How to Build a Solar Pool-Heating System
To green up your lifestyle and save a bunch of money, you can create a simple homemade solar pool-heating system. You lower the submersible pump into the pool water so it'll always be primed. The pump runs off the 12VDC that the PV module supplies. The amount of water the pump passes through the solar collector panel depends entirely on how much sunlight is incident on the PV module: At night, the pump doesn't run at all. On cloudy days, the pump runs slowly. When it's sunniest, the pump is cranking full speed.
Because the heating system pump is separate from your filter pump, you can run your pool filter pump for only two hours a day without having any effect on how much heat you get from your collectors. In some locales, the power rates are much different during day and night; you want to run your filter pump at night, but you need to run your solar collectors during the day. With this system, you solve that problem.
A solar PV panel to power the pump costs about $130, and a pump costs around $40, for a total of $170. You keep your power bill for the pool pump to a bare minimum, perhaps saving you enough in one season to pay for all the parts of your new system.
You need to get a submersible pump with enough head pressure to raise the water up to the height of your collector. To determine ideal head pressure, measure the vertical distance from the water surface to the collector and add 4 feet.
If you put the collector on the ground, almost any pump will do the job. If you can put the collector below the surface of the pool, you can get help from siphon physics.
You need wiring, a solar collector, piping, and a PV module. A 12VDC panel should be strong enough to power your pump.