PURPOSE: To provide a heat collector, which is excellent in its electric insulating performance and capable of facilitating fixing of solar batteries, by forming projections for fixing solar batteries on the upper side of a heat collecting panel, and forming passages for a heat collecting medium on the lower side of the heat collecting panel.

CONSTITUTION: A heat collecting panel 11 is formed on its upper side with projections 8 for fixing solar batteries 9 and it is formed on its lower side with passages 10 for a heat collecting medium. The head portion of each projection 8 is shaped to have a semicircular cross section and made greater than the shank portion so that the solar batteries 9 can be clamped in place by the head portion of the projection 8. Therefore, it is enabled to facilitate fixing of the solar batteries and to cool them effectively.