Water heater

Solar water heating systems have a good economic payoff, and are manageable systems to install or build.  Some of the solar water heating designs are simple and low cost.  You can save a great deal of money by building your own system -- several thousand dollars.  There are dozens of free plans listed below that should meet just about any need. 

Simple batch systems are basically a tank painted black housed inside of a glazed box -- they work well in warm climates, and can be used in cold climates if drained for the winter.