Abstract: A solar-powered hot air engine has a cylinder with hot and cold ends, and a solar collector directing radiation through a window into the hot end of the cylinder. A thin layer of regenerator material having low thermal conductivity is placed on the face of the displacer piston at the hot end of the cylinder, and a layer of material with high absorptivity and low emissivity covers the regenerator material and the interior surface of the cylinder to maximize absorption of the solar energy within the hot end of the cylinder.