TY - JOUR
T1 - Nondestructive Characterization and Accelerated UV Testing of Browned Field-Aged PV Modules
AU - Gopalakrishna, Hamsini
AU - Sinha, Archana
AU - Dolia, Kshitiz
AU - Jordan, Dirk
AU - Tamizhmani, Govindasamy
N1 - Funding Information:
Manuscript received February 8, 2019; revised May 6, 2019 and June 30, 2019; accepted July 3, 2019. Date of publication September 9, 2019; date of current version October 28, 2019. This work was supported by the Department of Energy (Award number DE-EE0007138), as a part of the PREDICTS 2 program under the SunShot initiative. (Corresponding author: Hamsini Gopalakrishna.) H. Gopalakrishna, A. Sinha, and G. Tamizhmani are with the Department of Systems Engineering, Arizona State University, Mesa, AZ 85212 USA (e-mail: hamsini.gopalakrishna@asu.edu; archana.sinha@asu.edu; manit@ asu.edu).
Publisher Copyright:
© 2011-2012 IEEE.
PY - 2019/11
Y1 - 2019/11
N2 - 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 °C, 77 °C, and 85 °C and those of Siemens M55 were 75 °C, 80 °C, and 837 °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.
AB - 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 °C, 77 °C, and 85 °C and those of Siemens M55 were 75 °C, 80 °C, and 837 °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.
KW - Accelerated UV exposure
KW - UV fluorescence imaging
KW - activation energy
KW - characterization
KW - encapsulant browning
KW - field-aged PV modules
KW - nondestructive
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U2 - 10.1109/JPHOTOV.2019.2927920
DO - 10.1109/JPHOTOV.2019.2927920
M3 - Article
AN - SCOPUS:85077515447
SN - 2156-3381
VL - 9
SP - 1733
EP - 1740
JO - IEEE Journal of Photovoltaics
JF - IEEE Journal of Photovoltaics
IS - 6
M1 - 8827711
ER -