Experimental evaluation of the discoloration effect on PV-modules performance drop

The objective of this paper is to measure and evaluate the degradation impact on a photovoltaic (PV) module exposed for almost two years under Moroccan climate. This degradation is a discoloration spot observed above the module's junction box. For this purpose, the drop of the module's electrical performances has been firstly measured using the I-V tracer PVPM1000X and compared with the initial values given by the manufacturer. Afterwards, and in order to measure the direct effect of the detected discoloration on the power production, comparison between the outputs of the affected module and another one with the same characteristics (taken as reference) has been done. Results show that the module's degradation rate (from the initial state) is of 7.56 %/year. Moreover, the power difference between the affected modules and the one taken as reference was found to be of 13.2 watts in average. Generally, this difference is directly linked to the detected discoloration and it represents a power drop of 5.28% from the module's initial capacity.