Model and Analysis of Photovoltaic Array Under Partial Shading

Partial shading makes output voltage-current curve of photovoltaic (PV) array stair-stepping and corresponding power-voltage curve possessing local peak values,so existing conventional PV array model is no more suitable and it is necessary to build a new mathematical model of PV array that is suitable for partial shading condition.Based on engineering model of PV array and combining with series-parallel connection of electric circuit,the PV array under partial shading is analyzed in detail and it is derived theoretically that the mathematical model of PV array under partial shading can be expressed by piecewise function,and experimental verification of this conclusion is performed to prove that the built PV array model can describe the output characteristics of PV array under partial shading well.Using the built model,the operating conditions of concrete PV array under different number of shades,sheltering modes,illumination and temperatures are simulated.Simulation results show that the influences of partial shading on output characteristics of PV array are different and are dependent on different patterns and distributions of PV arrays and different number and distribution of shades as well as temperatures,illumination and sheltering modes.