My Homemade Solar Pool Heater
* Due to how popular this page is, (far beyond what I expected) I have taken a little time to update it and answer the questions I am getting in my e-mails. Scroll to the bottom of the page for the FAQ's.
This is the finished product. I plan to add 1 more row of five panels in the future. Basically the old hose laying out in the sun, except to make a real difference in pool temperature there is a total of 2000 ' of black hose. Cost when I built it 5 years ago, around $300 for tubing and PVC, the framing materials came from scrap. I needed to re-shingle my roof and had to take it down so while it was down I cleaned and repainted it and here are the pictures.
Click here to see where I get my scrap aluminum
On the left is the front of the panel. It measures 34" outside and 30" inside the frame. That is the smallest I could make the frame and still fit a 100' coil of poly tubing inside. The frame is made of 2" x 2" aluminum extrusion that is manufactured for screen porches and pool enclosures in the South. I cut 4 pieces with a 45 degree angle at the corners and then held them together with 4, 2" x 2" angle brackets. On the right, the back of the panel is covered with aluminum coil ( 2- 16" wide pieces) and then reinforced with 1" x 2" aluminum extrusion. I am a contractor and specialize in Pool Enclosures and that's where I get the scrap aluminum. If you live in the south you might be able to get this stuff for the price of scrap metal or less if you go to an aluminum screen enclosure company.
On the left, a panel freshly painted with Rustoleum black paint. On the right a 100' roll of 1/2 " poly tubing is carefully coiled up and held down with a 1 x 2 extrusion screwed into the center area. I had to really work at making the tubing coil this tight and stay in place. I ran hot water thru the tubing to make it soft and used lots of bricks to hold it down till I finally got it in shape. It is important not to kink the hose as once kinked, it is hard to get it not to kink again.
I laid 2 x 4 's painted black on the roof and fastened them down to angle brackets installed under a shingle tab. Each panel was then screwed down into the 2 x 4 with 3" screws. On the right you see the manifold made of 1 and a half inch PVC with inch and a half by 1/2 " threaded T's. The splices and connections for the tubing are in the irrigation dept at the building supply store. I may one day cover this array with clear corrugated plastic, but for now it's working as is
*Updated - How it works: OK, beginning just after the water leaves the filter there is a T with a valve that diverts the water through the T when closed . This valve when open allows the water to return to the pool without going through the solar panels. Closing the valve part way splits the water. With the T fully or partially closed the water goes up to the roof to the top of the panels. At the top of the panels is a row of 4 fittings, 1 for each series of 5 panels. I have 4 sets of 5 panels. The water from each fitting then goes down through 5 panels and all the water is then collected together again to run down the roof through a pipe that T's back in to the return water line to the pool.
Q. I like your design, how well does it work?
A. It works OK. It is just black pipes in the sun. It really isn't much different than other pool heaters. The performance varies by a number of factors. Most important is the amount of direct sunlight it receives. Due to my house's roof layout, my panels face East and would do much better facing South or West or I think laying the panels flat would be best overall. Next is just how much water you can circulate through it. I found that my pool pump was not strong enough to force all the water leaving the pump through my system especially if the filter is dirty, decreasing pressure. I have a valve that I close to divert only part of the water. Diverting all of the water bogs down the pump and actually circulates less water. I believe the optimum placement for these panels would be a flat roof. Due to the spiral tubing the pump has to be pushing the water up and down and up and down through the spirals. Two things that might help lessen the load on the pump would be laying the panels flat and second purging all the air from the system and making the connections airtight so that whenever the water is moving down it is siphoning the water going up. Also, I'm not sure about the size of the pipes going from the pump to the roof. I started out with one and a half inch pipe and planned to switch to two inch. Most solar companies use 2". After thinking about it I thought a 2" pipe would make an even heavier column of water for the pump to lift so I went to 1" pipe. This did seem to lessen the load on the pump but I think performance also decreased. I've already replaced the pump twice in 14 years and suspected it was too much load on it that caused it to fail. I think 2" pipe probably will do better and I will swap it out next time I update the system.
Q. How much does it heat the water?
A. That depends on how much water you can push through it. In my setup the water coming out is about 10 degrees warmer than going in. BUT, if you can push more water thorough, faster then the water coming out will not get quite as warm but because you are circulating faster I believe the cumulative effect would be improved performance. If you slow down circulation you can make the water coming out VERY hot but it will be a much smaller amount of water.
Q. How big is your pool?
A. My pool measures 30 feet x 12 feet x 4 feet average depth or about 11,000 gallons.
Summary: I think this system has a lot of room for improvement. If you decide to build something similar to this remember, it's just black hoses in the sun. I used what I used mainly because it was the least expensive parts I could find. I'm thinking about trying other methods without spirals. Maybe unrolling the tubing and stretching it out in the sun to make straight runs, or maybe using CPVC, but all that means a lot more fittings, connections and cost. Let me know your ideas and good luck
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