Abstract: A device for collecting solar energy, for incorporation in a dwelling, especially in a tiled roof, comprises a heat-absorbing plate, ducting for a heat-exchange fluid for extracting heat from the plate, and single or double glazing over the plate, this glazing consisting of a plurality of radiation - transmitting tiles each having a recessed rear face defining a cell, whereby convection between the glazing and the absorbing surface is reduced or eliminated.

Abstract: A process for the purification of water comprises a step-wise procedure for heating and evaporating water to be purified at different location and then condensing water thus evaporated. The water is heated in the form of a sheet by solar energy while in a pan at least part of the bottom of which is capable of absorbing the heat content of solar radiation, and in which it is covered by a layer of liquid which transmits solar radiation therethrough, is immiscible with water and which has a vapor pressure less than that of water. The liquid is usually an oil. Various mechanical devices are disclosed for optimizing utilization of solar radiation reaching the pan. Evaporation of heated water removed from the sheet of water to the evaporator is preferably effected under reduced pressure.