this won't help...
this technology has been around for years... ask any Boy Scout that purified urine into drinking water using a solar still built from a bowl, a cup, a rock, and a piece of sheet plastic. (Google Solar Still Plans - Search engines are your friend).
The reason this won't help is that it takes all day to purify 4 ounces of water.
Besides, most people that need to make fresh water don't live by the ocean.