Installing a solar swimming pool heater can significantly reduce the cost of heating your pool, according to the U.S. Department of Energy. If your pool includes a pump to recirculate water, you can easily tap off a portion of the flow to send through a homemade solar collector. Make your collector out of black irrigation hose or 1/2-inch garden hose. You can simply lay out the hose on the ground in a sunny location near your pool, but your collector will be much more efficient if you attach the tubing in a spiral shape on a wooden base panel.
Apply black paint to the face of your plywood piece, which will serve as the base for your solar collector. The black paint will increase the amount of solar heat produced. Trim the plywood with 2-by-2-inch boards if you will be mounting glass over the solar collector hose. You can staple silver Mylar material, often referred to as a "space blanket," to the plywood to reflect more heat back at the collector hoses.
Attach the 1/2-inch black irrigation hose or 1/2-inch black garden hose to the collector base in a large spiral. Screw pipe brackets to the plywood base to hold the spiral in place. Don't overtighten the brackets and crimp the hose; it's important that water be able to flow freely through the spiral as it gets heated.
Install a tee fitting in the tubing on the outlet side of your pool pump. On the new outlet of the tee, install a 1/2-inch ball valve so you can regulate the amount of water that goes into the solar collector. Don't try to force all of the water from your pump outlet through the solar collector. This will just place additional strain on your pool pump. You want the water to move slowly enough through the solar collector to pick up heat before emptying back into the pool.
Install a reducer after the ball valve to bring the size down to the 1/2-inch hose used for the solar collector spiral. If you're using garden hose, install a male garden hose connector on the output side of the ball valve. Secure the fittings with pipe clamps and tighten everything securely, because this system will be under pressure from the pool pump.
Aim your panel to receive the maximum amount of solar energy possible, usually due south. However, depending on your location and the tilt of the collector, the solar collector can face up to 45 degrees east or west of due south without a significant decrease in performance, depending on your location and the tilt of the collector, according to the Energy Savers website. Recommended tilt is an angle equal to your area's latitude, minus 10 to 15 degrees.
Increase the efficiency of your solar collector by covering it with glass or glazing. Plexiglass won't trap the sun's ultraviolet rays and hold the collector temperatures as high as glass will. Plexiglass yellows when left in the sun -- unless it is the more expensive Lexan type -- further reducing the retained heat.
Use a pool cover for a boost to your solar collector's efficiency. Most of the heat loss in a pool occurs at the water's surface through evaporation. A pool cover will help keep that heat in. Get a transparent cover that traps UV rays and you can add more heating to your pool. A cover also helps keep your pool cleaner.
Mount the inlet for your heated water where it won't splash on swimmers. The water coming from your solar collector can get quite hot on a sunny day. Never swim in a pool that is partially covered with a pool cover. If you come up under the cover, you may not find any air to breathe.