One of the common failures in photovoltaic modules is the degradation of the ethylene-vinyl acetate (EVA) encapsulant due to prolonged ultraviolet exposure and other environmental stress factors, such as temperature and humidity. Experimental studies have shown that significant reduction in the optical transmission due to EVA degradation leads to loss in the available power by more than 50%. In this article, a novel approach to predict the early degradation of EVA encapsulant is proposed by correlating EVA degradation with short-circuit current ( I _SC ). An electrical circuit simulator, simulation program with integrated circuit emphasis (SPICE), is used to evaluate the short-circuit current obtained under varying optical transmission caused by EVA discoloration. The simulation follows three steps: simulation of the transmitted solar spectrum; simulation of the spectral short-circuit current density; and simulation of the current-voltage ( I–V ) curve to obtain short-circuit current ( I _SC ), maximum power output ( P _max ), open-circuit voltage ( V _OC ) and fill factor. Results show that the reduction in short-circuit current due to EVA degradation differs from the reductions expected due to a spectrally-uniform reduction of intensity of the solar irradiance. Both types of variation are linear, however, the slope due to EVA degradation is larger than the slope obtained for normal intensity variations in the solar irradiance. This model, when applied in conjunction with solar irradiance measurements, can predict early onset of EVA encapsulant failure, thereby enabling preventative measures to be taken.

中文翻译：

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通过短路电流测量预测光伏模块中的早期 EVA 降解

光伏组件的常见故障之一是由于长时间暴露在紫外线下和其他环境压力因素（如温度和湿度）导致乙烯-醋酸乙烯酯 (EVA) 密封剂降解。实验研究表明，由于 EVA 降解导致光传输的显着降低导致可用功率损失 50% 以上。在本文中，通过将 EVA 降解与短路电流相关联，提出了一种预测 EVA 密封剂早期降解的新方法。 我 _SC ）。电路模拟器，集成电路重点模拟程序（SPICE），用于评估在由EVA变色引起的不同光传输下获得的短路电流。模拟分为三个步骤： 透射太阳光谱的模拟；频谱短路电流密度的模拟；和电流电压模拟（ I–V ) 曲线获得短路电流 ( I _SC ), 最大功率输出 ( P _max ), 开路电压 ( V _OC ) 和填充因子。结果表明，由于 EVA 降解引起的短路电流减少与由于太阳辐照强度在光谱上均匀减少而导致的预期减少不同。两种类型的变化都是线性的，然而，由于 EVA 降解产生的斜率大于太阳辐照度的正常强度变化所获得的斜率。该模型与太阳辐照度测量结合使用时，可以预测 EVA 密封剂失效的早期发生，从而能够采取预防措施。