Improvement in the reliability of photovoltaic mini-modules through modifying the structural composition of EVA encapsulant

Abstract

The photovoltaic (PV) module manufacturers use ethylene vinyl acetate that contains 28 to 33% by weight vinyl acetate (VA) for the encapsulation application. However, it has been found in various field surveys that EVA degrades during its operation in the field. The resilience of ethylene vinyl acetate against environmental stressors can be enhanced by optimising its vinyl acetate (VA) content as has been seen in the few studies done on free-standing EVA films. However, no such comparative study has been carried out on EVA films placed in a module mimicking the actual structure of a PV module. Therefore, in this work EVA films containing 18, 24 and 33% VA content by weight are prepared with the necessary additives to fabricate mini-modules. These mini-modules have been subjected to damp-heat (DH) ageing for 1000 h at 85 °C temperature and 85% relative humidity (RH) according to IEC 61,215 standard. The power output, adhesion strength and volume resistivity reduce and YI increases for the modules containing EVA33 after ageing. However, no significant changes are observed for the above-mentioned properties for the modules containing EVA24 and EVA18. This study presents findings of 1000 h of DH ageing as per IEC standards for mini-modules containing different EVA films and observed that the films of EVA18 and EVA24 are resilient compared to EVA33. Moreover, the findings on mini-modules have a few differences with prior studies done on free-standing EVA the films.