Abstract: An efficient solar collector that uses a collector panel formed of strips similar to conventional aluminum siding includes air distribution channels along opposite edges of the collector panel. These air distribution channels are formed of enlarged collector panel strips and form headers. Openings are formed through the wall on which the siding is mounted adjacent each of these channels so air from the interior of the building may flow through one or more lower openings into one of the channels, then through the space between the exterior side of the wall and the panel into the other channel, and through the other openings to return to the interior of the building. The air is heated indirectly by the solar radiation impinging on the collector panel as the air flows through the space between the wall and the panel. To increase the efficiency of the collector, a blower can be installed in one of the openings to increase the air flow through the collector.