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Title: Nondestructive Characterization and Accelerated UV Testing of Browned Field-Aged PV Modules

Abstract

Encapsulant browning is one of the most common degradation modes found in crystalline silicon field-aged photovoltaic modules. Browning, usually undetected unless severe, reduces the short-circuit current (Isc) produced by a module. Therefore, field-aged browned modules have been subjected to accelerated UV testing to obtain true end-of-life activation energy for the encapsulant browning mechanism. A novel time- and resource-saving accelerated UV exposure testing method simultaneously allowing multiple module temperatures to be maintained in a single chamber run is presented. Six field-aged crystalline silicon modules of glass/backsheet construction (three each from BP Solar/Solarex MSX 60 and Siemens M55) with similar glass and encapsulant formulation were exposed to a UV dosage of 450 kWh/m2 . Through passive heating, the average module temperatures for the BP Solar/Solarex modules were 60 degrees C, 77 degrees C, and 85 degrees C and those of Siemens M55 were 75 degrees C, 80 degrees C, and 837 degrees C. To study UV browning, the modules were intermittently characterized through visual imaging, UV fluorescence imaging, electroluminescence imaging, quantum efficiency measurements, module, and cell-level light I-V measurements. An Isc decrease corroborated the increased extent of browning with increased module temperature. For the BP Solar/Solarex modules, the Low T, Mid T,more » and the High T modules showed a 1.37%, 2.48%, and 3.26% Isc drop, respectively. The Siemens modules showed a 4.11%, 5.65%, and 6.95% Isc drop. The multiple cell-level Isc data points obtained for each module temperature increased provided statistical significance. Activation energy for encapsulant browning was calculated as 0.44 and 0.72 eV for MSX 60 and M55 modules, respectively.« less

Authors:
 [1];  [1];  [1];  [2];  [1]
  1. Arizona State University
  2. 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), SunShot Initiative
OSTI Identifier:
1573205
Report Number(s):
NREL/JA-5K00-73201
DOE Contract Number:  
AC36-08GO28308
Resource Type:
Journal Article
Journal Name:
IEEE Journal of Photovoltaics
Additional Journal Information:
Journal Volume: 9; Journal Issue: 6
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; accelerated UV exposure; activation energy; characterization; encapsulant browning; field-aged PV modules; nondestructive; UV fluorescence imaging

Citation Formats

Gopalakrishna, Hamsini, Sinha, Archana, Dolia, Kshitiz, Jordan, Dirk, and Tamizhmani, Govindasamy. Nondestructive Characterization and Accelerated UV Testing of Browned Field-Aged PV Modules. United States: N. p., 2019. Web. doi:10.1109/JPHOTOV.2019.2927920.
Gopalakrishna, Hamsini, Sinha, Archana, Dolia, Kshitiz, Jordan, Dirk, & Tamizhmani, Govindasamy. Nondestructive Characterization and Accelerated UV Testing of Browned Field-Aged PV Modules. United States. doi:10.1109/JPHOTOV.2019.2927920.
Gopalakrishna, Hamsini, Sinha, Archana, Dolia, Kshitiz, Jordan, Dirk, and Tamizhmani, Govindasamy. Mon . "Nondestructive Characterization and Accelerated UV Testing of Browned Field-Aged PV Modules". United States. doi:10.1109/JPHOTOV.2019.2927920.
@article{osti_1573205,
title = {Nondestructive Characterization and Accelerated UV Testing of Browned Field-Aged PV Modules},
author = {Gopalakrishna, Hamsini and Sinha, Archana and Dolia, Kshitiz and Jordan, Dirk and Tamizhmani, Govindasamy},
abstractNote = {Encapsulant browning is one of the most common degradation modes found in crystalline silicon field-aged photovoltaic modules. Browning, usually undetected unless severe, reduces the short-circuit current (Isc) produced by a module. Therefore, field-aged browned modules have been subjected to accelerated UV testing to obtain true end-of-life activation energy for the encapsulant browning mechanism. A novel time- and resource-saving accelerated UV exposure testing method simultaneously allowing multiple module temperatures to be maintained in a single chamber run is presented. Six field-aged crystalline silicon modules of glass/backsheet construction (three each from BP Solar/Solarex MSX 60 and Siemens M55) with similar glass and encapsulant formulation were exposed to a UV dosage of 450 kWh/m2 . Through passive heating, the average module temperatures for the BP Solar/Solarex modules were 60 degrees C, 77 degrees C, and 85 degrees C and those of Siemens M55 were 75 degrees C, 80 degrees C, and 837 degrees C. To study UV browning, the modules were intermittently characterized through visual imaging, UV fluorescence imaging, electroluminescence imaging, quantum efficiency measurements, module, and cell-level light I-V measurements. An Isc decrease corroborated the increased extent of browning with increased module temperature. For the BP Solar/Solarex modules, the Low T, Mid T, and the High T modules showed a 1.37%, 2.48%, and 3.26% Isc drop, respectively. The Siemens modules showed a 4.11%, 5.65%, and 6.95% Isc drop. The multiple cell-level Isc data points obtained for each module temperature increased provided statistical significance. Activation energy for encapsulant browning was calculated as 0.44 and 0.72 eV for MSX 60 and M55 modules, respectively.},
doi = {10.1109/JPHOTOV.2019.2927920},
journal = {IEEE Journal of Photovoltaics},
number = 6,
volume = 9,
place = {United States},
year = {2019},
month = {9}
}