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Title: Generalized Spatio-Temporal Model of Backsheet Degradation From Field Surveys of Photovoltaic Modules

Abstract

Photovoltaic (PV) module backsheets degrade at different rates because of the specific polymeric materials and the local exposure environments of the installations. Studies of real-world backsheet degradation provide valuable information to understand backsheet degradation and failure. Field surveys of PV module backsheets were conducted on 1310 modules in four commercial PV power plant sites with different exposure times. The backsheet's local exposure environment is determined by its location along the rack length and depth, the modules' elevation above the ground, and the ground cover albedo. Backsheets that are installed at the ends of the module rack length exhibit larger degradation rates (with yellowness index difference of 1.14 $$\pm$$ 0.45 and 7.80 $$\pm$$ 1.3 for backsheets of poly (ethylene terephthalate) and poly (ethylene naphthalate) as the air-side layer, respectively) than backsheets in the center section of the rack. A generalized spatio-temporal model was developed to predict the large-scale backsheet degradation of different backsheet polymers across time/age and location in the PV power plant rack. The model utilizes a cubic-spline relationship between backsheet degradation and rack length, and a quadratic relationship between backsheet discoloration and rack depth. This generalized spatio-temporal model predicts the outdoor backsheet degradation with an adjusted- $R^2$ range between 0.31 to 0.89. The similarity between this model and the spatial variation of the rear-side irradiance, indicates that the irradiance plays a significant role in outdoor backsheet degradation. The generalized spatio-temporal model can be used to evaluate large scale PV backsheet performance, as well as a guidance for PV site designers and operations and maintenance crews.

Authors:
 [1];  [2];  [3];  [1];  [1];  [1];  [4];  [4];  [5];  [3];  [4];  [5];  [6];  [7];  [6];  [1];  [1]
  1. Case Western Reserve University
  2. Case Western Reserve University; Feng Chia University
  3. National Institute of Standards and Technology
  4. Arkema, Inc.
  5. Northeastern University
  6. Underwriters Laboratories, Inc.
  7. National Renewable Energy Laboratory (NREL), Golden, CO (United States)
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)
OSTI Identifier:
1567038
Report Number(s):
NREL/JA-5K00-74973
DOE Contract Number:  
AC36-08GO28308
Resource Type:
Journal Article
Journal Name:
IEEE Journal of Photovoltaics
Additional Journal Information:
Journal Volume: 9; Journal Issue: 5
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; backsheet degradation; field survey; photovoltaic module; spatio-temporal model

Citation Formats

Wang, Yu, Huang, Wei-Heng, Fairbrother, Andrew, Fridman, Lucas S., Curran, Alan J., Wheeler, Nicholas R., Napoli, Sophie, Hauser, Adam W., Julien, Scott, Gu, Xiaohong, O'Brien, Gregory S., Wan, Kai-Tak, Ji, Liang, Kempe, Michael D, Boyce, Kenneth P., French, Roger H., and Bruckman, Laura S. Generalized Spatio-Temporal Model of Backsheet Degradation From Field Surveys of Photovoltaic Modules. United States: N. p., 2019. Web. doi:10.1109/JPHOTOV.2019.2928700.
Wang, Yu, Huang, Wei-Heng, Fairbrother, Andrew, Fridman, Lucas S., Curran, Alan J., Wheeler, Nicholas R., Napoli, Sophie, Hauser, Adam W., Julien, Scott, Gu, Xiaohong, O'Brien, Gregory S., Wan, Kai-Tak, Ji, Liang, Kempe, Michael D, Boyce, Kenneth P., French, Roger H., & Bruckman, Laura S. Generalized Spatio-Temporal Model of Backsheet Degradation From Field Surveys of Photovoltaic Modules. United States. doi:10.1109/JPHOTOV.2019.2928700.
Wang, Yu, Huang, Wei-Heng, Fairbrother, Andrew, Fridman, Lucas S., Curran, Alan J., Wheeler, Nicholas R., Napoli, Sophie, Hauser, Adam W., Julien, Scott, Gu, Xiaohong, O'Brien, Gregory S., Wan, Kai-Tak, Ji, Liang, Kempe, Michael D, Boyce, Kenneth P., French, Roger H., and Bruckman, Laura S. Fri . "Generalized Spatio-Temporal Model of Backsheet Degradation From Field Surveys of Photovoltaic Modules". United States. doi:10.1109/JPHOTOV.2019.2928700.
@article{osti_1567038,
title = {Generalized Spatio-Temporal Model of Backsheet Degradation From Field Surveys of Photovoltaic Modules},
author = {Wang, Yu and Huang, Wei-Heng and Fairbrother, Andrew and Fridman, Lucas S. and Curran, Alan J. and Wheeler, Nicholas R. and Napoli, Sophie and Hauser, Adam W. and Julien, Scott and Gu, Xiaohong and O'Brien, Gregory S. and Wan, Kai-Tak and Ji, Liang and Kempe, Michael D and Boyce, Kenneth P. and French, Roger H. and Bruckman, Laura S.},
abstractNote = {Photovoltaic (PV) module backsheets degrade at different rates because of the specific polymeric materials and the local exposure environments of the installations. Studies of real-world backsheet degradation provide valuable information to understand backsheet degradation and failure. Field surveys of PV module backsheets were conducted on 1310 modules in four commercial PV power plant sites with different exposure times. The backsheet's local exposure environment is determined by its location along the rack length and depth, the modules' elevation above the ground, and the ground cover albedo. Backsheets that are installed at the ends of the module rack length exhibit larger degradation rates (with yellowness index difference of 1.14 $\pm$ 0.45 and 7.80 $\pm$ 1.3 for backsheets of poly (ethylene terephthalate) and poly (ethylene naphthalate) as the air-side layer, respectively) than backsheets in the center section of the rack. A generalized spatio-temporal model was developed to predict the large-scale backsheet degradation of different backsheet polymers across time/age and location in the PV power plant rack. The model utilizes a cubic-spline relationship between backsheet degradation and rack length, and a quadratic relationship between backsheet discoloration and rack depth. This generalized spatio-temporal model predicts the outdoor backsheet degradation with an adjusted- $R^2$ range between 0.31 to 0.89. The similarity between this model and the spatial variation of the rear-side irradiance, indicates that the irradiance plays a significant role in outdoor backsheet degradation. The generalized spatio-temporal model can be used to evaluate large scale PV backsheet performance, as well as a guidance for PV site designers and operations and maintenance crews.},
doi = {10.1109/JPHOTOV.2019.2928700},
journal = {IEEE Journal of Photovoltaics},
number = 5,
volume = 9,
place = {United States},
year = {2019},
month = {8}
}