Degradations of an encapsulant of a random copolymer of ethylene and vinyl acetate (EVA), in long-term outdoor-exposed (OE) crystalline silicon (c-Si) photovoltaic (PV) modules were investigated by Raman and Fourier transform-infrared (FT-IR) spectroscopy measurements. Two predominant chemical and photochemical degradations, discoloration (yellow-browning) and formation of acetic acid (AcOH), were observed in EVA encapsulants in c-Si PV modules exposed outdoors for approximately 27 years in Japan (Kirishima module). The yellow-browning of the encapsulants was suggested to be due to reaction of additives, such as UV absorbers that were incorporated in the encapsulants, because no marked degradation of EVA itself was observed in the FT-IR absorption spectrum. Contrastingly, the absorption intensity of C = O of the colorless EVA in the Kirishima module decreased to 70%, which was similar to that for the encapsulant in a damp-heat-tested (DHT) module at 85 °C with 85% relative humidity for 4000 h (68%), suggesting that AcOH was formed from EVA. The degradation mechanisms of the EVA encapsulants in long-term OE and DHT c-Si PV modules were explored by spectroscopy and other analyses.

通过拉曼和傅里叶变换红外（FT）研究了长期暴露于室外（OE）的晶体硅（c-Si）光伏（PV）模块中乙烯和乙酸乙烯酯（EVA）的无规共聚物的密封剂的降解情况-IR）光谱测量。在日本暴露在户外约27年的c-Si PV组件（雾岛组件）中，在EVA密封剂中观察到两个主要的化学和光化学降解，变色（黄褐色）和乙酸（AcOH）形成。密封剂的黄褐色被认为是由于添加剂的反应，例如掺入密封剂中的紫外线吸收剂，因为在FT-IR吸收光谱中未观察到EVA本身的明显降解。相反，雾岛组件中无色EVA的C = O的吸收强度降低至70％，这与在85°C，相对湿度为85％的湿热测试（DHT）模块中的密封剂在4000°C下的吸收强度相似h（68％），表明AcOH由EVA形成。通过光谱学和其他分析研究了长期OE和DHT c-Si PV组件中EVA密封剂的降解机理。