Abstract: A solar collector of the tubular type comprising a solar energy transmissive outer tube encircling a solar energy converter inner tube disposed for having a flow of fluid directed longitudinally through it. The outer and inner tubes have respective opposing end portions sealed to one another and respective mid-portions radially spaced from one another for forming an interposed vacuum chamber. The sealed joints may include at least one flexible member disposed to compensate for differences in thermal characteristics of the inner and outer tubes. The inner tube is provided with an exhaust tubulation which communicates with the vacuum chamber for evacuating the chamber, and extends inwardly of the inner tube for producing turbulence in the flow of fluid to aid in the transfer of heat energy from the inner tube to the fluid.