Solar Pool Heating
How does a solar pool
Solar heating systems are one of the most cost-effective applications of solar energy. It is relatively simple to integrate a solar water heater since most pools require a pump, filter, and plumbing. With a solar energy system, the pool’s water is pumped through the filter and then through a solar energy collector instead of directly back to the pool. The sun heats the water in the collector before it returns to the pool.
Collectors for heating a pool normally do not require glazing or insulation because they operate during warmer months when solar radiation and ambient temperatures are relatively high. This allows for a simpler design that is usually less expensive than collectors for domestic hot water. Many pool collectors are made of heavyduty rubber or plastic treated with a UV light inhibitor to extend the life of the panels. The advantages of plastic collectors are that they’re usually less expensive and weigh less than metal collectors.
Unlike solar domestic water heating
systems, which raise a small amount
to a high temperature of about 140°F, pool
heaters raise the temperature of several
thousand gallons of water to about 80°F
by circulating the water at a relatively fast
rate through the collectors. This allows
most of the solar energy falling on the collectors to transfer to the
Solar energy not only can be used for heating residential pools but
also for larger
commercial and public pools.
Metal collectors generally are made of
copper tubing mounted on an aluminum plate.
The disadvantages of metal collectors are
that they are more susceptible to corrosion
and freeze damage, and the copper tubes
may react with your pool’s chlorine if the
pH level falls below 7.2. Too many copper
ions in pool water may form dark-colored
precipitates, which can coat the pool’s
walls. This discoloration can only be
removed by draining, cleaning, and repainting the pool. This problem
can be reduced
if the pH level is always kept above 7.2.
The area needed for collectors to heat your pool depends on many factors. A general rule of thumb is that the collector surface area should equal at least one half of the pool’s surface area. In a relatively sunny climate, this additional heating helps extend the swimming season into spring and autumn. In cooler and cloudier areas, you may need to increase the collectors’ surface area to equal the entire surface area of the pool. Collectors can be mounted on roofs or anywhere near the pool that provides the proper exposure, orientation, and tilt toward the sun.
Collectors can be
mounted on roofs or anywhere near the pool that provides the
proper exposure, orientation, and tilt
toward the sun. The optimum collector
orientation is south, but west-facing orientations are good if the
area is increased to at least 75 percent of
the pool’s surface area. East-facing orientations are marginally good.
The tilt of the
collector is as important as the orientation.
For heating primarily in the summer, the
tilt should equal the latitude where the
pool is located minus 10 to 15 degrees.
Where optimizing the tilt is not possible,
for example on an existing roof with a
high slope or on a flat roof, increasing the
collector area may be necessary to achieve
the desired pool temperature.
One potential benefit
of roof installation is that it may reduce the cooling load of the
building that it’s located on, since it puts
the solar heat into the pool water and
keeps it from radiating into the attic and
the conditioned space below.
Solar Rating and Certification Corporation
The Solar Rating and Certification corporation currently administers a certification, rating, and labeling program for solar collectors and a similar program for complete solar water heating systems. Collector testing apparatus SRCC’s certification program operating guidelines, test methods and minimum standards, and rating methodologies require the performance of nationally accepted equipment tests on solar equipment by independent laboratories which are accredited by SRCC. The test results and product data are evaluated by SRCC to determine the product’s compliance with the minimum standards for certification and to calculate the performance ratings. Equipment which has been certified and rated by SRCC is required to bear the SRCC certification label which shows the performance rating for that product. In addition, each certified product is published by SRCC in a directory. Each product’s directory listing contains information on the product’s material and specifications as well as the certified thermal performance.read more