A silicon photovoltaic module converts sunlight energy into electricity applying the photovoltaic effect of the semiconductor. But the performance of PV module is affected by ambient temperature. It is well known that the power and efficiency of PV module usually falls at a rate of -0.5%/degrees C and -0.05%/degrees C, respectively as increase of ambient temperature. In this study, the thermal characteristics of a PV module by change of ambient temperature from -25 degrees C in minimum to 50 degrees C in maximum is investigated through a thermal analysis simulation program. In the end, a simulation method to attach fins to the backside of PV module is discussed. This work shows the comparison of the thermal characteristics between a PV module with and without fins. Crown Copyright (c) 2010 Published by Elsevier B.V. All rights reserved.