solar water heater

Water heating accounts for a substantial portion of energy use at many residential, commercial, institutional, and federal facilities. Nationwide, approximately 18％ of energy use in residential buildings and 4％ in commercial buildings is for water heating. Solar water heaters, which uses the sun's energy rather than electricity or gas to heat water, can efficiently provide up to 80％ of the hot water needs—without fuel cost or pollution and with minimal operation and maintenance expense. Solar currently represents 1％ of the water heating market (about 3％ of buildings have solar and it provides about 1/3 of the energy for each). In 2003 11.4 million sq. ft. of collector area were delivered by 27 manufacturers. Most of these were unglazed collectors for swimming pools, a very cost-effective application. Solar water heaters can be used effectively throughout China at residences and facilities that have an appropriate near-south-facing roof or nearby unshaded grounds for installation of a collector.