Abstract: The sea water to be desalted is fine-sprayed through nozzles (3) against an underside (1b) of a plate-shaped element (1). The element (1) may, for example, be an aluminum plate forming a heat transfer medium and is exposed to solar radiation through glass cover plates (15). The water sprayed on the underside (1b) is distributed over the surface of the element (1) and is evaporated by the heat stored in this element. The water vapor passes through an outlet (27) to a condenser (10) in which it is condensed and finally through an outlet (12) in the form of fresh water which then is available, for example, for irrigating green spaces. The sea water to be desalted is preferably sprayed against the underside of the element (1) for only a few seconds at predetermined intervals. To clean the element (1), sea-water may be sprayed every hour for, for example, 1 to 1.5 minutes against the underside of the element (1) in order thus to rinse away deposited salt and impurities.