Solar energy collection system

A multiple tube solar energy collector having a diffusely-reflecting surface positioned behind the collector tube array. Multiple double walled collector tubes are connected into a manifold for circulation of a working fluid through them. The working fluid is heated by solar energy as it flows through the tubes. A diffusely-reflecting surface behind the tubes reflects back to the tubes both direct beam and diffuse solar radiation which fails to strike the tubes directly. This system allows efficient operation of a tubular solar energy collector without requiring focusing or polished reflecting surfaces. The tubes are preferably no more than four tube diameters apart, on centers, and no more than four tube diameters above or separated from the diffuse-reflecting surface.