MATLAB-based modeling of shading effects in photovoltaic arrays

This paper presents a MATLAB-based modeling and simulation scheme suitable for studying the I-V and P-V characteristics of a PV under a nonuniform insolation due to partial shading. In the first, part a solar cell block is available in MATLAB®/Similink, which was used with many other blocks to plot I-V and P-V characteristics under variations of parameters considering one parameter variation at a time. The effect of variation of parameters such as series resistance, Rs, shunt resistance Rsh, diode parameter: diode saturation current, I0, could be seen on the characteristics of a solar cell. Effect of two environmental parameters of temperature and irradiance variations could also be observed from simulated characteristics. In the second part, the performance of a photovoltaic (PV) array is affected by temperature, solar insolation, shading. Often, the PV arrays get shadowed, completely or partially, by the passing clouds neighboring buildings, towers or by trees, etc. The situation is of a particular interest in a case of the large PV power plants. In the case of the shading the characteristics of the PV module are more complex with the several peak values. Under such conditions, it is very difficult to determine the maximum power point (MPP). Finally, MATLAB-programmed modeling and simulation of photovoltaic systems is presented here, by focusing on the effects of partial shading on the output of the photovoltaic (PV) systems. The proposed model facilitates simulating the dynamic performances of PV-based power systems and also has been validated by means of simulation study.