A solar cell module (206,404) is provided at the position of a heat collecting plate (405) inside a heat collector (200,400), at the position of its window member (204,403) or at the position of its bottom plate. With such constitution, a hybrid system can be achieved in which the hot air can be led into a house while maintaining the performance of solar cells making use of amorphous silicon semiconductors. In the case where solar cells are provided at the position of the heat collecting plate, a resin used as a filler has so high a thermal resistance that the heat conduction to the air may be insufficient to make it impossible to obtain hot air having a sufficiently high temperature. To solve this problem, the solar cell module (206,404) is made to have a smaller thermal resistance on the non-light-receiving side than the thermal resistance on the light-receiving side.