Multi angle laser light scattering evaluation of field exposed thermoplastic photovoltaic encapsulant materials

Journal Article · Fri Jan 08 04:00:00 UTC 2016 · Energy Science & Engineering

DOI: https://doi.org/10.1002/ese3.106 · OSTI ID:1234272

Kempe, Michael D. ^[1]; Miller, David C. ^[1]; Wohlgemuth, John H. ^[1]; Kurtz, Sarah R. ^[1]; Moseley, John M. ^[1]; Nobles, Dylan L. ^[1]; Stika, Katherine M. ^[2]; Brun, Yefim ^[2]; Samuels, Sam L. ^[2]; Shah, Qurat (Annie) ^[3]; Tamizhmani, Govindasamy ^[3]; Sakurai, Keiichiro ^[4]; Inoue, Masanao ^[4]; Doi, Takuya ^[4]; Masuda, Atsushi ^[4]; Vanderpan, Crystal E. ^[5]

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1. National Renewable Energy Laboratory 1617 Cole Boulevard Golden Colorado 80401
2. DuPont Company 200 Powder Mill Road Wilmington Delaware 19803
3. Polytechnic Campus Arizona State University 7349 East Unity Avenue Mesa Arizona
4. National Institute of Advanced Industrial Science and Technology 1‐1‐1 Umezono Tsukuba Ibaraki 305‐8568 Japan
5. Underwriters Laboratories 455 East Trimble Road San Jose California

Abstract As creep of polymeric materials is potentially a safety concern for photovoltaic modules, the potential for module creep has become a significant topic of discussion in the development of IEC 61730 and IEC 61215. To investigate the possibility of creep, modules were constructed, using several thermoplastic encapsulant materials, into thin‐film mock modules and deployed in Mesa, Arizona. The materials examined included poly(ethylene)‐co‐vinyl acetate (EVA, including formulations both cross‐linked and with no curing agent), polyethylene/polyoctene copolymer (PO), poly(dimethylsiloxane) (PDMS), polyvinyl butyral (PVB), and thermoplastic polyurethane (TPU). The absence of creep in this experiment is attributable to several factors of which the most notable one was the unexpected cross‐linking of an EVA formulation without a cross‐linking agent. It was also found that some materials experienced both chain scission and cross‐linking reactions, sometimes with a significant dependence on location within a module. The TPU and EVA samples were found to degrade with cross‐linking reactions dominating over chain scission. In contrast, the PO materials degraded with chain scission dominating over cross‐linking reactions. Although we found no significant indications that viscous creep is likely to occur in fielded modules capable of passing the qualification tests, we note that one should consider how a polymer degrades, chain scission or cross‐linking, in assessing the suitability of a thermoplastic polymer in terrestrial photovoltaic applications.

• Sponsoring Organization: USDOE
• Grant/Contract Number: AC36-08GO28308
• OSTI ID: 1234272
• Journal Information: Energy Science & Engineering, Journal Name: Energy Science & Engineering Journal Issue: 1 Vol. 4; ISSN 2050-0505
• Publisher: Wiley Blackwell (John Wiley & Sons)Copyright Statement
• Country of Publication: United Kingdom
• Language: English