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FEM-based development of novel back-contact PV modules with ultra-thin solar cells

: Beinert, Andreas; Leidl, Roman; Sommeling, Paul; Eitner, Ulrich; Aktaa, Jarir

Volltext urn:nbn:de:0011-n-4774434 (535 KByte PDF)
MD5 Fingerprint: 988c6dcec1c8f8d0f539d89fa6341750
Erstellt am: 13.1.2018

Smets, A.:
33rd European Photovoltaic Solar Energy Conference and Exhibition, EU PVSEC 2017 : Proceedings of the international conference held in Amsterdam, The Netherlands, 25 September - 29 September 2017
München: WIP, 2017
ISBN: 978-3-936338-47-8
ISBN: 3-936338-47-7
European Photovoltaic Solar Energy Conference and Exhibition (EU PVSEC) <33, 2017, Amsterdam>
European Commission EC
FP7-Energy - Integrated research programme in the field of photovoltaics; 609788; CHEETAH
Cost-reduction through material optimisation and Higher EnErgy outpuT of solAr pHotovoltaic modules - joining Europe’s Research and Development efforts in support of its PV industry
Konferenzbeitrag, Elektronische Publikation
Fraunhofer ISE ()
photovoltaisches Modul; Systeme und Zuverlässigkeit; Photovoltaik; Photovoltaische Module und Kraftwerke; Modultechnologie; stress; solar cell; modeling; characterization; module design; thermomechanical stress; thin solar cell; FEM modeling; material characterization; PV module design

With the availability of ultra-thin back contact solar cells, the question arises if they can be integrated into PV modules. Particularly the single-side metallization and joint architecture of back contact solar cells may cause critical stress. We develop a three-dimensional finite element model of a frameless 60-cell module with an electrically conductive backsheet to simulate the cell stress in terms of mechanical push load. The FEM model is validated by mechanical load tests of frameless modules. With the validated model we perform a variation of the cell and encapsulant thickness from 80 μm to 180 μm and 200 μm to 460 μm, respectively. Moreover we compare three different encapsulant materials, one Ethylene-vinyl acetate copolymer (EVA), one thermoset Polyolefin elastomer (POE-TS), one thermoplastic POE (POE-TP) and two different electrically conductive adhesives. The combination of 460 μm thick EVA and 180 μm cells shows the lowest first principal stress which, however, is far above the measured critical fracture stress of 134 MPa for the MWT cells used. We then modify the FEM model to simulate a framed glass-foil as well as a framed and frameless glass-glass module with the same material combination, 80 μm cells and 200 μm encapsulant. The framed glass-foil module shows a by 54% reduced deflection and a stress of 114 MPa, which is much smaller than without a frame (296 MPa). The lowest value is achieved for the framed glassglass module with 66 MPa. An interesting finding from the thickness variation is, that for cells below about 110 μm thickness the stress increases with increasing encapsulant thickness, while for thicker cells the stress decreases.