Research on electrical ageing characteristic of flexible photovoltaic insulating backsheet after ultraviolet radiation

Focusing on the climate change and environmental pollution, the development and application of renewable energy increasingly obtain more attentions, particularly in solar energy. Nevertheless, PV modules are susceptible to ultraviolet (UV) irradiation and electric field, which cause the decrease of the actual service time of PV modules. Here, the electrical aging characteristics of PV insulating encapsulant after UV irradiation are studied. The changes in the surface morphology and functional groups of polyimides (PI) substrate after UV irradiation and partial discharge (PD) are observed by optical microscopy, atomic force microscopy (AFM), and infrared spectrum, respectively. From the results, compared with the untreated PI, surface topography and molecular structure of PI after UV irradiation for 96 hours have slight change; meanwhile, after discharge for 10 hours, the average surface roughness (Ra) of PI increases from 1.89 nm to 114 nm compared with the PI after UV irradiation, and - CH3 around 2981 cm(-1) has emerged. These findings provide significant information for evaluating the degradation performance of PV encapsulant, and even provide important reference to develop PV encapsulant with excellent performance.