Aging Characteristics Of Photovoltaic Insulating Backsheet Under The Synergism Of Multi-Factor

With the increasing installed capacity of renewable energy,photovoltaic power generation will play a key role in the clean transformation of China’s energy structure in the future.As the core component of photovoltaic module,the service life of the insulating backsheet plays a vital role in the long-term use and reliability of the modules.However,the backsheet is susceptible to various environmental stresses in the outdoors,which accelerates the aging of progress and reduces the service life of the backsheet,making it impossible to achieve the expected service life of 20 years.At present,the traditional single-factor aging models are difficult to realize the comprehensive evaluation of the life of insulating backsheet.Therefore,it is of great theoretical value and practical significance to study the aging mechanism under the synergistic effect of multiple factors and establish the multi-factor aging model for predicting the lifetime of insulating materials.Based on the study of aging characteristics and life model of photovoltaic insulating backsheet,this paper designed and built the aging model of single factor and the sequential aging model of multi-factor.Through accelerated aging tests under different stresses,the elongation at break was taken as the aging characteristic value.Combined with fitting and regression analysis,the aging model of single factor and the sequential aging model of radiation-thermal multi-factor based on degradation rate were established to study the effect of radiation on the lifetime of the insulating backsheet.The results showed that the degradation rate increased from 0.00042h-1 to 0.003h-1 and the incubation time decreased from 264h to 27h with the increase of temperature of the backsheet irradiated for 1000h.Compared with the thermal aging model,radiation accelerated the aging of the backsheet,which made the elongation at break decrease faster,and reached the end of lifetime earlier.In order to relate the change of macroscopic properties with the microstructure and physical mechanism during the aging process,the aging characteristics of backsheet under the synergistic effect of multiple stresses were further studied.In this paper,based on the comprehensive characterization techniques of chemistry,electricity and mechanics,Fourier infrared spectroscopy,differential scanning calorimetry,mechanical properties,partial discharge and voltage breakdown of the samples after different stresses were tested.The results showed that under the comprehensive action of radiation and temperature,the performance of the backsheet decayed obviously.The degradation of the backsheet was mainly presented in the change of chemical group and the increase of crystallinity.Furthermore,the above-mentioned changes could result in the decrease of mechanical and insulation properties.In summary,the elongation at break was taken as the aging characteristic value to establish the aging model of single factor and the sequential aging model of multi-factor based on degradation rate in this paper.In addition,the comprehensive characterization of the backsheet after aging was carried out from the aspects of chemistry,electricity and mechanics,which was of great significance for predicting the remaining life and guiding the insulation design.