Device for utilizing the heat energy of solar radiation

A device for producing usable heat from solar radiation and which is coilable into a roll comprising in combination:

• a first elongated flexible foil having at least one black surface;
• a first fluid flow conduit formed by a second flexible foil of a material which is pervious to solar energy positioned adjacent said one surface of said first foil with said first foil and said second foil being connected together in a fluid tight manner, along the outer edges to define a first closed space therebetween, first inlet means and a first outlet means, each communicating with said first closed space, for permitting the flow of a fluid heat carrier medium through said first space, and further sealing connections of said first foil to said second foil positioned to define an extended fluid flow path, within said first closed space, between said first inlet means and said first outlet means;
• and
• a second fluid flow conduit formed by a third flexible foil positioned adjacent the surface of said first foil opposite said one surface with said first foil and said third foil being connected together, in a fluid tight manner, along their outer edges to define a second closed space therebetween, second inlet means and second outlet means, each communicating with said second closed space, for permitting the flow of a separate fluid heat carrier medium through said second space, and further sealing connections of said first foil to said third foil positioned to define an extended fluid flow path, within said second space, between said second inlet means and said second outlet means.