Abstract: The solar heater comprises an elongate concave reflector having a reflecting surface consisting of two interconnecting portions which are substantially symmetrical about a longitudinal plane of the reflector. Each portion in section is of substantially compound parabolic curvature. A heat absorbing device is disposed within the space defined by the reflector substantially symmetrically about said longitudinal place. The heat absorbing device includes a duct for receiving and conveying a heat transfer medium, said duct having surfaces in the form of plates extending laterally of said plane towards side regions of the two portions. Side plates extend downwardly from the distal edges of the laterally extending plates.