Assuming that the photocurrent is much larger than the diode reverse saturation current,shunt resistance is infinite and diode reverse saturation current is independent of light intensity,a performance prediction model of photovoltaic module under different operating conditions was proposed and a simulation system was built by using Matlab/Simulink programs.Through the comparison between computer simulations and experimental data for mono/poly crystalline silicon photovoltaic modules,it showed that the proposed model can accurately predict the photovoltaic modules output characteristics at different light intensities and temperatures,and the relative prediction error precisions were all below 6%.The results also reveal that temperature change has a greater impact on modules performance prediction than the light intensity,and it is harder to predict module performance of polycrystalline silicon than that of mono crystalline silicon.Moreover,the prediction results of photovoltaic modules performance in natural environment showed that the output characteristics of the modules are mainly determined by light intensity rather than by temperature.it is found that the output voltage of the modules should be varied when conditions of light intensities and temperatures change,in order to achieve the maximum output power.