The aging behavior and service time estimation of photovoltaic backsheets based on artificially accelerated aging and outdoor aging

Abstract

The aging of photovoltaic (PV) backsheets under the environmental stress severely threatens the security and service life of PV modules. To ensure the safety and reliability of PV backsheets, attempts at linking the indoor accelerating aging and outdoor exposure results and at estimating the service life in their intended service environments have been made. Herein, we present time-dependent measurements of the physical and chemical degradation properties of fluorocarbon-coated photovoltaic backsheets (CPC backsheets) exposed to either indoor multi-factor accelerated aging conditions or outdoor exposure environments. The selected outdoor weathering sites--Wuzhong (WZ), Jinchang (JC), and Changshu (CS), China--were chosen to represent the typical climate conditions of Temperate Continental semi-arid Climate, Temperate Continental Arid Climate, and Subtropical Monsoon Oceanic Climate, respectively. The chemical and microstructural degradation of CPC backsheets was quantified by ATR-FTIR spectroscopies and thermal analyses. The results indicate that the degradation mechanisms for CPC backsheets exposed to outdoor environments are similar to those exposed to indoor multi-factor accelerated aging conditions. Consequently, a reaction-controlled kinetics model has been proposed to quantitatively estimate the decline in mechanical properties. This model has been validated using elongation at break data obtained from multi-factor accelerated aging tests. Furthermore, utilizing this model, the service life of CPC backsheets exposed to WZ, JC, and CS has been successfully assessed with limited field exposure data. This study unveils the aging mechanism of PV backsheets and establishes a straightforward and reliable model for predicting the long-term performance of PV backsheets under diverse outdoor serving conditions.