The thermal recovery effect from the light-induced degradation under the sunlight is experimentally investigated on the amorphous silicon photovoltaic module (a-Si PV module) for installing directly to the roof flames of wooden houses. To enhance the recovery effect, the heat-insulating material is attached to the back side of the module for increasing the module temperature under the sunlight: the heat-insulated module. The generated power from the heat-insulated module is compared with that from the normal module (without the heat-insulating material) for 2 yr, and it has been cleared that the generated power normalized at 25 degrees C from the heat-insulated module is approximately 7.3% higher than that from the normal one with the average temperature increase of 4.2 degrees C under the sunlight.