Reliability of photovoltaic modules is critical to the longevity of solar panels. Ethylene vinyl acetate (EVA), a semi-crystalline polymer, is a common encapsulant and a critical component in solar panels. After assembly of solar panels, EVA is thermally cured between 140-160 <sup>o</sup>C for ~20 minutes under vacuum and pressure, typically to about ~ 70% gelation for best results. A key challenge to the long term use of solar panels is degradation of the EVA layers following UV exposure. Even with antioxidants, adhesion promoters and UV absorbing additives, efficiency of solar panels is compromised resulting from delamination of layers, corrosion and loss of light transmission. To improve the reliability of the polymer, the concept of a post cross-linking initiated by UV exposure is explored that maintains the integrity of EVA film in solar panels, and possibly mitigate the degradation processes problematic in current solar panels.  Benzophenone was added to commercial EVA films and, following thermal curing, cross-linking of the EVA polymer through UV exposure was studied in different environments: Long-term exposure to ambient sunlight and, a higher intensity 350 nm exposure over 10-90 minutes in a UV chamber for a more controlled environment. The thermal properties of EVA after thermal curing and following UV exposure will be presented.<br/>

Post–UV initiated cross-linking of thermally cured EVA encapsulant in solar panels

2019 Fall National Meeting

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