Solar heater

A solar heater including an inclined corrugated radiant-heat-absorbing panel, with the troughs of the corrugations extending between the upper and lower edge-zones of the panel, a liquid-supply pipe affixed to the upper edge-zone of the corrugated panel and having orifices therein in registration with the upwardly-facing open ends of the troughs of the corrugated panel, a liquid-discharge pipe extending along and affixed to the lower edge zone of the corrugated panel and communicating with the troughs thereof, and a flexible plastic envelope enveloping said pipes and the corrugated panel therebetween, including an upper and a lower plastic panel, of which at least the upper one is transparent, said envelope having the bottom, side and top marginal zones of its two panels sealed to each other and having a sleeve at the inlet thereof through which the supply pipe extends and to which it is sealed and having a sleeve at the outlet thereof through which the discharge pipe extends and to which it is sealed.