Field testing of thermoplastic encapsulants in high‐temperature installations
- National Renewable Energy Laboratory 15013 Denver West Parkway Golden Colorado 80401
- Arizona State University Photovoltaic Reliability Laboratory 7349 East Unity Avenue Mesa Arizona
- National Renewable Energy Laboratory 15013 Denver West Parkway Golden Colorado 80401, National Institute of Advanced Industrial Science and Technology 1‐1‐1 Umezono Tsukuba Ibaraki 305‐8568 Japan
- National Institute of Advanced Industrial Science and Technology 807‐1, Shuku‐Machi Tosu Saga 841‐0052 Japan
- DuPont Company 200 Powder Mill Road Wilmington Delaware 19803
- Underwriters Laboratories 455 East Trimble Road San Jose California
Abstract Recently there has been increased interest in using thermoplastic encapsulant materials in photovoltaic modules, but concerns have been raised about whether these would be mechanically stable at high temperatures in the field. Recently, this has become a significant topic of discussion in the development of IEC 61730 and IEC 61215. We constructed eight pairs of crystalline‐silicon modules and eight pairs of glass/encapsulation/glass thin‐film mock modules using different encapsulant materials, of which only two were formulated to chemically crosslink. One module set was exposed outdoors with thermal insulation on the back side in Mesa, Arizona, in the summer (hot‐dry), and an identical module set was exposed in environmental chambers. High‐precision creep measurements (±20 μ m) and electrical performance measurements indicate that despite many of these polymeric materials operating in the melt or rubbery state during outdoor deployment, no significant creep was seen because of their high viscosity, lower operating temperature at the edges, and/or the formation of chemical crosslinks in many of the encapsulants with age despite the absence of a crosslinking agent. Only an ethylene‐vinyl acetate ( EVA ) encapsulant formulated without a peroxide crosslinking agent crept significantly. In the case of the crystalline‐silicon modules, the physical restraint of the backsheet reduced creep further and was not detectable even for the EVA without peroxide. Because of the propensity of some polymeric materials to crosslink as they age, typical thermoplastic encapsulants would be unlikely to result in creep in the vast majority of installations.
- Research Organization:
- National Renewable Energy Laboratory (NREL), Golden, CO (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office
- Grant/Contract Number:
- DE‐AC36‐08‐GO28308; AC36-08GO28308
- OSTI ID:
- 1233866
- Alternate ID(s):
- OSTI ID: 1233684; OSTI ID: 1233867
- Report Number(s):
- NREL/JA-5J00-62417
- Journal Information:
- Energy Science & Engineering, Journal Name: Energy Science & Engineering Vol. 3 Journal Issue: 6; ISSN 2050-0505
- Publisher:
- Wiley Blackwell (John Wiley & Sons)Copyright Statement
- Country of Publication:
- United Kingdom
- Language:
- English
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