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Microstructure changes during failure of PVDF-based photovoltaic backsheets

Published

Author(s)

Stephanie Moffitt, Po-Chang Pan, Lakesha Perry, Michael Kempe, Jared Tracy, Kaushik Choudhury, Xiaohong Gu

Abstract

The backsheet layer of a solar module provides a safety and environmental barrier to the high voltages running through the photovoltaic (PV) cells and electrical contacts within the core of the module. However, in the past decade, backsheet cracking has become one of the most observed failure modes in PV module field surveys. In this work, the degradation of polyvinylidene fluoride (PVDF)-based backsheets is explored. Backsheet samples are either exposed to accelerated laboratory aging (UV light, heat, and moisture) or collected from the field. Fourier transform infrared and Raman spectroscopy, fragmentation testing, atomic force and scanning electron microscopy, and small-angle neutron scattering are combined to develop an understanding of how chemistry and microstructure evolve during aging. Chemical degradation, surface pitting, polymer phase changes, and anisotropic polymer domains are all observed in aged backsheet samples. The results provide insight into the degradation mechanisms that lead to cracking and field failure of PVDF-based backsheets. The comparison of aged PVDF-based backsheets helps to lay the groundwork for limiting polymer-based failure modes in PV modules.
Citation
Progress in Photovoltaics

Keywords

backsheets, accelerated aging, phase-change, polymer degradation

Citation

Moffitt, S. , Pan, P. , Perry, L. , Kempe, M. , Tracy, J. , Choudhury, K. and Gu, X. (2022), Microstructure changes during failure of PVDF-based photovoltaic backsheets, Progress in Photovoltaics, [online], https://doi.org/10.1002/pip.3605, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=933067 (Accessed November 29, 2022)
Created July 21, 2022, Updated August 30, 2022