Abstract: A solar energy collector system providing a mechanically oriented parabolic trough direct radiation collector having along the focal line a portion of a first fluid conduit system and outside the focal line a portion of a second fluid conduit system, sectionally in arcuate array about the first fluid conduit system; greenhouse energy-collection effect to conserve heat at the fluid conduit systems is also provided by means of a second collector system including a glass-front enclosure over the parabolic trough collector, and preheating of fluid entering the solar heat collection system is provided by means of an insulated compartment behind the parabolic trough through which return tubing of the first and second fluid collector systems pass; a valve provides for separate or for serial connection of the two systems; and an aluminum foil covering over a parabolic form provides for renewal of the reflective surface.