Abstract: A solar collector comprising a collector frame surrounding a transparent collector pane, the frame being mounted to the frame of an existing window inside a building, a plurality of narrow heat sinks fixed to opposite sides of the frame containing solar energy absorbing and retaining means, the heat sinks being spaced so as to allow significant amounts of solar illumination incident on the existing window to pass through the collector pane into the building, a lower port passing through the solar collector and located adjacent the bottom of the collector and an upper port passing through the solar collector adjacent the top of the collector, whereby air from the building can pass through the lower port into a space between the existing window and the collector pane, and out the upper port into the building, thereby heating the interior of the building.