Abstract: The panel for converting solar energy to sensible heat of a working fluid comprises a thermally-insulated and impervious base member overlayed with and spaced from a solar-collecting member or collector. The collector is in turn overlayed with and spaced from a pair of mutually spaced impervious films which are essentially transparent to incident solar radiation and substantially opaque to radiation emitted by the collector. The solar-collecting member consists of a thermally-insulating porous matrix substance and of a second substance affixed thereto. The second substance is in divided and substantially discrete form. The second substance exhibits a high degree of absorptivity for solar radiation and low emissivity for long wave radiation. The working fluid to be heated is admitted to a chamber underneath the solar-collecting member. The working fluid has a pressure sufficient to cause it to percolate through the collector.