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Assessment of the impact of stagnation temperatures in receiver prototypes of C-PVT collectors
University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building Engineering, Energy Systems and Sustainability Science, Energy Systems and Building Technology.ORCID iD: 0000-0002-8156-2587
2019 (English)In: Energies, E-ISSN 1996-1073, Vol. 12, no 15, p. 2967-2967Article in journal (Refereed) Published
Abstract [en]

Concentrating Photovoltaic Thermal (C-PVT) solar collectors produce both thermal and electric power from the same area while concentrating sunlight. This paper studies a C-PVT design where strings of series-connected solar cells are encapsulated with silicone in an aluminium receiver, inside of which the heat transfer fluid flows, and presents an evaluation on structural integrity and performance, after reaching stagnation temperatures. Eight test receivers were made, in which the following properties were varied: Size of the PV cells, type of silicone used to encapsulate the cells, existence of a strain relief between the cells, size of the gap between cells, and type of cell soldering (line or point). The test receivers were placed eight times in an oven for one hour at eight different monitored temperatures. The temperature of the last round was set at 220 °C, which exceeds the highest temperature the panel design reaches. Before and after each round in the oven, the following tests were conducted to the receivers: Electroluminescence (EL) test, IV-curve tracing, diode function, and visual inspection. The test results showed that the receivers made with the transparent silicone and strain relief between cells experienced less microcracks and lower power degradation. No prototype test receiver lost more than 30% of its initial power, despite some receivers displaying a large number of cell cracks. The transparent and more elastic silicone is better at protecting the solar cells from the mechanical stress of thermal expansion than the compared silicone alternative, which was stiffer. As expected, larger cells are more prone to develop microcracks after exposure to thermal stress. Additionally, existing microcracks tend to grow in size relatively fast under thermal stress. EL imaging taken during our experiment leads us to conclude that it is far more likely for existing cracks to expand than for new cracks to appear. [ABSTRACT FROM AUTHOR]

Place, publisher, year, edition, pages
MDPI , 2019. Vol. 12, no 15, p. 2967-2967
Keywords [en]
Concentration, Electroluminescence test, IV-curve, PVT, Stagnation temperature
National Category
Other Engineering and Technologies
Research subject
Sustainable Urban Development
Identifiers
URN: urn:nbn:se:hig:diva-30571DOI: 10.3390/en12152967ISI: 000482174800126Scopus ID: 2-s2.0-85073703419OAI: oai:DiVA.org:hig-30571DiVA, id: diva2:1345318
Note

Funding agency:

- Eureka Eurostars, Project E10625—Solar CPC PVT Production- Solarus Sunpower (company)

Available from: 2019-08-23 Created: 2019-08-23 Last updated: 2025-10-02Bibliographically approved
In thesis
1. Development of Concentrating Photovoltaic-Thermal Solar Collectors
Open this publication in new window or tab >>Development of Concentrating Photovoltaic-Thermal Solar Collectors
2021 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Fossil fuels have greatly improved human living standards and saved countless lives. However, today, their continued use threatens human survival, as CO2 levels rise at an unprecedented pace to levels never seen during human existenceon earth.

This thesis aims at gathering knowledge on solar energy in general and photovoltaic thermal (PVT) and concentrating photovoltaic thermal (C-PVT) in particular. This thesis establishes several key research questions for PVTs and C-PVT collectors and attempts to answer them.

A comprehensive market study of solar thermal (ST), photovoltaic (PV) and PVT was conducted to obtain prices and performance. Simulations of the energy output around the world were conducted. A ratio between ST and PV annual output was defined to serve as a tool for comparison and plotted on a world map.

A key issue for PVT collectors is how to encapsulate the solar cells in a way that, amongst other things, protects the cell from the thermal expansion of the receiver, has a high transparency, and insulates electrically while at the same time conducts the heat to the receiver. In order to be useful, this analysis must also consider the impacts on the production processes. Several prototypes were constructed, a test methodology was created, and the analysis of the results enabled several conclusions on the validity of the different silicon encapsulations methods.

This thesis relies heavily on collector testing with 30 different prototypes of C-PVTs being designed and constructed. Most testing was conducted using steady state method but quasi dynamic was also carried out. From this work, several guidelines were created for the design of collectors in terms of reflector geometry, cell size, string configuration, encapsulation method and several other design aspects. These analyses were complemented with thermal simulations (COMSOL & ANSYS), string layout (LT SPICE) and evaluation of existing installations. Two novel design ideas came from this thesis work, which the author will patent in the coming year. Additionally, raytracing work has been conducted and a new reflector geometry more appropriate for C-PVTs has been found to significantly improve the annual performance. Finally, the current and future position of PVTs in the global energy market is discussed.

Abstract [sv]

Denna avhandling syftar till att samla kunskaper om solenergi i allmänhet och PVT-hybrider som ger både el och värme i synnerhet. Särskilt stort intresse riktas mot koncentrerande C-PVT-hybrider.

Avhandlingen ställer ett flertal viktiga forskningsfrågor för PVT och CPVT solfångare och försöker svara på dem. En omfattande marknadsstudie av solvärme (ST), solceller (PV) och PVT har genmförts för att erhålla priser och prestanda.

Studien användes som underlag för energiutbytessimuleringar runt om i världen. Ett förhållande för kvoten mellan energiutbytena för ST och PV definierades för att användas som ett verktyg för en jämförelse mellan systemen och ritades in på världskartan.

En viktig fråga för PVT-solfångare är hur man kapslar in solcellerna på ett sätt som bland annat skyddar solcellen från absorbatorns värmeutvidgning, har hög transparens och isolerar elektriskt samtidigt som den leder värmen till absorbatorn. För att vara användbar måste denna analys också ta hänsyn till produktionsprocesserna. Flera prototyper konstruerades, en testmetod utarbetades och analysen av resultaten möjliggjorde ett antal viktiga slutsatser om funktionen hos de olika silikoninkapslingsmetoderna.

Denna avhandling baseras på verkningsgradstestning av 30 olika prototyper av C-PVT. De flesta testerna utfördes med den statiska testmetoden, men kvasidynamisk testning har också använts. Från denna testning utarbetades riktlinjer för konstruktionen av solfångarna när det gäller reflektorgeometri, cellstorlek, strängkonfiguration och inkapslingsmetod. Dessa analyser kompletterades med termiska simuleringar (COMSOL & ANSYS), stränglayout (LT SPICE)och utvärdering av befintliga installationer. Ett antal nya designidéer kommer att patenteras under de kommande åren. En ny reflektorgeometri för C-PVT som förbättrar det årliga energiutbytet har utarbetats och testats. Slutligen diskuteras PVTs nuvarande och framtida position på den globala marknaden försolenergisystem.

Place, publisher, year, edition, pages
Gävle: Gävle University Press, 2021. p. 194
Series
Doctoral thesis ; 21
Keywords
Solar Energy, Photovoltaic-Thermal (PVT), Concentration, Collector Testing, Silicon Cell Encapsulation, Ray Tracing, Market Survey, String Layout, Prototype Collectors, Solenergi, Fotovoltaisk-termisk (PVT), Koncentration, Solfångarprovning, Inkapsling av kiselceller, Strålgångsberäkning, Marknadsundersökning, Strängdesign, Solfångarprototyper
National Category
Energy Engineering
Research subject
Sustainable Urban Development
Identifiers
urn:nbn:se:hig:diva-35411 (URN)978-91-88145-67-3 (ISBN)978-91-88145-68-0 (ISBN)
Public defence
2021-08-27, Room 13:111, Kungsbäcksvägen 47, Gävle, 10:15 (English)
Opponent
Supervisors
Available from: 2021-06-17 Created: 2021-03-09 Last updated: 2025-10-02Bibliographically approved

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