Abstract: An apparatus for concentrating solar energy upon the surface of a collector containing a circulating heat transfer medium, whereby the radiant energy may be absorbed and utilized. The apparatus includes a housing supporting a hemispherical reflector for gathering incident solar radiation and directing the reflected energy upon an arcuate fluid-bearing tubular conduit, which is adjustable seasonally for optimizing collection of solar rays. The geometry of the combination is so arranged that the reflected energy traverses the collector in response to the angle of solar rays falling on the concentrator without need for diurnal tracking.