Design of I-V Scanner to Analyze the Effects of Partial Shading due to Soiling and Bird-dropping on PV Panels

In-field photovoltaic (PV) panel’s performance degrades with time due to soiling. Although this degradation is expected to be revered after cleaning, many cleaning techniques are inefficient close to the panel edges creating non-uniform shading. Partial or non-uniform shading on the PV module non-linearly decreases output power, degrades panel lifetimes, and therefore can be detrimental to the PV farm economics. In this paper, we have designed a simple I-V scanner to analyze the changes in the I-V and P-V characteristics curves of the PV panel. We use the I-V scanner to study and analyze partial shading conditions which emulate bird-droppings and non-uniformly distributed soiling accumulation on the surface of PV module or panel. Finally, we summarize the results through the maximum power point (MPP) of the PV panels under different shading conditions. We explain how panel-edge soiling bands (after cleaning) or bird droppings suppress panel-array output—these should therefore be carefully addressed in solar farms for optimal operation.