The investigation of snail trails in photovoltaic modules

The so-called snail trails have caused enormous concerns. Many investigators are in a puzzle about the matter. In this paper we show that silver nanoparticles accumulating within the encapsulation foil cause the brownish discoloration. The source of silver is from silver phosphate impurities in EVA. The driving force accumulating the silver ions is offered by electric field when the solar cell operating outside and certain additives of encapsulation would react with silver ions to create darkened silver nanoparticles. Finally, we show here the effect of this phenomenon on the output power and reliability of photovoltaic power plant.