TY - JOUR
T1 - Correlation of UV Fluorescence Images with Performance Loss of Field-Retrieved Photovoltaic Modules
AU - Li, Fang
AU - Buddha, Viswa Sai Pavan
AU - Schneller, Eric J.
AU - Iqbal, Nafis
AU - Colvin, Dylan J.
AU - Davis, Kristopher O.
AU - Tamizhmani, Govindasamy
N1 - Funding Information:
Manuscript received December 28, 2020; revised March 22, 2021; accepted April 19, 2021. Date of publication June 2, 2021; date of current version June 21, 2021. This work was supported by the U.S. Department of Energy Solar Energy Technologies Office under Grant DE-EE-0008155. (Corresponding author: Fang Li.) Fang Li, Viswa Sai Pavan Buddha, and GovindaSamy TamizhMani are with the Photovoltaic Reliability Lab, Arizona State University, Mesa, AZ 85212 USA (e-mail: fangli3@asu.edu; vbuddha1@asu.edu; manit@asu.edu).
Publisher Copyright:
© 2011-2012 IEEE.
PY - 2021/7
Y1 - 2021/7
N2 - The ultraviolet fluorescence (UVF) imaging method has been widely used as a rapid and economic field inspection tool for investigating encapsulant discoloration of field-aged photovoltaic (PV) modules. In field-aged PV modules, encapsulant discoloration can result in a pronounced decrease in the short-circuit current. The spatial distribution of environmental stressors and therefore discoloration pattern over each cell of a module depends on the climate. In this article, we investigated the discoloration patterns (and their correlation with electrical parameters of modules and the extracted-cells from the modules) of ten modules produced at the same manufacturing facility and retrieved respectively from two distinct climates of Arizona (hot-dry; seven modules; 18 years of exposure) and Florida (hot-humid; three modules; ten years of exposure). In the Arizona modules, three distinct spatial patterns were observed in the UVF images: cell center region (intense browning); cell edge region (no browning); region between cell center; and cell edge region (light browning). However, in the Florida modules, only two distinct spatial distributions were observed: nonedge cell region (medium browning) and cell edge region (no browning). Furthermore, we employed a high-contrast UVF imaging technique to correlate the interdependence between the encapsulant discoloration pattern and the metallization/contact degradation pattern. For this correlative study, various experimental characterizations were carried out on both field-aged (Arizona and Florida) and unexposed modules and the cells extracted from the modules of the same model and they include: processed UVF and EL images, and I-V, TLM, optical microscopy, and XPS measurements.
AB - The ultraviolet fluorescence (UVF) imaging method has been widely used as a rapid and economic field inspection tool for investigating encapsulant discoloration of field-aged photovoltaic (PV) modules. In field-aged PV modules, encapsulant discoloration can result in a pronounced decrease in the short-circuit current. The spatial distribution of environmental stressors and therefore discoloration pattern over each cell of a module depends on the climate. In this article, we investigated the discoloration patterns (and their correlation with electrical parameters of modules and the extracted-cells from the modules) of ten modules produced at the same manufacturing facility and retrieved respectively from two distinct climates of Arizona (hot-dry; seven modules; 18 years of exposure) and Florida (hot-humid; three modules; ten years of exposure). In the Arizona modules, three distinct spatial patterns were observed in the UVF images: cell center region (intense browning); cell edge region (no browning); region between cell center; and cell edge region (light browning). However, in the Florida modules, only two distinct spatial distributions were observed: nonedge cell region (medium browning) and cell edge region (no browning). Furthermore, we employed a high-contrast UVF imaging technique to correlate the interdependence between the encapsulant discoloration pattern and the metallization/contact degradation pattern. For this correlative study, various experimental characterizations were carried out on both field-aged (Arizona and Florida) and unexposed modules and the cells extracted from the modules of the same model and they include: processed UVF and EL images, and I-V, TLM, optical microscopy, and XPS measurements.
KW - Contact resistance
KW - corrosion
KW - encapsulant browning
KW - performance degradation
KW - short-circuit current
KW - ultraviolet fluorescence imaging
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U2 - 10.1109/JPHOTOV.2021.3075865
DO - 10.1109/JPHOTOV.2021.3075865
M3 - Article
AN - SCOPUS:85107363726
SN - 2156-3381
VL - 11
SP - 926
EP - 935
JO - IEEE Journal of Photovoltaics
JF - IEEE Journal of Photovoltaics
IS - 4
M1 - 9445396
ER -