Abstract: An evacuated, one-wall tubular housing having a reflector positioned at the opposite side of the tubular housing from the radiation energy of the sun. The tubular housing includes a solar energy absorber member of a cylindrical shape, for example, and a metal tube provided for maintaining an energy absorbing media such as water in good heat transfer relationship with the absorber member. The system can improve the efficiency of the total energy collection without the need to track movement of the sun or focus the reflected radiation upon a particular point. The reflector has a curved reflecting surface corresponding to a segment of a cycloid or trochoid curve. In the case of an array of the tubular housings, the cycloid or trochoid curve of the reflecting surface is defined as a function of the tubular housing diameter and the distance between the adjacent housings.