Experimental investigation of the effect of partial shading on photovoltaic performance

Partial shading of a photovoltaic (PV) installation has an inconsistent impact on power production. This study investigates the effect of partial shading on PV performance. The experiments were carried out with a 90-W PV module under both variable and constant irradiations with shaded area increased from 0 to 80% to observe the effect of variable solar radiation at certain shading points. The effect of shading under irradiation levels from 300 to 800 W/m2 was investigated. At a 600 W/m2 irradiation level, the shading impact factor was 1.25 with a 25% shading, while at 75% shading the impact factor decreased to 0.86. Results also show that for every 100 W/m2 increase in irradiation level, the electrical power output was enhanced by 3.89, 3.37, 2.27, and 2.02 W at 0, 25, 50, and 75% shading, respectively. The efficiency level was increased by 0.29, 0.27, 0.25, and 0.22% at 0, 25, 50, and 75% shading, respectively. Increasing the shaded area by 10% causes a 12.41 W drop in power output and a 2.3% drop in electrical efficiency. Partial shading not only deteriorates the PV performance, but also causes long-term degradation of the module.