
Multi angle laser light scattering evaluation of field exposed thermoplastic photovoltaic encapsulant materials
Author(s) -
Kempe Michael D.,
Miller David C.,
Wohlgemuth John H.,
Kurtz Sarah R.,
Moseley John M.,
Nobles Dylan L.,
Stika Katherine M.,
Brun Yefim,
Samuels Sam L.,
Shah Qurat Annie,
Tamizhmani Govindasamy,
Sakurai Keiichiro,
Inoue Masanao,
Doi Takuya,
Masuda Atsushi,
Vanderpan Crystal E.
Publication year - 2016
Publication title -
energy science and engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.638
H-Index - 29
ISSN - 2050-0505
DOI - 10.1002/ese3.106
Subject(s) - materials science , creep , thermoplastic , thermoplastic polyurethane , composite material , polymer , photovoltaic system , polyvinyl acetate , thermoplastic elastomer , copolymer , elastomer , ecology , biology
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.