A system that uses the sun's energy rather than electricity or gas to heat water.Water heating accounts for about 20% of residential energy use and 7% of commercial energy use. A solar water heating system can significantly reduce the fossil fuel or electricity required to heat this water. A solar water heater typically uses glazed collectors that are roof-mounted and connected to a preheat storage tank. Fluid is pumped to the collectors where it is warmed by the sun and returned to a heat exchanger where heat from the fluid is used to heats the water in a preheat storage tank. A backup water heater is installed in series with the preheat tank to maintain the desired water temperature during extended cloudy periods. Most manufac