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Industrial biPERC Solar Cells with Varied Rear Side Characteristics under Bifacial Illumination

: Wöhrle, N.; Fellmeth, T.; Krieg, A.; Palinginis, P.; Weber, T.; Steckemetz, S.; Ramspeck, K.; Greulich, J.; Rein, S.

Fulltext urn:nbn:de:0011-n-5486036 (765 KByte PDF)
MD5 Fingerprint: ed8992f817f6c92499c305cfe9734e74
Created on: 18.6.2019

Verlinden, P. ; WIP - Renewable Energies, München:
35th European Photovoltaic Solar Energy Conference and Exhibition 2018 : Proceedings of the international conference held in Brussels, Belgium, 24 September-28 September 2018; DVD-ROM
München: WIP, 2018
ISBN: 978-3-936338-50-8
ISBN: 3-936338-50-7
European Photovoltaic Solar Energy Conference and Exhibition (EU PVSEC) <35, 2018, Brussels>
Conference Paper, Electronic Publication
Fraunhofer ISE ()
Inline-Solarzellenanalytik und Simulation; Photovoltaik; Silicium-Photovoltaik; Messtechnik und Produktionskontrolle; solar cell; PERC; passivation; texture; bifaciality

Bifacial solar cells pose the challenge of optimizing a solar cell’s rear side towards two opposing aspects: The front side efficiency and the rear side efficiency. After a previous work of the authors has dealt with the aspects of optimizing the grid this work focusses on the passivation thickness and the rear side roughness in optical and electrical aspects. A solar cell batch with 20.6% front and 13.5% rear peak efficiency has been produced. It contains a variation of rear side capping thickness, i.e. colors, as well as planarized and textured rear surfaces which are compared under different bifacial illumination scenarios with a pure front as well as a pure rear irradiance of 1000 W/m², as well as 1000 W/m² front and added rear irradiance of 100, 300 and 500 W/m². It has been found that a textured rear surface is capable of capturing more light shining onto the rear surface, but also exhibits enhanced rear surface recombination. Under 1000 W/m² front irradiance, the threshold for rear irradiance necessary to reach parity in terms of output power between a planarized and a textured rear surface PERC is found to be between 300 and 500 W/m² on cell level using an optimal SiNx capping thickness of 60 nm for the planar and 80 nm for the textured surface. In compound with module encapsulant the rear texture’s optical trapping advantage for rear irradiated light diminishes further, increasing the required rear irradiance for output power parity above 500 W/m². The development of PERC cells with bifacialities exceeding 70% could also increase the influence of rear side optics favoring textured rear sides.