In this paper, we studied the influence of EVA sheet gel content on photovoltaic module durability. Depending on thermal curing temperature and time during lamination, there are dramatic changes on chemical and physical characteristics. To find the optimum PV module process condition, Glass/EVA/Back Sheet scheme was made. Gel Content, FT-IR spectrum and SEM were used for the detail analysis. From these results, 110℃/6min and 130℃ /4min lamination condition could be suggested for the best one for durable PV module processing. The further analysis is described in the following paper.