Degradation of Crystalline Si‐Based Solar Modules With Varying Material Combinations—Part I: Encapsulant Degradation

ABSTRACT This work is the first part of three studies dealing with the degradation of crystalline Si‐based solar modules depending on the chosen material combination, whereby the focus of this work is on encapsulant degradation. Within the paper, solar modules based on ethylene‐vinyl acetate (EVA) copolymer encapsulant and polyolefin elastomer (POE) encapsulant with different rear side encapsulations were artificially aged with UV irradiation (76.6 W/m 2 between 280 and 380 nm) in combination with 60% relative humidity at 85°C. In situ moisture measurements and simulations of oxygen diffusion were used to show how stressors are distributed in the module. Additive and polymer degradation was analyzed by the Fourier transform infrared spectroscopy (FTIR), Orbitrap mass spectrometry, and electron paramagnetic resonance (EPR). This approach made it possible to determine the degradation of the encapsulants in a spatially resolved manner depending on the presence of stressors and the consumption of additives. The findings reveal that degradation is heavily influenced by the microclimate within the module, which itself is affected by the material combinations used. It is shown that oxygen has a major influence on the degradation of POE, as it is essential for the formation of hydroperoxides. Furthermore, it becomes clear that EVA does not necessarily have to be inferior to the novel POE encapsulants if it is combined with the right rear side encapsulation.