Abstract: The unit may be mounted either in a window or between the studs of a building that is to be supplied with solar heat. The bottom of the unit extends farther from the building than the top and is wider than the top of the unit such that the transparent side away from the building has an arcuate form and is gradually flared outwardly in a downward direction to increase the exposure to the sun during the day. A plurality of absorptive tubes within the unit are slanted from the upper portion of the unit downwardly and outwardly to the front arcuate portion of the bottom. Openings between the unit and the building are provided for air flow, and a thermostatically controlled fan is mounted in one of the openings. A baffle is mounted between the absorptive tubes and the mounting side of the solar heating unit, and the surfaces of the baffle and the absorptive tubes are painted a dull black for absorbing heat transmitted from the sun through the transparent, slanting side.