The concept of a solar water heater is simple:Â use the sun to heat up the water. Black tubing is very good at absorbing sunlight. We just need to pump the water through some black tubing. Of course, that tubing takes up a lot of space, so I prefer to put it on the roof, so it’s out of the way, visually. You can watch this short video of how I made my solar water heater:
The black tubing was purchased from a local Leslie’s Pool Supply. The pumps were purchased for reasonable prices from Surplus Center. The clear PVC tubing was purchased from McMaster-Carr. Be sure to buy UV resistant tubing and connections, or else the sun will degrade the plastic in a few months. I wired the pumps into a $15 automatic timer. It turns on at 9am and turns off at 6pm. The manufacturer of the solar water heater will suggest plumbing it in through your regular pool pump. I disagree with that. We run our pool pump at night when the electricity is a fraction of the cost of a daytime kWh, and run our pool heater pumps (much smaller pumps and lower electrical draw) during the day when the sun is out.
To properly finish the project, we would need to attach the solar water heaters permanently to the roof. I didn’t want to mess up our roof, so I let them just sit there. During a fierce windstorm they did blow off of the roof, but some very large trees had fallen in the neighborhood, so I don’t feel so bad. No damage was done, so I’m not too worried.
Gravity is no match for 70mph winds.
For only ~500W of electricity we are adding over 11kW of heat into our pool. Not a bad trade-off. While swimming in the pool you can definitely feel the hot water coming out of the outlet.  Now that we’ve got our Lily Pad Pool Warmers, we hope that the heat stays in!