In its most basic form, a conventional solar still consists of a basin of undrinkable water that is set beneath a transparent cover. The water evaporates as it's heated by the sun, condensing on the inside surface of the cover. That condensation – which is pure, clean water – trickles down the cover and is collected in a separate receptacle for drinking.
It's a clever setup, but it also takes some time to produce significant amounts of potable water. In an effort to speed the process up, scientists at Russia's Ural Federal University have developed an experimental new solar still that incorporates a rectangular basin (with a hinged transparent cover), inside of which is a horizontally oriented black steel cylinder.