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Title: A non-destructive method for crack quantification in photovoltaic backsheets under accelerated and real-world exposures

Abstract

The long-term durability of photovoltaic modules is paramount for the continued growth of the industry. Polymer backsheets are of particular concern since they provide electrical insulation and an environmental barrier. In this study, 23 freestanding, multilayer backsheets with nine unique material combinations underwent four different weathering exposures under accelerated and real-world conditions. Besides changes in color and gloss, the induced degradation included parallel or mudflat cracks on 11 backsheets, sometimes in combination with delamination or blistering. Similar degradation has been observed in previous studies and is concerning since cracks compromise the mechanical integrity and electrical safety of backsheets. Quantitative parameters are desirable to reliably classify categories of cracks and supply unbiased features for statistical analysis in predictive lifetime models. We developed an analysis technique that utilizes surface profilometry data to quantify the depth, width, area, spacing, and number of cracks. Parameters are automatically extracted from the raw data by an algorithm running on a high performance distributed computing cluster. Here, our algorithm excelled at characterizing parallel cracks with minimal de-adhesion, and only an estimated 4% of crack detections were false positives. The addition of humidity and temperature variation formed up to three times as many cracks on a photodose basismore » compared to dry, constant temperature exposures. Cracks in real-world and accelerated exposures propagated to similar depths with equivalent photodoses; however, the number of cracks formed in accelerated exposures was far greater on a photodose basis. Of samples that cracked, the best performing backsheet configuration was polyvinyl fluoride/poly (ethylene-terephthalate)/polyethylene (PVF/PET/PE) while the least durable was PET/PET/ethylene-vinyl acetate. None of the six PVF/PET/PVF backsheets cracked in any of the exposures.« less

Authors:
ORCiD logo [1]; ORCiD logo [2];  [1]; ORCiD logo [3]
  1. Case Western Reserve Univ., Cleveland, OH (United States). SDLE Research Center. Dept. of Materials Science and Engineering. Dept. of Mechanical and Aerospace Engineering
  2. Case Western Reserve Univ., Cleveland, OH (United States). SDLE Research Center. Dept. of Materials Science and Engineering; Gebze Technical Univ. (Turkey). Dept. of Materials Science and Engineering
  3. Case Western Reserve Univ., Cleveland, OH (United States). SDLE Research Center. Dept. of Materials Science and Engineering
Publication Date:
Research Org.:
Underwriters Lab LLC, Northbrook, IL (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
OSTI Identifier:
1501895
Grant/Contract Number:  
EE0007143
Resource Type:
Accepted Manuscript
Journal Name:
Polymer Degradation and Stability
Additional Journal Information:
Journal Volume: 153; Journal Issue: C; Journal ID: ISSN 0141-3910
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; photovoltaic; backsheet; cracking; data science; predictive lifetime models; degradation science

Citation Formats

Klinke, Addison G., Gok, Abdulkerim, Ifeanyi, Silas I., and Bruckman, Laura S. A non-destructive method for crack quantification in photovoltaic backsheets under accelerated and real-world exposures. United States: N. p., 2018. Web. doi:10.1016/j.polymdegradstab.2018.05.008.
Klinke, Addison G., Gok, Abdulkerim, Ifeanyi, Silas I., & Bruckman, Laura S. A non-destructive method for crack quantification in photovoltaic backsheets under accelerated and real-world exposures. United States. doi:10.1016/j.polymdegradstab.2018.05.008.
Klinke, Addison G., Gok, Abdulkerim, Ifeanyi, Silas I., and Bruckman, Laura S. Tue . "A non-destructive method for crack quantification in photovoltaic backsheets under accelerated and real-world exposures". United States. doi:10.1016/j.polymdegradstab.2018.05.008. https://www.osti.gov/servlets/purl/1501895.
@article{osti_1501895,
title = {A non-destructive method for crack quantification in photovoltaic backsheets under accelerated and real-world exposures},
author = {Klinke, Addison G. and Gok, Abdulkerim and Ifeanyi, Silas I. and Bruckman, Laura S.},
abstractNote = {The long-term durability of photovoltaic modules is paramount for the continued growth of the industry. Polymer backsheets are of particular concern since they provide electrical insulation and an environmental barrier. In this study, 23 freestanding, multilayer backsheets with nine unique material combinations underwent four different weathering exposures under accelerated and real-world conditions. Besides changes in color and gloss, the induced degradation included parallel or mudflat cracks on 11 backsheets, sometimes in combination with delamination or blistering. Similar degradation has been observed in previous studies and is concerning since cracks compromise the mechanical integrity and electrical safety of backsheets. Quantitative parameters are desirable to reliably classify categories of cracks and supply unbiased features for statistical analysis in predictive lifetime models. We developed an analysis technique that utilizes surface profilometry data to quantify the depth, width, area, spacing, and number of cracks. Parameters are automatically extracted from the raw data by an algorithm running on a high performance distributed computing cluster. Here, our algorithm excelled at characterizing parallel cracks with minimal de-adhesion, and only an estimated 4% of crack detections were false positives. The addition of humidity and temperature variation formed up to three times as many cracks on a photodose basis compared to dry, constant temperature exposures. Cracks in real-world and accelerated exposures propagated to similar depths with equivalent photodoses; however, the number of cracks formed in accelerated exposures was far greater on a photodose basis. Of samples that cracked, the best performing backsheet configuration was polyvinyl fluoride/poly (ethylene-terephthalate)/polyethylene (PVF/PET/PE) while the least durable was PET/PET/ethylene-vinyl acetate. None of the six PVF/PET/PVF backsheets cracked in any of the exposures.},
doi = {10.1016/j.polymdegradstab.2018.05.008},
journal = {Polymer Degradation and Stability},
number = C,
volume = 153,
place = {United States},
year = {2018},
month = {5}
}

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