Title: Field testing of thermoplastic encapsulants in high‐temperature installations

Abstract

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 ofmore » 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.« less

Authors:

Kempe, Michael D. ^[1]; Miller, David C. ^[1]; Wohlgemuth, John H. ^[1]; Kurtz, Sarah R. ^[1]; Moseley, John M. ^[1]; Shah, Qurat A. ^[2]; Tamizhmani, Govindasamy ^[2]; Sakurai, Keiichiro ^[3]; Inoue, Masanao ^[4]; Doi, Takuya ^[4]; Masuda, Atsushi ^[4]; Samuels, Sam L. ^[5]; Vanderpan, Crystal E. ^[6]

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+ Show Author Affiliations

1. National Renewable Energy Laboratory 15013 Denver West Parkway Golden Colorado 80401
2. Arizona State University Photovoltaic Reliability Laboratory 7349 East Unity Avenue Mesa Arizona
3. 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
4. National Institute of Advanced Industrial Science and Technology 807‐1, Shuku‐Machi Tosu Saga 841‐0052 Japan
5. DuPont Company 200 Powder Mill Road Wilmington Delaware 19803
6. Underwriters Laboratories 455 East Trimble Road San Jose California

Publication Date:

Wed Nov 25 00:00:00 EST 2015

Research Org.:

National Renewable Energy Laboratory (NREL), Golden, CO (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office

OSTI Identifier:

1233866

Alternate Identifier(s):

OSTI ID: 1233684; OSTI ID: 1233867

Report Number(s):

NREL/JA-5J00-62417
Journal ID: ISSN 2050-0505

Grant/Contract Number:  

DE‐AC36‐08‐GO28308; AC36-08GO28308

Resource Type:

Published Article

Journal Name:

Energy Science & Engineering

Additional Journal Information:

Journal Name: Energy Science & Engineering Journal Volume: 3 Journal Issue: 6; Journal ID: ISSN 2050-0505

Publisher:

Wiley Blackwell (John Wiley & Sons)

Country of Publication:

United Kingdom

Language:

English

Subject:

14 SOLAR ENERGY; 36 MATERIALS SCIENCE; Encapsulant; Adhesives; Creep; Thermoplastic; Qualification Standards; Polymer