How a Solar Pool Heater Works How a Solar Pool Heater Works

A solar pool heater can significantly reduce swimming pool maintenance costs. Heating a swimming pool, particularly an outdoor pool, can be one of the most expensive aspects of swimming pool ownership. Unlike gas, electric, or heat pump pool heaters, solar pool heaters have very low operating costs. Most solar pool heaters consist of three main parts.


A pump circulates the pool water through the solar pool heater system. The pump could be powered by oil, gasoline, electricity or other types of fossil fuels, but for the ultimate in efficiency you can build or buy a solar pump. A low voltage direct-current pump can easily be converted to a solar pump. Also, evaluate the distance between the pool, filter and collector, as well as the average area weather conditions. If the pump will need to carry water over a longer distance, a smaller-diameter pipe will be more efficient; however, a smaller-diameter pipe will also be more prone to freezing during the winter.


Water begins its journey through the solar pool heater at the filter. The filter removes debris, like leaves or twigs, from the water before it goes to the solar collector. A standard swimming pool filter can be used in a solar pool heater. Though the filter is an important part of of the solar pool heater, the pool owner can increase the efficiency of the solar pool heater even more by cleaning the pool regularly with a swimming pool vacuum hose and a skimmer net.

Solar Collector

A solar collector is a system that consists of both solar panels that collect the sun's rays and tubes or pipes that heat the water. The solar panels warm the tubes, both by focusing the sun's rays directly on the tubes and by collecting the solar heat energy around and redirecting that energy into the tubes. The water is pushed through the solar collector and heated by both passive methods and active methods. In extremely warm climates, a solar collector can also be used to cool the pool water by forcing the water through the collector during the cool nighttime hours.

The tubing and reflectors necessary for building a collector can be purchased at most neighborhood hardware stores. The optimal collector size depends on the size of your pool, as well as the temperature at which you intend to keep your pool. To maximize the sun's heat, collectors should face the sun's midday rays. They can be mounted vertically on a fence or horizontally on a roof.

Flow Control Valve

A fourth part of a solar pool heater is a flow control valve. This piece of the solar pool heater is not essential but can add additional savings to your solar pool heating system. This is an automatic or manual valve that diverts water when the pool has reached a sufficiently warm temperature. At this point, the water simply bypasses the collector and returns to the pool. When the pool water becomes cool, the valve reverses and the water is again sent to the solar collector to warm up. You can build or buy a flow control valve at a plumbing specialty store.

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