The Materials Degradation in Encapsulants for Application in Glass/Glass PV Modules After Accelerated Aging

This work compares material properties of various encapsulant resins and formulations for application in glass/glass PV modules. UV weathering resulted in encapsulant discoloration and loss of optical transmittance through the coupons. This was accompanied with chemical degradation of the encapsulant, in particular at the center of the coupon. Damp heat weathering led to temporary moisture trapping within the glass/glass coupons and changes in polymer crystallinity resulting from annealing at elevated chamber temperatures, but negligible degradation of the chemistry of the encapsulants. Sequential weathering resulted in similar chemical degradation as in the UV weathering, but coupons experienced greater loss in transmittance. Out of the studied set of encapsulant types and formulations, POE encapsulants showed greater durability compared to EV As and TPOs. A change in crystallinity was observed for the TPOs that may explain the evolution of optical haze observed for those encapsulants.