Visual Degradation in Field-Aged Crystalline Silicon PV Modules in India and Correlation With Electrical Degradation

This paper presents the analysis of visual degradation data collected during an All-India Survey of Photovoltaic Module Degradation conducted in 2013, in which 57 crystalline silicon modules were inspected in the five different climatic zones of India. Analysis of the data indicates that the highest percentage of modules suffered discoloration in the Hot and Dry climatic zone, with the Hot and Humid zone coming in second in the list. A higher percentage of modules have suffered corrosion in the Hot and Humid zone, as compared with other zones. The modules installed in the Cold climate suffered the least degradation. Both discoloration and corrosion have been seen in modules across all age groups, even in some of the modules installed less than five years ago. On the other hand, delamination and backsheet degradation have been seen only in modules more than a decade old. The visual degradation data have been correlated with the electrical performance data and reaffirm the direct relation between encapsulant discoloration and reduction in short-circuit current and output power, as well as that of series resistance with metal corrosion.