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Title: Defining Threshold Values of Encapsulant and Backsheet Adhesion for PV Module Reliability

Abstract

The width-tapered cantilever beam method is used to quantify the debond energy (adhesion) of encapsulant and backsheet structures of 32 modules collected from the field. The collected population of modules contains both those that have remained intact and those with instances of either or both encapsulant and backsheet delamination. From this survey, initial threshold values (an adhesion value above which a module should remain intact throughout its lifetime) for encapsulant and backsheet interfaces are proposed. For encapsulants this value is ~ 160J/m 2 and for backsheets ~ 10J/m 2. Here, it is expected that these values will continue to be refined and evolve as the width-tapered cantilever beam method gets adopted by the PV industry, and that they may aid in the future improvement of accelerated lifetime tests and the development of new, low-cost materials.

Authors:
ORCiD logo [1];  [1];  [1]; ORCiD logo [2];  [2]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  2. Stanford Univ., Stanford, CA (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:
1405279
Report Number(s):
NREL/JA-5J00-69023
Journal ID: ISSN 2156-3381
Grant/Contract Number:
AC36-08GO28308
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
IEEE Journal of Photovoltaics
Additional Journal Information:
Journal Volume: 7; Journal Issue: 6; Journal ID: ISSN 2156-3381
Publisher:
IEEE
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 42 ENGINEERING; adhesive strength; reliability; photovoltaic cells

Citation Formats

Bosco, Nick, Eafanti, Joshua, Kurtz, Sarah, Tracy, Jared, and Dauskardt, Reinhold. Defining Threshold Values of Encapsulant and Backsheet Adhesion for PV Module Reliability. United States: N. p., 2017. Web. doi:10.1109/JPHOTOV.2017.2746682.
Bosco, Nick, Eafanti, Joshua, Kurtz, Sarah, Tracy, Jared, & Dauskardt, Reinhold. Defining Threshold Values of Encapsulant and Backsheet Adhesion for PV Module Reliability. United States. doi:10.1109/JPHOTOV.2017.2746682.
Bosco, Nick, Eafanti, Joshua, Kurtz, Sarah, Tracy, Jared, and Dauskardt, Reinhold. Wed . "Defining Threshold Values of Encapsulant and Backsheet Adhesion for PV Module Reliability". United States. doi:10.1109/JPHOTOV.2017.2746682.
@article{osti_1405279,
title = {Defining Threshold Values of Encapsulant and Backsheet Adhesion for PV Module Reliability},
author = {Bosco, Nick and Eafanti, Joshua and Kurtz, Sarah and Tracy, Jared and Dauskardt, Reinhold},
abstractNote = {The width-tapered cantilever beam method is used to quantify the debond energy (adhesion) of encapsulant and backsheet structures of 32 modules collected from the field. The collected population of modules contains both those that have remained intact and those with instances of either or both encapsulant and backsheet delamination. From this survey, initial threshold values (an adhesion value above which a module should remain intact throughout its lifetime) for encapsulant and backsheet interfaces are proposed. For encapsulants this value is ~ 160J/m2 and for backsheets ~ 10J/m2. Here, it is expected that these values will continue to be refined and evolve as the width-tapered cantilever beam method gets adopted by the PV industry, and that they may aid in the future improvement of accelerated lifetime tests and the development of new, low-cost materials.},
doi = {10.1109/JPHOTOV.2017.2746682},
journal = {IEEE Journal of Photovoltaics},
number = 6,
volume = 7,
place = {United States},
year = {Wed Oct 04 00:00:00 EDT 2017},
month = {Wed Oct 04 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on October 4, 2018
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  • The width-tapered cantilever beam method is used to quantify the debond energy (adhesion) of encapsulant and backsheet structures of 27 modules collected from the field. The collected population of modules contains both those that have remained in-tact and those with instances of either or both encapsulant and backsheet delamination. From this survey, initial threshold values (an adhesion value above which a module should remain intact throughout its lifetime) for encapsulant and backsheet interfaces are proposed. For encapsulants this value is about 60 J/m2 and for backsheets about 20 J/m2. It is expected that these values will continue to be refinedmore » and evolve as the width-tapered cantilever beam method becomes adopted by the PV industry, and that they may aid in the future improvement of accelerated lifetime tests and the development of new, low-cost materials.« less
  • MDRC Techniques are used for the detection of the vulnerability in specific regions in a PV module. They can also be useful as quality control tools. PV modules were selected randomly at the factory floor over a sixteen month period. Adequate number of samples were extracted at predetermined locations in the middle, periphery, and bus line regions from a selected cells of each module. Adhesive shear strength was measured during the extraction of the samples. Care was taken to verify that the data was statistically significant. Consistently high values of adhesive strength are desirable in all the regions. There wasmore » a smaller spread of values in the batches with higher adhesive strengths. On the other hand, the data showed wider fluctuations in the batches of lower average values of adhesive shear strength showing that inhomogeneity from one region to other may be leading to overall low values. The techniques were found to be useful for assuring quality. The information may be useful for determining warranty period. {copyright} {ital 1999 American Institute of Physics.}« less
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  • Photovoltaic (PV) module soiling is a growing area of concern for performance and reliability. This paper provides evaluations of the fundamental interactions of dust/soiling particles with several PV module surfaces. The purpose is to investigate the basic mechanisms involving the chemistry, morphology, and resulting particle adhesion to the first photon-incident surface. The evaluation and mapping of the chemistry and composition of single dust particles collected from operating PV module surfaces are presented. The first correlated direct measurements of the adhesive force of individual grains from field-operating collectors on identical PV module glass are reported, including correlations with specific compositions. Specialmore » microscale atomic force microscopy techniques are adapted to determine the force between the particle and the module glass surface. Results are presented for samples under dry and moisture-exposed conditions, confirming the effects of cementation for surfaces having soluble mineral and/or organic concentrations. Additionally, the effects of hydrocarbon fuels on the enhanced bonding of soiling particles to surfaces are determined for samples from urban and highly trafficked regions. Comparisons between glass and dust-mitigating superhydrophobic and superhydrophilic coatings are presented. Potential limitations of this proximal probe technique are discussed in terms of results and initial proof-of-concept experiments.« less