1.1 Background and motivation for this work
This 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.
1.2 Aims and Research Questions
The 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?
1.4 List of appended papers and author´s contribution
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7 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.2014.10.184
Key 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.
1.1 List of all papers from the author relevant to this thesis
In 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.2016.7752179
Key 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.