The present invention provides a solar heating system which is particularly suited for use in a building, such as a greenhouse, having walls defining an enclosed interior with at least one of the walls including a light transmissive area for admitting light into the interior of the building. In accordance with the invention a solar heat collector is positioned underlying the light transmissive area of the building wall, with the collector comprising a plurality of elongate radiation absorptive heat conductive elements for receiving solar radiation and being heated thereby. The heat conductive elements extend longitudinally downwardly and are positioned in laterally spaced relation from one another for admitting light therebetween into the building while also serving for partially shading the interior of the building. A stream of heat transfer liquid is directed downwardly in contact with the heat conductive elements for transferring heat therefrom, and a conduit is provided for receiving the heated liquid as it flows from the heat conductive elements and for directing the heating liquid to a predetermined location to permit utilization of the heat content thereof.