Experimental investigation of the shading losses on solar module system performance

Silicon solar panels are commonly used in photovoltaic applications. The voltage produced by individual solar cell is limited to 1 V. Hence, solar cells are connected in series/parallel in order to obtain the desired voltage suitable for power conversion. Therefore, even a very small amount of shading of solar cells/panels in the network affects the overall performance of the module significantly. If the affected panel is wired in series (in a string) with other panels, then the output of all those panels will be affected by the partial/full shading of one panel. To analyze the effect of shading on the overall system performance, we have developed a MATLAB Simulink model to calculate Power vs Voltage (P-V) and Voltage vs Current (V-I) characteristics of solar panel under different shading conditions. The MATLAB model was experimentally validated by investigating the effect of shading using AAA class solar simulator. Simulations and experimental results show that even 20-30% shading of the solar module will result in 30-40% reduction in the power output. This demonstrates the importance of developing MPPT (Maximum Power Point Tracking) algorithms tailored to various situations which can work well in dusty environments and cloudy days. Its affect is of a prime interest to various IPP´s (Independent Power Producers) especially in a large open solar farm.