Composite solar absorber coatings

A composite coating for a solar collector absorber wherein solar radiation impinges on one surface of the absorber, and said absorber is adapted to transfer energy so received from the impinging solar radiation in the form of sensible heat to a working fluid in communication with a delivery surface of the absorber comprising;

• a smooth surface absorber substrate;
• a first coating of solar radiation absorbing metal oxides, said metal oxides selected from a group consisting of antimony doped tin oxide, tin doped indium oxide and iron oxide;
• and a second coating of infrared radiation reflecting metal oxides, said second coating metal oxides selected from a group consisting of antimony doped tin oxide, fluorine doped tin oxide and tin doped indium oxide, said first and second coatings being deposited so as to form a composite on at least one of the other and the substrate in an order of deposition such that the first coating lies in back of the second coating with respect to impinging solar radiation such that the composite exhibits an absorptivity characteristic .alpha. of at least 0.85 for the solar radiation range of about 0.2 to about 2.0 micrometers and an emissivity characteristic of less than 0.2 for energy in the infrared range of about 2.0 to about 20 micrometers.