Instructables user, TheNaib, has written a tutorial on how to create a solar thermal water heater for under five dollars. It will involve a fair amount of DIY, but nothing too complicated. It's designed as a fun project, but with some tweaking it could see real applications, "Its a great way to learn about using the renewable energy of the sun to produce useful effects, in this case hot water. You can use these instructions to build a device that will actually heat enough water to use in the home, but it would require modifications."Not only is it creating hot water using completely renewable energy, but it is also created from recycled scrap parts like the coolant grill from a refrigerator. If you do try this out, be warned that it can really heat up water quickly, and to quite an impressive temperature, "A word of warning, this panel works VERY WELL. We tested it on a very sunny day and within seconds the water coming out of the panel was hot enough TO SCALD. I burned my fingers. This very hot water is only formed when the water inside the panel is allowed to sit for about a minute without moving. If the water is moving (do to the gravity siphon) the water exiting the return pipe is about 110 degrees, and while hot, will not burn you."
If you are thinking of trying this out then read the comments on the tutorial page, because lots of users have suggested ways to improve the design. Get in touch and let us know how you get on. ::Instructables