Field-Aged Glass/Backsheet and Glass/Glass PV Modules: Encapsulant Degradation Comparison
Abstract
Ethylene vinyl acetate (EVA) is the predominant encapsulant in crystalline-silicon photovoltaic (PV) modules; however, its degradation is a subject of major concern, which causes significant power loss under field conditions. This article presents a comparison of EVA degradation in field-aged PV modules with glass/backsheet (G/B) and glass/glass (G/G) architectures. Modulelevel characterization included UV fluorescence imaging and I-V measurements. Material analytical techniques, including colorimetry, differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, and Raman spectroscopy, were performed to correlate the module performance parameters with EVA material properties. An intense EVA discoloration in G/G modules was observed, which was corroborated by higher module Isc and Pmax degradation rates compared with its counterpart G/B modules. Higher power degradation was accompanied by a significant increase in EVA crosslinking, vinyl acetate content, yellowness index, and presence of functional groups containing unsaturated moieties that are linked to degradation products of photothermal reaction, and a higher decrease in the degree of crystallinity. The absence of a polymeric backsheet in hermetically sealed G/G modules, which restricts photobleaching and enhances the entrapment of volatile acetic acid and other degradation by-products, plays a major role in causing higher EVA degradation in G/G modules. This article concludes that EVA mightmore »
- Publication Date:
- Research Org.:
- Arizona State Univ., Mesa, AZ (United States)
- Sponsoring Org.:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Solar Energy Technologies Office
- OSTI Identifier:
- 1799529
- Grant/Contract Number:
- EE0008565
- Resource Type:
- Accepted Manuscript
- Journal Name:
- IEEE Journal of Photovoltaics
- Additional Journal Information:
- Journal Volume: 10; Journal Issue: 2; Journal ID: ISSN 2156-3381
- Publisher:
- IEEE
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 14 SOLAR ENERGY
Citation Formats
Patel, Aesha Parimalbhai, Sinha, Archana, and Tamizhmani, Govindasamy. Field-Aged Glass/Backsheet and Glass/Glass PV Modules: Encapsulant Degradation Comparison. United States: N. p., 2019.
Web. doi:10.1109/jphotov.2019.2958516.
Patel, Aesha Parimalbhai, Sinha, Archana, & Tamizhmani, Govindasamy. Field-Aged Glass/Backsheet and Glass/Glass PV Modules: Encapsulant Degradation Comparison. United States. https://doi.org/10.1109/jphotov.2019.2958516
Patel, Aesha Parimalbhai, Sinha, Archana, and Tamizhmani, Govindasamy. Fri .
"Field-Aged Glass/Backsheet and Glass/Glass PV Modules: Encapsulant Degradation Comparison". United States. https://doi.org/10.1109/jphotov.2019.2958516. https://www.osti.gov/servlets/purl/1799529.
@article{osti_1799529,
title = {Field-Aged Glass/Backsheet and Glass/Glass PV Modules: Encapsulant Degradation Comparison},
author = {Patel, Aesha Parimalbhai and Sinha, Archana and Tamizhmani, Govindasamy},
abstractNote = {Ethylene vinyl acetate (EVA) is the predominant encapsulant in crystalline-silicon photovoltaic (PV) modules; however, its degradation is a subject of major concern, which causes significant power loss under field conditions. This article presents a comparison of EVA degradation in field-aged PV modules with glass/backsheet (G/B) and glass/glass (G/G) architectures. Modulelevel characterization included UV fluorescence imaging and I-V measurements. Material analytical techniques, including colorimetry, differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, and Raman spectroscopy, were performed to correlate the module performance parameters with EVA material properties. An intense EVA discoloration in G/G modules was observed, which was corroborated by higher module Isc and Pmax degradation rates compared with its counterpart G/B modules. Higher power degradation was accompanied by a significant increase in EVA crosslinking, vinyl acetate content, yellowness index, and presence of functional groups containing unsaturated moieties that are linked to degradation products of photothermal reaction, and a higher decrease in the degree of crystallinity. The absence of a polymeric backsheet in hermetically sealed G/G modules, which restricts photobleaching and enhances the entrapment of volatile acetic acid and other degradation by-products, plays a major role in causing higher EVA degradation in G/G modules. This article concludes that EVA might have been a good choice of an encapsulant for the G/B modules over the decades, but it may prove to be an inappropriate choice for the G/G modules because of potential degassing, corrosion, and/or discoloration issues. Ionomers or polyester-based encapsulants like polyolefins could be best suited for G/G modules as it appears to be a current trend in the industry.},
doi = {10.1109/jphotov.2019.2958516},
journal = {IEEE Journal of Photovoltaics},
number = 2,
volume = 10,
place = {United States},
year = {Fri Dec 27 00:00:00 EST 2019},
month = {Fri Dec 27 00:00:00 EST 2019}
}
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