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Title: Encapsulant Adhesion to Surface Metallization on Photovoltaic Cells

Abstract

Delamination of encapsulant materials from PV cell surfaces often appears to originate at regions with metallization. Using a fracture mechanics based metrology, the adhesion of ethylene vinyl acetate (EVA) encapsulant to screen-printed silver metallization was evaluated. At room temperature, the fracture energy Gc [J/m2] of the EVA/silver interface (952 J/m2) was ~70% lower than that of the EVA/antireflective (AR) coating (>2900 J/m2) and ~60% lower than that of the EVA to the surface of cell (2265 J/m2). After only 300 h of damp heat aging, the adhesion energy of the silver interface dropped to and plateaued at ~50-60 J/m2 while that of the EVA/AR coating and EVA/cell remained mostly unchanged. Elemental surface analysis showed that the EVA separates from the silver in a purely adhesive manner, indicating that bonds at the interface were likely displaced in the presence of humidity and chemical byproducts at elevated temperature, which in part accounts for the propensity of metalized surfaces to delaminate in the field.

Authors:
ORCiD logo; ORCiD logo;
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:
1411520
Report Number(s):
NREL/JA-5J00-70596
Journal ID: ISSN 2156-3381
DOE Contract Number:
AC36-08GO28308
Resource Type:
Journal Article
Resource Relation:
Journal Name: IEEE Journal of Photovoltaics; Journal Volume: 7; Journal Issue: 6
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 36 MATERIALS SCIENCE; PV module reliability; encapsulant; EVA; adhesion; metallization

Citation Formats

Tracy, Jared, Bosco, Nick, and Dauskardt, Reinhold. Encapsulant Adhesion to Surface Metallization on Photovoltaic Cells. United States: N. p., 2017. Web. doi:10.1109/JPHOTOV.2017.2746572.
Tracy, Jared, Bosco, Nick, & Dauskardt, Reinhold. Encapsulant Adhesion to Surface Metallization on Photovoltaic Cells. United States. doi:10.1109/JPHOTOV.2017.2746572.
Tracy, Jared, Bosco, Nick, and Dauskardt, Reinhold. Wed . "Encapsulant Adhesion to Surface Metallization on Photovoltaic Cells". United States. doi:10.1109/JPHOTOV.2017.2746572.
@article{osti_1411520,
title = {Encapsulant Adhesion to Surface Metallization on Photovoltaic Cells},
author = {Tracy, Jared and Bosco, Nick and Dauskardt, Reinhold},
abstractNote = {Delamination of encapsulant materials from PV cell surfaces often appears to originate at regions with metallization. Using a fracture mechanics based metrology, the adhesion of ethylene vinyl acetate (EVA) encapsulant to screen-printed silver metallization was evaluated. At room temperature, the fracture energy Gc [J/m2] of the EVA/silver interface (952 J/m2) was ~70% lower than that of the EVA/antireflective (AR) coating (>2900 J/m2) and ~60% lower than that of the EVA to the surface of cell (2265 J/m2). After only 300 h of damp heat aging, the adhesion energy of the silver interface dropped to and plateaued at ~50-60 J/m2 while that of the EVA/AR coating and EVA/cell remained mostly unchanged. Elemental surface analysis showed that the EVA separates from the silver in a purely adhesive manner, indicating that bonds at the interface were likely displaced in the presence of humidity and chemical byproducts at elevated temperature, which in part accounts for the propensity of metalized surfaces to delaminate in the field.},
doi = {10.1109/JPHOTOV.2017.2746572},
journal = {IEEE Journal of Photovoltaics},
number = 6,
volume = 7,
place = {United States},
year = {Wed Nov 01 00:00:00 EDT 2017},
month = {Wed Nov 01 00:00:00 EDT 2017}
}