Effect of Encapsulant Degradation on Photovoltaic Modules Performances Installed in Different Climates

Abstract

A damage analysis was conducted on photovoltaic modules with identical bill of materials exposed to different climates: Cfb moderate and Af tropical, according to the Köppen-Geiger climate classification. The combination of high temperature, relative humidity, and high ultraviolet (UV) radiation was the cause of severe degradation for the modules exposed to tropical climates (TR), whereas the module exposed to a moderate climate did not experience a significant loss in performance. The modules installed in TR, on the contrary, showed significant power degradation after approximately 8 years of exposure, primarily attributed to acetic acid-related degradation modes. Encapsulant samples were extracted from the selected modules and characterized to determine changes in chemical structure, thermal stability, and consumption of additives and stabilizers. The results of qualitative additive analysis showed that the UV absorber was no longer detectable in the front encapsulant extracted from modules exposed in TR. The consumption of the stabilizers was considered as the main cause of reduction of molar mass. The presence of acetic acid was evident in both electroluminescence images and ion chromatography results. While differential scanning calorimetry successfully detected a reduction in molar mass, thermogravimetric analysis, and infrared spectroscopy proved unsuitable for identifying chain scission phenomena.