08-05-2007, 05:45 AM
We are off grid and have a Solahart solar water heater (two panels) and a Takagi (TK2) on-demand propane heater. In spite of what I call a "partly cloudy climate" in Puna (about 1100' elevation) the Solahart provides lots of hot water nearly all the time. When we get dense clouds for more than two days the Takagi is a welcome backup source. The Solahart uses convection to store the hot water in an 80 gallon tank on the roof so no external power is required. It does have internal electric heating for backup but we did not hook that up as the huge kilowatt draw is not supportable by our photovoltaic system.