Originally Posted by
jonthepain
I built a solar water heater.
A friend of mine had just upgraded his 20 gal water heater to a 40, so he gave me his old 20. I stripped off the shell and the insulation and painted it black. I built a box around it out of 2x4s, R19, some foil covered foam insulation, Hardiboard, and some old window sashes and panes from old storm windows for the top and south facing side. It's sits out back next to my deck. I plumbed it so it's just upstream of my 40 gal electric water heater. It gets hot as hell in there I tell you what. The electric water heater almost never turns itself on now, unless it's been rainy or cloudy all day.
The whole deal cost me around $100. Found the plans online; apparently they were very popular during the great depression. go figure.