Abstract: A reciprocating solar engine includes at least one cylinder 3 which has an essentially transparent head 4 and a pistion 12 disposed in the cylinder 3. A gas-particle mixture 7, 8 is injected into the cylinder 3 between the piston 12 and the transparent head 4. Radiant solar flux is directed through the transparent head 4 so that the gas-particle mixture 7, 8 is heated and the piston 12 is pushed away from the transparent head 4. The engine further includes a device for allowing the radiant energy flux to be directed at the transparent head 4 during only a portion of the operating cycle of the engine.