I. Introduction
The socioeconomic progress of a society continues to depend heavily on energy. With rising oil prices and the negative effects of burning fossil fuels on the environment, it becomes more challenging [1]. There is currently enough flexibility and reliability provided by diverse renewable energy sources and technological advancements to lessen the energy deficit brought on by the rise in demand [2]. In the market for renewable energy, photovoltaic energy is currently a major player [3]. A PV system can be effective for a modest energy need only if the installation is adjusted and maintained. Understanding the longevity and dependability of such a system depends on aging factors, such as hotspots, discoloration, micro-cracks, delamination, etc [4]. Among them, discoloration is an important factor that starts the aging process. Discoloration increases the power reduction, mainly the current decreases, which increases the mismatch power losses in the array modules. Consequently, mismatch power loss increases the discoloration and hotspots. In the outdoor exposure of PV array modules, different types of discoloration can occur. Fig. 1 shows the different discolorations due to environmental effects [5].
Discoloration effects on photovoltaic modules