Workers install the array of photo-
voltaic panels and solar thermal
collectors that provide electricity
and hot water to the Whalens'
house. Photo by Pete Beverly,
courtesy of National Renewable
Energy Laboratory

Solar Water Heating

Using solar power to heat water for swimming pools has been common in Sunbelt states for years. The pool pump sends cold water from the pool to solar collectors, where the water absorbs heat from the sun and then flows back to the pool. This dramatically reduces, or even eliminates, the cost of warming water for a swimming pool.

Solar water heating systems for potable water (water that is safe to drink) typically have two main parts: a solar collector and a storage tank. The sun is used to heat water or a heat-transfer fluid.

• Direct circulation systems pump potable water through the collectors and then store it in a tank, which could be a modified standard water heater tank.
• Indirect systems pump heat-transfer fluid through the collectors, and then transfer the heat to potable water through a heat exchanger. In colder climates, a drainback system keeps water from freezing in outdoor pipes.

PATH (Partnership for Advancing Technology in Housing) says the material cost and professional installation of such systems range from $2,500 to $3,500. (Such systems produce about 80 to 100 gallons of hot water per day.) Because solar water heating requires very little electricity to operate and burns no fossil fuels, it offers an environmentally sound way to heat water.

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