Title:	Chemical and Morphological Characterization of PVDF Films used for Photovoltaic Backsheets
Author(s):	C. Barretta, E. Helfer, P. Christöfl, A. Macher, M. Bredács, A. Gok, G. Oreski
Keywords:	Polymer Film, Reliability, Durability, Characterisation
Topic:	Photovoltaic Modules and BoS Components
Subtopic:	Materials for PV Modules, Durability, Reliability and Accelerated Testing Methods
Event:	8th World Conference on Photovoltaic Energy Conversion
Session:	3DV.3.33
ISBN:	3-936338-86-8
Price:	0,00 EUR
Document(s):	poster

Abstract/Summary:

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Backsheet materials are key components in photovoltaic (PV) modules because they protect the internal parts from the environmental stresses and provide electrical insulation to the whole structure. In 2019, PVDF-based backsheet accounted for the 64% of the market share and unfortunately in the last years also the amount of crack observations of PVDF-based backsheets in the field in the first 6-10 years of operation increased. The aim of this work is to better understand the chemical and morphological composition of PVDF used in PV backsheets, and to understand which feature is related to crack formation. Seven PVDF films used to produce commercial PVDF-based backsheet were used in this study. The materials were additionally subjected to damp heat (DH) test at 85 °C and 85% of relative humidity for 1000 hours. Changes in chemical structure, morphology, thermal stability and mechanical properties were investigated. The results showed that the PVDF films could be distinguished into three classes according to presence of acrylate based polymer/PVDF blend, presence of fillers, and type of fillers. Additional evidence of post-crystallization phenomena and physical ageing were detected after DH exposure.