Hundreds of thousands of swimming pools across America are heated by pool solar collectors. Pool solar collectors are the most cost-effective common use of solar energy. Early pool collectors were made of copper but the newer plastic collectors have proved more reliable. You may have seen these black plastic collectors installed on south-facing roofs near swimming pools.
The collector area depends on what direction the collectors face, the amount of sun and wind at your site, how long you operate your pool, and the surface area of your pool. In sunny climates where the collectors face due south, and where there is little wind, the collector area should be about half of the pool’s surface area. But if you want to operate your pool from early spring to late fall, you could buy up to one square foot of collector for each square foot of pool area. Collectors facing away from due south suffer 15 to 25 percent reductions in capacity, so you need more collector area in these cases. Steady winds also reduce the collectors’ capacity.
Solar collectors should ideally be tilted up to an angle approximately equal to the latitude in your location. Pool collectors don’t need insulation or a glass cover because they are used during warm weather.
The pool water is routed through the solar collectors instead of the conventional pool heater when a control senses enough heat in the solar collectors. Your existing pool pump can circulate water through the solar collectors if it is big enough. Keep pumping costs low by using long-radius elbows for all piping bends, especially near the pump. When you install the solar collectors, you may want to replace your existing filter with the largest one that fits in your system. Larger filters save pumping costs, which can be substantial.
For more information, see the DOE’s EERE Clearinghouse.