Experimental Determination of Diffusivity of Backsheet and EVA for Silicon Photovoltaic Modules

Abstract

Silicon photovoltaic (PV) modules have a high susceptibility to moisture ingression. The impact of moisture is such that it delaminates the ethylene vinyl acetate (EVA) layer and short-circuits the PV modules by degrading the silver paste at the contacts of the solar cells. In this paper, experimental determination of the flow of moisture in silicon PV modules using SHT25 humidity and temperature sensors has been carried out. For analysis, three configurations have been proposed viz. backsheet-printed circuit board with sensor (PCB)- EVA-glass, EVA-PCB-glass, and backsheet-EVA-PCB-EVA-glass. The obtained experimental results were fitted with the analytical equations to determine the diffusivity of both EVA and backsheet materials. The obtained diffusivity of EVA is 120 times that of the backsheet indicating that diffusion through EVA is an instantaneous process.