A new approach for modeling photovoltaic modules based on difference equation

A modeling method of photovoltaic (PV) module based on difference equation is proposed. Firstly, the derivative of the I-V characteristic curve is solved based on the extracted parameters. Then, the I-V characteristic curve of PV module is obtained using the difference equation combined with the photocurrent by recursive algorithm. This modeling method effectively avoids the need of iterative algorithm. In addition, when the temperature of PV module is constant, another method is proposed to obtain the I-V characteristic curve under any solar irradiance by using the I-V characteristic curves when the solar irradiance is 200 and 1000 W/m(2) respectively. In this case, only a single model parameter is required. The parameters of the model are extracted by a numerical method. Firstly, the region where each parameter affects the I-V characteristic curve is analyzed. And each parameter is given an initial value according to the analytic expression. Then, according to the criterion of the coefficient of determination, the values of each parameter are dynamically adjusted to achieve the optimal value. This method avoids such disadvantages as long running time and difficult convergence. Finally, the effectiveness of the two new models and the corresponding parameter extraction method are verified by simulation. (c) 2020 Elsevier Ltd. All rights reserved.