Submodule-Based Modeling and Simulation of a Series-Parallel Photovoltaic Array under Mismatch Conditions

This paper presents a simple and theoretically sound submodule-based model to simulate the characteristics of a photovoltaic (PV) array with a series-parallel configuration. The proposed model can describe the behavior of bypass diodes as well as the full PV array characteristics under varying irradiance and temperature conditions. Rather than using the nonlinear system of equations solved with a Jacobian matrix, separate equations are employed to model the submodule-based PV array and solved by an easy-to-implement bisection search method. Consequently, the output current of the PV array can be readily determined when its output voltage, the irradiance levels, and temperature values of all submodules are given. The robustness and calculation efficiency of the proposed computational method are analyzed. Some test examples allow us to exhibit the acceptable accuracy of the proposed model. Special attention of this work is paid to the simulation approach to evaluate the electrical mismatch losses in large-scale PV arrays with nonuniform aging after several years of field operation and exposure.