Control of moisture ingress into photovoltaic modules

During long-term exposure of photovoltaic modules to environmental stress, the ingress of water into the module is correlated with decreased performance. By using diffusivity measurements for water through encapsulants such as ethylene vinyl acetate (EVA), we have modeled moisture ingress using a finite-element analysis with atmospheric data from various locations such as Miami, Florida. This analysis shows that because of the high diffusivity of EVA, even an impermeable glass back-sheet alone is incapable of preventing significant moisture ingress from the edges for a 20-year lifecycle. This result has led us to investigate ways to protect module from the moisture through the use of different encapsulating chemistries and materials.