Pool Owners Warming To Solar
The fastest-growing market for solar water systems is swimming pools. Last year, about 95 percent of the square footage of all solar collectors shipped to U.S. markets were for swimming pools. And there are good reasons why the number is that high. Solar heating systems for swimming pools can be very cost-effective. A recent analysis of such systems for pools in Florida found that homeowners generally recoup their investment in 1.5 to seven years. A system typically costs from $2,000 to $4,000 installed.
A solar heating system for pools uses the same principle as a garden hose lying in the sun. When you turn on the faucet, out comes hot water. The sun's energy has been absorbed by the hose and transmitted as heat to the water inside. The hose acts a solar collector. For a pool, the filtration system pumps water from the pool to the solar collectors, which might be on the roof of a pool house or somewhere else near the pool. There, the water is heated through solar radiation and returned to the pool. Because of the large volumes of water being heated, pools require large collectors - sometimes they are as big as the pool's surface area itself.
But they differ from domestic solar hot-water systems -those for heating water inside the house - in several ways. First, these collectors are relatively low-tech compared to the glass-covered collectors for domestic water systems. Instead they may be made of black polypropylene plastic, rubber mats or black, plastic pipes. The collectors also warm the water to a relatively low 76° to 82° F, rather than the 120° necessary for domestic use. Finally, a pool system does not require a storage tank because the pool serves as one.
The market for solar pool-heating systems has been strong, with about 25,000 systems sold in the United States in 1999, according to the Department of Energy. The Solar Energy Industries Association says more than 500,000 swimming pools nationally are heated with solar water systems. Many of the new systems replaced existing electric or gas heaters that can be costly to run. In many cases, however, solar pool heaters are added to unheated pools, allowing the owners to use their pools for several more weeks - or even months - each season.