Pool Heating

Using solar water heaters to heat swimming pools and spas is very cost-effective. Payback can be as low as 2 years, and utility bills are much lower than they would be using a conventional heating system.

The pool's existing filtration system pumps water through the solar collectors, and the collected heat is transferred into the pool. Because solar pool-heating collectors operate just slightly warmer than the surrounding air temperature, these systems typically use inexpensive, unglazed low-temperature collectors made from specially formulated plastic materials. Glazed (glass-covered) solar collectors usually are not used in pool-heating applications, except for indoor pools, hot tubs, or spas in colder climates. In some cases, unglazed copper or copper-aluminum solar collectors are used.

Off-the-shelf packages are generally appropriate, and maintenance of solar pool-heating systems is minimal. The systems are pre-engineered, and can be sized for any pool by adding additional solar panels until an adequate square footage of solar collector area is achieved.

The only moving part on a solar pool-heating system is the diverting valve. This valve controls whether or not the water circulates through the collector loop. When the collector temperature is sufficiently greater than the pool temperature, the water is diverted from the filter systems through the collector loop. The water bypasses the solar collectors during nighttime or cloudy periods. Some smaller systems are operated manually or with timers, but larger systems are operated by electronic sensors and controls.

Adding a swimming pool cover will further enhance the temperature of a swimming pool, and should be considered along with the solar pool-heating system to prevent loss of heat to the atmosphere.

The market for solar pool-heating systems has been strong over the years, with approximately 25,000 systems sold in the United States in 1999. This number represents about one-fifth of all pool heaters sold annually. Solar pool heaters often pay for themselves in 2–4 years when replacing a conventional pool heater. However, in many cases solar systems are added to existing unheated pools, allowing the owners to make use of their pool for several additional weeks or even months each season. Contact the Solar Energy Industries Association to locate a solar pool-heating system retailer near you.