Method and apparatus for converting solar radiation to heat energy

Method and apparatus for converting solar radiation to thermal energy for heating a gaseous stream such as air to be used for heating or drying purposes. The air or other gaseous mixture is flowed through an elongated heating passage defined by plastic film formed of solar radiation absorbing or opaque (black) material and the film is inflated by the fluid pressure of the gaseous stream passing therethrough. The heating passage is surrounded on top by an insulating space defined by the outer surface of the top portion of the opaque film and by an outer sheet of clear (solar radiation transparent) plastic film that is inflated into an expanded position by the gaseous insulating medium therein. Air or another gaseous mixture is flowed through the heating passage wherein solar radiation absorbed by the film is converted to thermal energy that is transferred to the gaseous stream.