Abstract: Based on the forward and reverse output characteristics of solar cells,the output characteristic model of the photovoltaic module is established. Aiming at the multi-peak output characteristics under shading patterns,this paper presents a calculation method of model parameters to study the influence of different shading patterns on I-V characteristic curve and model parameters. Through simulation and experiment,this paper analyzes the influence law of model parameters affected by the changes of shaded light intensity and number of the shaded cells in unit of module. The results show that the calculated results of the model parameters and the I-V characteristic curve obtained based on the model parameters have high accuracy;the module output characteristic model and parameter calculation method have a good engineering application prospect for fault diagnosis of PV modules and arrays.