Effect of Partial Shading on the Performance of Solar PV Module and Impact of Bypass Diode in Performance Enhancement

Abstract

The solar PV Module yields optimum power under Standard Testing Conditions (STC) and hence generates the standard I-V characteristic curve. But in practical cases, this power is reduced due to various environmental effects. One of the main factors that is directly responsible for this degradation of output power is partial shading. Partially shaded cells produce less current than other normal cells exposed to sunlight and behave like a reverse biased p-n junction. As a result, it dissipates power instead of generating and gets heated. Consequently, hotspots are generated which results in reduced open circuit voltage. Therefore, the solar PV module produces less output power than it is supposed to. This paper investigates the temperature gradient that exists between a normally exposed cell and a shaded cell and the degradation in output power caused by the partial shading on the solar PV module. For comparative analysis, two identical PV panels have been taken with one of the panels being shaded partially. Different experimental data has been analyzed through PSpice software to notice how partial shading affects the solar PV panel. Also, PSpice simulation has been done to distinguish the impact of bypass diode in terms of PV output improvement. The phenomenon has also been realized by using a thermal camera and the result has been verified experimentally.