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Title: Degradation Analysis of Field-Exposed Photovoltaic Modules with Non-Fluoropolymer-Based Backsheets

Abstract

The selection of polymeric materials utilized in photovoltaic (PV) modules has changed relatively little since the inception of the PV industry, with ethylene-vinyl acetate (EVA), polyethylene terephthalate (PET), and fluoropolymer-based laminates being the most widely adopted primary components of the encapsulant and backsheet materials. The backsheet must serve to electrically insulate the solar cells and protect them from the effects of weathering. Due to continued downward pressure on cost, other polymeric materials are being formulated to withstand outdoor exposure for use in backsheets to replace either the PET film, the fluoropoymer film, or both. Because of their relatively recent deployment, less is known about their reliability and if they are durable enough to fulfill the greater than or equal to 25 year warranties of current PV modules. This work presents a degradation analysis of field-exposed modules with polyamide- and polyester-based backsheets. Modules were exposed for up to five years in different geographic locations: USA (Maryland, Ohio), China, and Italy. Surface and cross-sectional analysis included visual inspection, colorimetry, glossimetry, and Fourier-transform infrared spectroscopy. Each module experienced different types of degradation depending on the exposure site, even for the same material and module brand. For instance, the polyamide-based backsheet experienced hairline crackingmore » and greater yellowing and chemical changes in China (Changsu, humid subtropical climate), while in Italy (Rome, hot-summer Mediterranean climate) it underwent macroscopic cracking and greater losses in gloss. Spectroscopic studies have permitted identification of degradation products and changes in polymer structure over time. Comparisons are made to fielded modules with fluoropolymer-based backsheets, as well as backsheet materials in accelerated laboratory exposures. Implications for qualification testing and service life prediction of the non-fluoropolymer-based backsheets are discussed.« less

Authors:
 [1];  [2];  [3];  [3];  [4];  [4];  [5];  [5];  [5];  [6];  [6];  [6];  [2]
  1. National Renewable Energy Laboratory (NREL), Golden, CO (United States)
  2. National Institute of Standards and Technology (NIST)
  3. Northeastern University
  4. Underwriters Laboratory
  5. Arkema
  6. Case Western Reserve University
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S), SunShot Initiative
OSTI Identifier:
1416903
Report Number(s):
NREL/CP-5J00-68229
DOE Contract Number:  
AC36-08GO28308
Resource Type:
Conference
Resource Relation:
Conference: Presented at SPIE Optical Engineering + Applications 2017, 6-10 August 2017, San Diego, California
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; photovoltaic module; backsheet; degradation; polymeric materials; reliability; failure analysis; polyamide; polyethylene terephthalate; polyethylene naphthalate

Citation Formats

Kempe, Michael D, Fairbrother, Andrew, Julien, Scott, Wan, Kai-Tak, Ji, Liang, Boyce, Kenneth, Merzlic, Sebastien, Lefebvre, Amy, O'Brien, Greg, Wang, Yu, Bruckman, Laura, French, Roger, and Gu, Xiaohong. Degradation Analysis of Field-Exposed Photovoltaic Modules with Non-Fluoropolymer-Based Backsheets. United States: N. p., 2017. Web. doi:10.1117/12.2272488.
Kempe, Michael D, Fairbrother, Andrew, Julien, Scott, Wan, Kai-Tak, Ji, Liang, Boyce, Kenneth, Merzlic, Sebastien, Lefebvre, Amy, O'Brien, Greg, Wang, Yu, Bruckman, Laura, French, Roger, & Gu, Xiaohong. Degradation Analysis of Field-Exposed Photovoltaic Modules with Non-Fluoropolymer-Based Backsheets. United States. doi:10.1117/12.2272488.
Kempe, Michael D, Fairbrother, Andrew, Julien, Scott, Wan, Kai-Tak, Ji, Liang, Boyce, Kenneth, Merzlic, Sebastien, Lefebvre, Amy, O'Brien, Greg, Wang, Yu, Bruckman, Laura, French, Roger, and Gu, Xiaohong. Wed . "Degradation Analysis of Field-Exposed Photovoltaic Modules with Non-Fluoropolymer-Based Backsheets". United States. doi:10.1117/12.2272488.
@article{osti_1416903,
title = {Degradation Analysis of Field-Exposed Photovoltaic Modules with Non-Fluoropolymer-Based Backsheets},
author = {Kempe, Michael D and Fairbrother, Andrew and Julien, Scott and Wan, Kai-Tak and Ji, Liang and Boyce, Kenneth and Merzlic, Sebastien and Lefebvre, Amy and O'Brien, Greg and Wang, Yu and Bruckman, Laura and French, Roger and Gu, Xiaohong},
abstractNote = {The selection of polymeric materials utilized in photovoltaic (PV) modules has changed relatively little since the inception of the PV industry, with ethylene-vinyl acetate (EVA), polyethylene terephthalate (PET), and fluoropolymer-based laminates being the most widely adopted primary components of the encapsulant and backsheet materials. The backsheet must serve to electrically insulate the solar cells and protect them from the effects of weathering. Due to continued downward pressure on cost, other polymeric materials are being formulated to withstand outdoor exposure for use in backsheets to replace either the PET film, the fluoropoymer film, or both. Because of their relatively recent deployment, less is known about their reliability and if they are durable enough to fulfill the greater than or equal to 25 year warranties of current PV modules. This work presents a degradation analysis of field-exposed modules with polyamide- and polyester-based backsheets. Modules were exposed for up to five years in different geographic locations: USA (Maryland, Ohio), China, and Italy. Surface and cross-sectional analysis included visual inspection, colorimetry, glossimetry, and Fourier-transform infrared spectroscopy. Each module experienced different types of degradation depending on the exposure site, even for the same material and module brand. For instance, the polyamide-based backsheet experienced hairline cracking and greater yellowing and chemical changes in China (Changsu, humid subtropical climate), while in Italy (Rome, hot-summer Mediterranean climate) it underwent macroscopic cracking and greater losses in gloss. Spectroscopic studies have permitted identification of degradation products and changes in polymer structure over time. Comparisons are made to fielded modules with fluoropolymer-based backsheets, as well as backsheet materials in accelerated laboratory exposures. Implications for qualification testing and service life prediction of the non-fluoropolymer-based backsheets are discussed.},
doi = {10.1117/12.2272488},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2017},
month = {8}
}

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