Abstract： In order to investigate the temperature of amorphous silicon photovoltaic panel (a-Si PV) under sunny and cloudy conditions, a thermal model was developed based on the total energy balance on the control volume. In the differential equation, the corresponding short wave radiation, long wave radiation, convection and generated power were determined, respectively. And then, this equation was solved by a newly-developed program. Besides, an experimental mockup was designed to get the experimental data for the verification of the numerical results. The measured results show that the effect of solar irradiance on temperature is much more significant than that of the installation angles and ambient temperature, and that the maximum temperature variation under sunny condition is greater than that under cloudy condition. The comparative analysis shows that this model could correctly predict the temperature of the a-Si PV under sunny and cloudy conditions. The maximum difference is 3.9 °C. The acceptable reasons are the solar irradiance with strong fluctuation under cloudy condition and the PV thermal response time effects caused by the thermal mass of the PV materials. In summary, this model could consider most of the variables influencing the temperature of the PV and get the precise temperature variation of the a-Si PV under sunny and cloudy conditions.