but just before the shading commenced; Point (0,0) in the figure is not when the sun is normal to the collector. The collector was rotated about 3º relative to the sun in order to provoke shading. For each angle, the two power readings were taken almost simultaneously from both troughs. The figure shows that when there is no shading, the trough with smaller cells produces slightly more power, but the longitudinal shading also starts much before, which is a much more relevant effect for the annual output. The trough with larger cells produces more power even under shading since a larger part of the cell remains unshaded, as seen in REF _Ref520083796 h Figure 63B, which roughly corresponds to a 15º angle in REF _Ref520083796 h Figure 63A.

ConclusionsThe indoor solar laboratory tests showed that shading a cell parallel or perpendicular to the cell busbar had a similar impact in terms of power reduction. When 25% and 50% are covered, the power decrease is larger for the whole string than for a single cell shaded. The whole string experiences a power decrease close to the percentage of the area that is shaded while a single cell has a smaller decrease in power. Interestingly, having 75% of the whole string shaded or 75% of one solar cell resulted in a similar decrease in power. As expected, shading one whole cell or string yields a very similar result, with the power output very close to 0. The FF was observed to increase, as the shading increased from 0% to 75%.

For the latest PVT version, at 25ºC and 1000W/m2, the collector efficiency was found to be 13,7% yielding 237W. The efficiency per cell area was found to be 20,3 %. At peak sun, the reflector side of the receiver produced 58% of the total power in accordance with measurements done by the author in paper VII.

The testing on the three PVT versions showed clearly that the longitudinal shading caused by the frame represents a window of opportunity for the improvement of this PVT design, in terms of power production optimization. The results also show clearly that the string length has a significant impact on the duration of peak power with V2 having 1h, V3 having 2h and V4 having more than 3h30. The study shows that using cells with 1/3 the standard size gives better performance than smaller cells. Although larger cells show decrease in power production of 4% during peak power, peak power also lasts for a considerably longer period. Overall the net result will be a gain in power production over the day. Larger cells will also reduce the production costs by halving much of the work required. Further work includes investigating the extent of the benefits of using different cell types and sizes. Using cell strings with cells that are half the standard size and have four busbars instead of three is an option that should be evaluated. The additional busbars increase the efficiency of the cell by reducing the resistivity losses ADDIN ZOTERO_ITEM CSL_CITATION {“citationID”:”eNgmExXf”,”properties”:{“formattedCitation”:”18″,”plainCitation”:”18″,”noteIndex”:0},”citationItems”:{“id”:38,”uris”:”http://zotero.org/users/4612010/items/KYQX6UCB”,”uri”:”http://zotero.org/users/4612010/items/KYQX6UCB”,”itemData”:{“id”:38,”type”:”book”,”title”:”Applied Photovoltaics”,”publisher”:”Routledge”,”publisher-place”:”London ; Sterling, VA”,”number-of-pages”:”330″,”edition”:”2nd edition”,”source”:”Amazon”,”event-place”:”London ; Sterling, VA”,”abstract”:”A reliable, accessible and comprehensive guide for students of photovoltaic applications and renewable energy engineering. This thoroughly considered textbook from a group of leading influential and award-winning authors is brimming with information and is carefully designed to meet the needs of its readers. Along with exercises and references at the end of each chapter, the book features a set of detailed technical appendices that provide essential equations, data sources and standards. Starting from basics with ‘The Characteristics of Sunlight’ the reader is guided step-by-step through semiconductors and p-n junctions; the behaviour of solar cells; cell properties ad design; and PV cell interconnection and module fabrication. The book covers stand-alone photovoltaic systems; specific purpose photovoltaic systems; remote are power supply systems; and grid-connected photovoltaic systems. There is also a section on photovoltaic water pumping system components and design. Applied Photovolatics is well illustrated and readable with an abundance of diagrams and illustrations, and will provide the reader with all the information needed to start working with photovoltaics.”,”ISBN”:”978-1-84407-401-3″,”language”:”English”,”editor”:{“family”:”Wenham”,”given”:”Stuart R.”},{“family”:”Green”,”given”:”Martin A.”},{“family”:”Watt”,”given”:”Muriel E.”},{“family”:”Corkish”,”given”:”Richard”},”issued”:{“date-parts”:”2006″,12,1}}},”schema”:”https://github.com/citation-style-language/schema/raw/master/csl-citation.json”} 18.

To minimize the effects of longitudinal shading, it is recommend building the PVT collector with a transparent or much thinner frame. Reducing the frame shadow by half is expected to make a significant difference. Other measures like having less cells per string should also be evaluated. Alternatively, other reflectors geometries for the presented PVT concept can also be studied.

The receiver holder also creates a shade that is visible in the reflector. It is likely that this effect is not significant but this should be further investigated, as it can further increase the output of the PVT.

Although previous tests have unequivocally shown that transparent end gables perform better at large incidence angle than opaque, the results show no clear difference between having transparent or reflective end gable in the PVT, which is unexpected. The difference however may within the measurement error. More testing is required for the larger incidence angles. If using larger cells, the transparent end gables collector should perform better.

Testing at Gävle UniversitySolar Laboratory at the University of GävleAn outdoor test rig laboratory was built at University of Gävle (HiG) by the author with the help of master students. The site is located at latitude: 60° 40′ 1.1892″ North and longitude: 17° 6′ 57.4524″ East.Solar Thermal Test Equipment
The thermal rig circulation system was developed for thermal collector testing by a company named Finsun Inresol AB. The goal of this system is to regulate the temperature and flow of water to the thermal collectors in order to allow measuring solar collectors.

This system has the following components: a control unit (MELACS), feed water pump, flow meter, mixing tank, heating apparatus, expansion tank, automatic ?ow control valve, LM35 temperature sensors, and a plate heat exchanger as illustrated in the figure below.

Figure 64: Schematic drawing of the test rig (Source: Finsun AB)The system features two independent thermal circuits: a closed one, with insulation, that feeds the thermal collectors that is to be tests and an open one with grid water that is used for cooling the closed circuit. The system uses two circulation pumps for transport of heat.

Two P.I.D algorithms, one for cooling water valve control and one for heater intensity were created to maintain the desired system temperature. The MELACS (Micro Energy Logger And Control System) unit controls the thermal rig. Four temperature sensors LM35 from Texas Instruments are placed on the test rig as shown in figure above. They are only used for control of the rig. According to Texas Instruments, these sensors measure temperatures between -55°C and 150°C with an accuracy of 0.5°C at 25°C.

The expansion tank is used to protect the closed circuit from pressure above 1.5 bars. To simplify the analysis of the measurement results whenever the weather conditions allowed, the heat-transfer fluid used has been water.

This system was later adapted to test the Solarus concentrating PVT solar collector. Together with a company called Insitu AB several changes were made:
The flow to the collectors was divided into two so that two collectors (or troughs) could be tested simultaneously; New and more accurate flowmeters were installed (insert brand) in both collector inlets; A scientific logger (CR1000 from Campbell Scientific) was installed to record all measurements as well as programmed to control the timing of the measurements; Temperature sensors (PT100 from Pentronic) were installed. Four of them measured the inlet and outlet water temperature of the collector, while the fifth measured the ambient temperature. They have an accuracy of ±0.15°C at 0°C. CITATION Pen l 1036 (Pentronic, s.d.)In addition, it is important to say that all sensors were calibrated by the company In Situ Instrument AB, before the testing period started.

Solar Electrical Test Equipment
The IV Tracer uses a current generator to measure the performance; it ramps up the current from zero to maximum, voltage and current samples are taken during the process, which lasts less than a second. It interfaces with a computer via the USB cable, and an Excel macro sheet logs data. The device has a resolution of 0,008V and 0,002A.

Solar Radiation Equipment
Two pyranometers are used from Kipp;Zonen: one for the global irradiance (CMP6) and one for the diffuse irradiance (CMP3). To measure the diffuse irradiance, the pyranometers is combined with a shadow ring reclining. Both pyranometers are mounted in the plane of the collector. The level is initially adjusted thanks to the feet of the devices parallel to the ground.

Rotating Stand
Insert description
Measured Thermal and Electrical ParametersThermal Parameters
The most important parameter of a solar thermal collector is the efficiency curve which is defined by peak efficiency and the heat loss coefficient of first and second order. Other values like the diffuse efficiency are also important.

A thermal efficiency curve is measured by taking several thermal efficiency points at different temperatures (examples TCollector = 25°C, 40°C and 60°C) and extrapolating the curve to peak efficiency and stagnation temperature. This way, we have used the steady state method instead of quasi dynamic testing method. All thermal data was taken at a constant irradiation that was superior to 800W/m2.

Table 5.1 describes the parameters were measured during the testing period, the logging and measuring equipment and the time interval between two measurements.
Table SEQ Table * ARABIC 12: Measured parameters for testing the electrical and thermal part of the PVT collectorParameter Equipment Unit Comments
Imp, Isc, Vmp, Voc, Pmp CR1000
IV tracer A, V, W Instantaneous electrical measurements is made by performing four different IV curves every 30 seconds.

Tin, Tout CR1000
PT100 °C
Inlet and outlet temperature of the collector.

Measured every 7.5 seconds. Two pairs of measurements, one for each trough.

Ta CR1000
PT100 °C
Ambient temperature.

Measured every 7.5 seconds.

IG CR1000
CMP6 W/m2
Global irradiance.

Measured every 7.5 seconds.

ID CR1000
CMP3 W/m2
Diffuse irradiance.

Measured every even 7.5 seconds.

Pyranometer with shadow ring.

V1, V2CR1000
Flow meters l/min
Water flow to each trough of the solar collector.

Measured every 7.5 seconds.

The average temperature of the collector is given by the formula:
Tcollector = (Tin +Tout) / 2
Pthermal = M.Cp.?T.Area,
Efficiency =
Some additional parameters must be referred:
M, Mass
Cp, Specific heat capacity of water, Joules/Kg.?
Area, useful area of the collector
Prototype Collectors testedThree prototypes C-PVT solar collectors were constructed. These collectors were made with different top and bottom receivers to increase the number of tests that could be performed. All prototypes had identical collector boxes. The receivers were also identical with the exception of 5 parameters that were varied: Strings number, cell size, fabrication method, bottom silicone layer and type of silicone cells. The table below shows the main characteristics of these prototypes:
Table SEQ Table * ARABIC 14: Characteristics of the receivers of the prototypesName Trough Strings number (number of cells) Cell Size Fabrication Bottom Silicone Layer Cell Type
Prototype 1 Top 2 (38-38) 1/6 Hand-made Red Silicone Polycrystalline
Bottom 2 (19-19) 1/3 Hand-made Red Silicone Polycrystalline
Prototype 2 Top 2 (19-19) 1/3 Hand-made Red Silicone Polycrystalline
Bottom 4 (4-15-15-4) 1/3 Hand-made Red Silicone Polycrystalline
Prototype 3 Top 4 (4-15-15-4) 1/3 Machine-made Transparent Silicone Polycrystalline
Bottom 4 (5-14-14-5) 1/3 Machine-made Transparent Silicone Monocrystalline
The receivers of the prototypes had two or four strings with different numbers of solar cells. Two cell sizes were used: 1/3 (52*148mm) and 1/6 (28*148mm). The fabrication process of the solar cell strings was either hand-made or machine-made. The manual soldering process was expected to create considerably more micro-cracks in the cells. All receivers sides had 18,2% efficiency polycrystalline cells from the Lithuanian cell manufacturer Solimpeks with the exception of one receiver side that was composed of monocrystalline Taiwanese cells which provided by AKW cells with 19,3%. Each cell string possessed one bypass diode to mitigate shading issues.

Figure 3 shows Prototype 1 that was used to compare the performance of receivers with one third cells and one sixth cells. Both receivers are fully identical with the exception of the cell size. Cell area is the same on both receivers.

Figure 3 – Prototype 1
Prototype 2, shown in figure 4, was constructed to compare the performance of receivers with two and four strings. The receivers are fully identical with the exception of the number of strings and the number of bypass diodes.

Figure 4 –Prototype 2
Prototype 3 is the only machine-made receiver. The top receiver is composed by four cell strings: two of which have 4 cells and the two with 15 cells, just like the bottom receiver of prototype 2. The bottom receiver also has four strings but two strings of 5 cells and the two others with 14 cells. The cells in the top are polycrystalline while bottom are monocrystalline. Unlike prototype 1 and 2, cell encapsulation is made only with transparent silicone layers, as it is noticeable in Figure 5.

Figure 5 –Prototype 3
Initial electrical and thermal tests at HiGGävle University Testing (paper X) Prototype 1 compares one third cells and one sixth cells. IV curves were measured at HiG and the parameters are shown in the table below. These values were measured on the 4th of August at 11:05, the solar irradiation was 921 W/m2 and the ambient temperature was 21,9°C.

As expected, the backsides produce more power due to the concentration. The backside of the trough with 1/3 cells had some micro-cracks due to the hand-soldering of the cells in the receivers and thus presents a lower output than expected.
  Top trough (1/6) Bottom trough (1/3)
Topside Backside Topside Backside
Pmax (W) 37,3 47,3 37,6 39,42
Imp (A) 2,0 2,7 4,1 4,2
Isc (A) 2,1 3,1 4,4 4,3
Voc (V) 21,8 22 11,1 11,1
Vmp (V) 18,6 17,51 9,1 9,4
FF (%) 81,5 68,7 77,2 81,9
Electrical efficiency (%) 13,8 17,6 14 14,6
Tin (°C) 39,3 39,3 39,6 39,6
Tout (°C) 41,9 41,8 41,8 41,8
Table 2-Electrical measurements at HiG for prototype 1.

The simulator is a flash light simulating an irradiation of 1800W/m². In the simulator, only the receivers are tested. Thus the backside the backside has a similar efficiency to the topside in Table 3.

  Top trough (1/6) Bottom trough (1/3)
Topside Backside Topside Backside
Pmax (W) 87,6 83,7 83,7 87,05
Imp (A) 3,95 3,77 3,77 8,03
Isc (A) 4,13 3,97 3,97 8,25
Voc (V) 24,65 24,57 24,57 12,38
Vmp (V) 22,20 22,18 22,18 10,85
FF (%) 86,12 85,74 85,74 85,24
Electrical efficiency (%) 16,8 16,1 16,1 16,5
Table 3 – Electrical efficiency with Solarus simulator for prototype 1.

These efficiencies are questionable. Cell Area in a receiver = 52*148mm * 38 cells = 0.29 m2 Probably the solar simulator was giving 2000W/m2 instead of 18000.

The electroluminescence test on the same prototype shows the following results:
Figure 7 – a) Top trough topside 1/6; b) Top trough backside 1/6;
c) Bottom trough topside 1/3; d) Bottom trough backside 1/3
The electroluminescence pictures clearly show micro-cracks in the cells which affects the cell output. This happens due to the fact that the cells were hand-soldered.

Prototype 2 compares troughs with two strings and four strings. IV curves were taken at HiG. The test was carried out on the 13th of August at 12:30, the solar irradiation was 968 W/m2 and the ambient temperature was 17,8°C.
  Top trough (2S) Bottom trough (4S)
Topside Backside Topside Backside
Pmax (W) 35 45,5 36,3 46,7
Imp (A) 4,0 5,2 2,0 2,7
Isc (A) 4,3 5,5 2,5 3,3
Voc (V) 10,6 10,9 21,7 21,2
Vmp (V) 8,8 8,8 18,2 17,6
FF (%) 76,7 76,2 67,3 65,8
Electrical efficiency (%) 12,3 16,1 12,8 16,5
Tin (°C) 48 48,1 48 48
Tout (°C) 49 48,6 48,8 48,9
Table 4-Electrical measurements at HiG for prototype 2
Again the backside performs better than the topside due to the concentration. Also as expected, there is no significant power difference between 2 or 4 strings at peak sun. The difference should only be shown when there is shading.
The simulator gave the following results:
  Top trough (2S) Bottom trough (4S)
Topside Backside Topside Backside
Pmax (W) 87,42 86,25 82,71 82,36
Imp (A) 7,97 8,15 4,34 3,69
Isc (A) 8,31 8,42 6,16 6,07
Voc (V) 12,4 12,11 24,23 24,73
Vmp (V) 10,97 10,58 19,08 22,35
FF (%) 84,88 84,61 55,38 54,91
Electrical efficiency (%) 16,6 16,4 15,7 15,6
Table 5-Electrical efficiency with Solarus simulator for prototype 2
Just like in prototype 1, it seems that some micro-cracks appear due to the hand-made production.

The electroluminescence test on prototype 2 shows the results in Figure 8.

Fig. 8 – a) Top trough topside 2S; b) Top trough backside 2S; c) Bottom trough topside 4S; d) Bottom trough backside 4S
Prototype 3 is the only machine-made receiver. IV Curves were taken on the 14th of August at 12:06, the solar irradiation was 964 W/m2 and the ambient temperature was 22,1°C.
  Top trough (poly) Bottom trough (mono)
Topside Backside Topside Backside
Pmax (W) 44,2 53,4 40,1 53,7
Imp (A) 2,4 3 2,2 3,1
Isc (A) 2,5 3,3 2,4 3,4
Voc (V) 22,9 22,8 22,3 22,2
Vmp (V) 18,5 18 18,3 17,4
FF (%) 75,9 72 75,8 71,9
Electrical efficiency (%) 15,6 19 14,2 19
Tin (°C) 31,6 31,6 31,7 31,7
Tout (°C) 33,6 33,5 33,4 33,5
Table 6-Electrical measurements at HiG for prototype 3.

These results also underline the difference between the topsides but not between the backsides. The topside of the top trough composed with 4 strings (4 – 15 – 15 – 4) of polycrystalline cells is more electrically efficient than the topside of the bottom trough which contains 4 strings (5 – 14 – 14 – 5) of monocrystalline cells. Those results are not expected since monocrystalline cells are supposed to be more efficient than polycrystalline cells. This is not what the measurements show because the monocrystalline cells used there were already damaged. Maybe it is accentuated by the disposition of the cells, they are in four strings but the number of cells per string is different.
When the three prototypes are compared together, such as in Table 7, the best electrical efficiency panel is the machine-made one, it always gives more power. This conclusion is not surprising, since for hand-made prototypes cells are soldered manually which means that some micro-cracks arise from prototype production issues that do not occur in automatic cell soldering production with the machine-made prototype.
Table 7-Electrical efficiency comparison measured at HiG for prototype 2, 3 and 1.

The last test carried out is plotting longitudinal and transversal IAM for topsides and backsides of both prototype 2 (handmade, 4S vs 2S) and prototype 3 (Italian machine-made, polycrystalline vs monocrystalline).
0-635Fig. 9 – On topside, longitudinal IAM comparison between handmade 4S-2S (prototype 2) vs Italian machine-made (prototype 3)
Fig. 9 – On topside, longitudinal IAM comparison between handmade 4S-2S (prototype 2) vs Italian machine-made (prototype 3)
Fig. 9 – On topside, longitudinal IAM comparison between handmade 4S-2S (prototype 2) vs Italian machine-made (prototype 3)
Fig. 9 – On topside, longitudinal IAM comparison between handmade 4S-2S (prototype 2) vs Italian machine-made (prototype 3)

left3526790Fig. 10 – On backside, longitudinal IAM comparison between handmade 4S-2S (prototype 2) vs Italian machine-made (prototype 3)
Fig. 10 – On backside, longitudinal IAM comparison between handmade 4S-2S (prototype 2) vs Italian machine-made (prototype 3)
Fig. 10 – On backside, longitudinal IAM comparison between handmade 4S-2S (prototype 2) vs Italian machine-made (prototype 3)
Fig. 10 – On backside, longitudinal IAM comparison between handmade 4S-2S (prototype 2) vs Italian machine-made (prototype 3)

Fig. 11 – On topside, transversal IAM comparison between handmade 4S-2S (prototype 2) vs Italian machine-made (prototype 3)
left3529330Fig. 12 – On backside, transversal IAM comparison between handmade 4S-2S (prototype 2) vs Italian machine-made (prototype 3)
Fig. 12 – On backside, transversal IAM comparison between handmade 4S-2S (prototype 2) vs Italian machine-made (prototype 3)
Fig. 12 – On backside, transversal IAM comparison between handmade 4S-2S (prototype 2) vs Italian machine-made (prototype 3)
Fig. 12 – On backside, transversal IAM comparison between handmade 4S-2S (prototype 2) vs Italian machine-made (prototype 3)

The topsides on each trough are less impacted by a change of angle than the backsides, since the longitudinal and transversal IAM stay close to 1 even by tilting the collector. While longitudinal and transversal IAM change a lot on backsides. The tilt influences the performances of cells on the backside, the reflection on these cells depends on the tilt.

The power was relatively stable during the measurements. Figure 13 and 14 notices the power normalized to 25°C and 1000W/m2 during six days.

Fig. 13 – Power normalized for the topside of the top trough
Reliability of power given by the panel
The electrical power of each of the 4 receiver sides was tracked during one week.

The variation found was considered to be within the measurement error. The power remains at the same level, even after being taken to high temperatures. This indicates that the cell encapsulation in the Italian receiver is sufficient to cope with the contract and expansion.

The second axis should say “Percentage of the decrease”.

The line seems strange. Is it connected to the blue dots in anyway?
Which point is the 100%? It should be the average.

Fig. 14 – Power normalized for the backside of the bottom trough

Daily Thermal Power for the Italian panel
Zoom up of the daily electrical power
ConclusionEfficiency CurveRayTracing with TonatiuhMethodTonatiuh and MatlabThe Monte Carlo method uses the principles of geometrical optics as a statistical method to get a complete and statistically viable analysis of an optical system. Several different Monte Carlo ray tracer software exist and they are powerful tools in the design and analysis of solar concentrating systems. This thesis uses mainly Tonatiuh software although the author has also conducted some simulations in Soltrace in paper XVIII.
Tonatiuh is an open-source software especially developed for optical simulation of solar concentrating systems. The program generates rays that simulate the sun and calculate the intersections of these rays with system surfaces. The sun light is defined by the sun position, i.e. the elevation and the azimuth. These two parameters can also be calculated as a function of the day, the hour, the latitude and the longitude.
The main advantage of Tonatiuh resides in the possibility to write a script for parametrical simulations. This script allows launching several simulations and saving the results. With a script, it is possible to simulate an entire year by using a loops in the script. A disadvantage of Tonatiuh is not having the possibility to conduct post-processing analysis of the results. In this way, in order to extract the data Matlab was used to allow sorting and analyzing large amount of values rapidly since once a simulation is done the Tonatiuh software exports the results either as binary file (.dat) or as SqL database file (.sql).
Each simulation consists of 10,000 solar rays that are sent in the direction of the collector and whose intersection points are calculated, in order to obtain the total power from the photons that is reaching each side of the receiver. For each annual simulation, the power is calculated at each hour (i.e. in total 24 simulations per day, 8760 simulations per year) with an accuracy of 10,000 rays.
The sun shape follows a pillbox distribution, i.e. the solar intensity is the same on each point of the sun’s disk, as shown in the figure on the left. The parameter of this flat distribution is the half-angle width of 4.65mrad. Additionally, the irradiance is always set at 1,000 W/m² and the weather is not considered. Simulations were made for the latitude and longitude of Gävle in Sweden (60,674°N, 17,142°E) and at the equator (0,000°N, 17,142°E).

Figure SEQ Figure * ARABIC 65: Illustration of the pillbox sun shapeOptical propertiesThe simulated solar collector uses reflector material made of anodized aluminum with a total solar reflectance of 95% (measured according to norm ASTM891-87) according Alanod, 2013. The glass cover of the collector is made of low iron glass with solar transmittance of 95% at normal incidence angle and a refractive index of 1.52 (measured according to the norm ISO9050 for solar thermal), according SunArc 2013. The solar transmittance of the plastic gables is 91% and its refractive index is 1.492. Each material has been defined with a slope error of 2mrad to account for macroscopic defects. It was assumed that the light reaching the receivers is fully absorbed.

Software limitations
Regarding the software used for the sets of simulations, some limitations were found:
Tonatiuh simulates the apparent movement of the “sun” around the collector as a full 360° in longitudinal directions over a day. This meant that we had to set a time for sunrise and sunset, in order to avoid having output during the night. The exact time of the sunset and sunrise differs throughout the year and in the different locations. Since Tonatiuh is only able to store 24 values (1 per hour), it was necessary to set the sunset and the sunrise by hours instead of by minute, which lead to a slight inaccuracy. However, this error is not significant since the energy output at low angles is significantly lower when compared with the values at midday and since the time period is never longer than 30 minutes.

No meteorological data has been inserted in the ray tracing simulation tool. Some climates have over 50% diffuse radiation which considerably changes the results. Currently the simulations are conducted for one fully sunny year.
IAM
Incidence Angle Modifier (IAM) is the variance in output performance of a solar collector as the angle of the sun changes in relation to the surface of the collector. The longitudinal and transversal IAM can be obtained through the overall and optical efficiency, and aperture area (Aptarea). These values were collected from a Matlab script. The aperture area for receiver side is given by the following Equation 2.1.

Aptarea= z × 4 × f – thicknesssreceiver2× Lengthreceiver (eq. 2.1)
The aperture area allows the calculation of the overall efficiency of the collector ADDIN RW.CITE{{43 WilliamBStine 2009}}4.

Eff(?i) = Power ?i WIa W/m² × Aptarea m²(eq. 2.2)
Where the Power ?i is given by Tonatiuh and Ia is the solar irradiance that passes through the collector aperture, with a value of 1 000 W/m².

The optical efficiency (?opt) is given by the maximum value of Equation 2.3.

?opt = max(Eff(?i))(eq. 2.3)
With all the parameters obtained, the transversal and longitudinal IAM is obtained using Equation 2.4.

IAM(?i) = Eff (?i)cos?i × ?opt(eq. 2.4)
Where ?i are the angles -90°, -89°, -88°, -87°, -86°, 85°, .. 0 .. , 85°, 86°, 87°, 88°, 89°, 90°. The interval between angles was set in order to achieve a more accurate data.

ResultConclusionString Layout with LT SpiceMethodResultConclusion
Overall ConclusionsThe simulated raytracing profile is consistent with the measured IAM profiles during collector testing.

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