Introduction: Do-It-Yourself Solar Swimming Pool Heater

Picture of Do-It-Yourself Solar Swimming Pool Heater

I made this solar-powered swimming pool heater out of common materials anyone could get, with ordinary tools most average homeowners have (or can borrow from friends). A friend of mine named Ace gave me a sliding glass door that was going to be thrown out from a job site he was working on (he's a roofer, and the door had some minor cosmetic damages to the metal frame).

Step 1: Building the Collector Box

Picture of Building the Collector Box

I decided to make it out of pressure treated 2�4s and 3/43 plywood - the glass had leaned against my studio for over a year and you can see weeds and the weather had them filthy (wow I need to pressure wash my siding):

Step 2: Sizing the Box

Picture of Sizing the Box

So the size of the collector box was dictated by the glass size (76″ x 46″). Here’s my little helper buddy Muggy (my 6 year old son) helping me lay out the copper fittings - he was a big help throughout the entire project :) . Also you can see part of my German Shepherd Hoppy - she was NOT a big help:

Step 3: Copper Flashing Backing Plate

Picture of Copper Flashing Backing Plate

I ordered a 102 x 203 roll of heavy copper flashing .0216 (standard heavy weight for larger craft work, roofing and range hoods etc.) from Storm Copper Components - they are great, lowest price I could find and when I unrolled it it was almost 63 longer than 102 :

Step 4: Manifold and Backing Plate

Picture of Manifold and Backing Plate

I cut it in half and laid the two sheets under the copper manifold I made from 1/23 copper tubing I got from Lowes (the total copper cost in this project was around $250.00):

Step 5: Soldering the Manifold to the Backing Plate

Picture of Soldering the Manifold to the Backing Plate

Then I had a hard time soldering the tubing to the flashing, the heat tended to make the flashing buckle - I screwed the tubing down tight to the flashing with metal strapping, and just did as much as I could - skipping spots when the gap got over 1/8 of an inch or so. Still I made contact with around 70% of the tubing I think:

Step 6: Building the Support Structure

Picture of Building the Support Structure

I used my deck for part of the support, and sunk 2 4×4 posts for the other side. There is solid bedrock about 8 inches down there, so I dug big holes, used a rock hammer-drill to drill holes into the limestone at angles and put 1/2″ rebar in the bottom, which I then filled with 4 - 80lb. bags of premix concrete (we get some serious thunderstorms with strong winds):

Step 7: Calculating the Angle and Running the Supply Pipe

Picture of Calculating the Angle and Running the Supply Pipe

I mounted it at a 45° angle, which may seem strange (my latitude is 38.42444) but here’s my reasoning: According to this cool sun angle calculator, that is approximately the optimum angle for me during early April and late September between 10:00AM and 11:00AM, which is when I need the heating most - during the middle of summer the water sometimes gets too warm, so maybe I’ll be able to run the system at night and radiate some excess heat.

For the supply side, I tied into the pipe going from the filter to the jet, and used 3/4″ PVC which I buried in a shallow trench (There is a tee with a drain plug at the lowest point, for winterizing):

Step 8: Hooking the Supply Pipe Up to the Pool Pump

Picture of Hooking the Supply Pipe Up to the Pool Pump

I thought I might need a valve between the jet and the output to the heater, but it wasn’t needed - there is a lot of pressure going to the solar heater:

Step 9: Mounting the Box

Picture of Mounting the Box

I painted the interior flat black, and used weather stripping between the wood strips supporting the glass and the glass instead of silicone - it’s not airtight (there are several “weepholes” drilled in the bottom for condensation). This way if I ever need to I can unscrew the trim and remove the glass easily:

Step 10: Intake Valve

Picture of Intake Valve

I can turn it on or off with a simple valve:

Step 11: The Outflow Pipe

Picture of The Outflow Pipe

The outflow is copper tubing:

Step 12: Install the Glass and Trim

Picture of Install the Glass and Trim

Here’s the finished heater with glass installed and trim (I’m going to treat the trim and support boards with the same color stain/water seal as the decking and the collector box when the weather forecast calls for a few days of sunny warm weather).

Here is a little data I’ve been able to collect:
It is flowing at 3 gallons per minute (180 gph), and at 10:30AM on a sunny day the pool temp is 58° (it was 54° this morning at 8:00AM). I filled a gallon jug with water from the outflow of the solar collector (20 seconds) and the temp was nearly 61° - so it looks like on a really hot sunny day I could hope for a 4° or 5° rise in outflow temp. I think the pool is around 10,000 gallons, but trying to figure the math of it makes my brain hurt (I’m a musician, not a mathematician dammit!) and I guess it really doesn’t matter - if it works and I get even a few more days of comfortable swimming per year, then I’ll chalk this up in the WIN column :)

BTW if you get a chance how about digging this? Digg this


andrefierens (author)2017-06-20

Genius ! Great Job !

With a Garden Hose : I made a Portable Solar Pool Heater 1,04 k Watt DIY, first I used a garden hose, Now a Intex Solar mat. So the module is Foldable and Portable. No need of electricity !

daveryder (author)2015-08-02

UPDATE 8-2-2015: Ok I have a confession to make here guys: I took my heater down 2 years ago, for a number of reasons I'll enumerate. 1. Every spring, no matter how thoroughly I drained and forced air through the pipes with my air compressor, somehow water would get inside the pipes and freeze, and every spring I would have to take it all apart and solder in couplers or hammer small splits back together and solder them all shut again - BIG TIME HASSLE. 2. Extra time swimming in the spring was really not that much, because you kind of want it to be good and hot outside when you want to swim, so even if the pool water was warm, when you got back out especially if it was windy, you were freezing. 3. Extra time swimming in pool in fall stopped making sense due to same issues in spring PLUS the fact that your maintenance goes WAY up from all the falling leaves etc.

I'm actually with leebarrett (way above comments 5 yrs ago) in that in mid summer it gets way too hot! I deal with that with a fountain I run at night that cools it off (a little bit) at night. So, bottom line, it was a fun project and good experiment, but unless someone smarter than me can figure out a way to keep the copper tubes from freezing, I honestly can't recommend this instructable anymore. Also, plastic tubing is not a viable alternative, I have a special needs child who drinks small amounts of the water even though I tell him not to, and I think his friends do, too - which is why I use the smallest amount of plain chlorine bleach as possible to kill off organisms, and knock down my PH with tiny amounts of muriatic acid and do it at night so everything gets distributed before kids swim in the morning. The hot sun would leech PCB's (or BPAs or whatever the hell heated plastic leeches) into the water from black tubing IMO - a risk I'm not willing to take.

I'm truly sorry if I wasted anybody's time/money with this instructable :(

Sincerely, Dave

TonyC247 (author)daveryder2017-05-06

Hi Dave. Unless you rotate your frame 90 degrees when draining it, the parallel configuration you've created will be almost impossible to drain completely, even with an air compressor. My guess is that the damage you experienced was restricted to the tubes below the input and output pipes? You would either need to add a drain plug on the bottom (at the lowest point), or reconfigure it into a serial flow system to prevent that. With a serial system and the cold inlet at the bottom with a backflow preventer, you could disconnect the system from the pool pump and rely on the thermosiphon (convection) to circulate the water. That would mean it would only move water through the system when the water in the collector was being heated and it would require no moving parts. If the flow rate wasn't high enough you could obviously add a pump to move the water.

SisoA (author)daveryder2016-02-25

Hello Dave,

You could use a Polyethylene hose. It doesn't leech BPAs (neither PCBs). It's a safe plastic and quite cheap. Was researching for a similar project when I found yours.

Cheers for your experience and best regards to you and your child.

andrefierens (author)2017-03-18

Hi Dave, some windscreens might help, feeling warm, when you get out of your Pool. You also might enjoying sunbafhing !

Thank you ! I love your instructable .

andrefierens (author)2016-07-16

This is the tittle of the Portable Solar Heater !

Portable Solar pool heater 1,04 k Watt DIY - Instructables

andrefierens made it! (author)2016-07-16

Genius ! Awesome !

I like it !

I made a Portable Solar Heater, it fits in a suitcase. Easy to drain ! With a Solar bag 1-2-3. See also Instructables.

JoshH20 (author)2015-08-04

You could try making it a closed system so that only the heat is transferred via a pipe inside the pool. Then you could add an anti-freezing agent of some kind to the system. It would need to be something that only prevented freezing though. As far as the too hot in the summer issue you could add a shut off valve that would let you restrict the flow to the pool when the heat wasn't needed. I'm just spitballing this so I haven't done any specific research into it. Just top of my head ideas.

cm3stars (author)2010-01-29

Nice work! I was wondering if a modified version might have the water intake at the top of the panel, say upper left. And the outflow at the lower right. That way if you had (10) six foot pipes in your manifold the water would have a 60 foot run in the pipe instead of 10 pipes each only running six feet. I think your outflow temp would be substantially higher.

GOOD OL BAD GUY (author)cm3stars2012-10-31

The object is to cool the collector, the longer the water is in the pipe the hotter the water AND the collector will be hotter, i.e., not cooled as well.

Like any heat exchanger the greater the temperature differential the greater the efficiency.

The rate at which heat is transferred is governed by three basic factors: 1) the type of materials involved (in this case, copper, black paint, solder, and water, all constants regardless of the length of pipe), 2) the surface area involved (the length of the pipe seems to be a factor, however, since the water is flowing, the diameter is more important), and 3) the difference in temperature. The temperature delta is the factor pointed out by Good Ol Bad Guy. In the collector, as the water flows from inlet to outlet, it increases in temperature and its ability to absorb heat is reduced. This can be mitigated by pumping more water.

daveryder (author)cm3stars2010-03-20

I agree.

AwlDuhrage (author)2015-08-02

I would have used a standard diverter valve (used with in-ground systems).

AwlDuhrage (author)2015-08-02

I'm a bit late to the party, by six years, a couple of comments, though. First, plastic will absorb heat from the sun and is a viable option for use in solar heating panels. Plastic is not as efficient as metal, and has heat and pressure issues that need to be mitigated depending on the environment.

Second, thermal convection will not help the flow of water through this system. The water be pumped through the tube will prevent any convection currents from being formed. Also, the tubes are too narrow for such a current. If anything, capillary action might contribute a small amount of force, however the tubing is probably too large for that.

Another comment about using more but shorter pipes to increase surface area is not quite correct. Each pipe uses a small length for the connection, so two 10 unit long pipes will have four connections whereas one 20 unit long pipe will have only two connections. If a connection uses say 1/4 inch of pipe, 1/2 inch more is lost when "1/2 length" pipes are used. On the other hand, short pipes, arranged vertically, will reduce the back pressure the pump has to work against (shorter head) and might have side-effect of reducing the flow at one end or the other of the panel. Either way, this will double the amount of connections, each one being a potential source of failure, and hence the work to build the system. I am curious as to what the optimum separation of tubes on the flashing is - too far apart and heat is left on the flashing, too close and the heat is distributed across more water - requiring more water (= more pumping = more power used, also means more pipe was used than necessary = higher cost with no gain) to get the same amount of heat from the water.

There is nothing wrong with the flashing buckling while being soldered, provided that it remains reasonably flat as in not curving so that the surface is not struck by the Sun. The important factor is that the flashing be connected to the tubing to maximize the heat transfer to the water. The 70% contact cited roughly translates to 70% as efficient as it could have been.

Pumping from the bottom has the benefit of using gravity to create back pressure to distribute the water evenly throughout the pipe, provided the inlet and outlet are at opposites ends (diagonally opposed corners) of their respective headers. My system will use a solar powered powered pump (eventually) and be mains-backed.

YvonL (author)2015-07-24

Great webiste, I have been looking for a way to use my pool for the winter as well as during the summer. Having a solar powerd heater would be great for that. Do you have any sources for getting the solar panels? It is not like you can just pick them up a Wal Mart.

dcgall (author)2015-02-06

I've been looking into some type of pool heating system. I live in Arizona, and once we hit June - heating is NO PROBLEM. Our problem is friends come to visit from the North during the winter months and expect to go swimming. Well, believe it or not, Arizona isn't 100 degrees every day and our pool only gets to 50 degrees during the winter months. I want to build a heating system that I can drag out a week before visitors, heat up the pool and put it away. At first I was mere minutes from building the Red Neck Pool Heater system that utilizes a copper tubing system that is heated by my propane grill. The reason I stopped was a post I read about copper turning the pool green. The last thing I wanted to do is screw up the pool chemistry.

After reading the posts here, it seems that copper is the preferred choice and barely a hint about pool chemistry. Is it because the solar water temp only gets to 80 +- degrees? Any educated words on this topic? AND, can I only expect to get the temp to 80 +- degrees? I prefer 85. Thanks, I appreciate any guidance.

fabianchess (author)2013-12-07

I have built one of these back in 1978, instead of copper I use tar paper and black hose, starting from the center it slowly work in a circular fashion to the out side of the bull eye. I put a splitter on return water from the filter and could gage the tempure coming in to the pool and all it cost was the cost of clean pool water. I did build a box and put Plexiglas on the top to trap the heat on the black hose and tar paper.

mr fat (author)2013-09-16

Brilliant job! I am wondering if vertical heating pipes would work better cold water in at the bottom?

vistal (author)2012-06-20

Copper and chlorine dont mix your pool will start turning green and the copper will soon be eaten away. great Idea i build them myself with black PVC/

useraaaaa (author)2012-06-18

who needs pool heater.
make pool cooler please.

chspyder (author)2010-05-16

Just a thought but copper is a very bad thing to have with the pool chemicals and causes staining. I have to bypass my heater when not used to keep the staining to a minim, this may be low cost heater but the stain remover is about 60$ for my size pool, and two to three times per season it adds up.
I am building a dome shaped heater with black flex hose (vacuum line) like in the new leslies flier and will post results.

dweston (author)2010-04-25

I added a new twist to this basic design - I installed a temperature switch under the glass (They sell at Lowes for around $17 and are for use atic vint fans) - the switch turns the pump on  when the air temp reaches 100 degrees inside the pannel, and off when the temp falls back below 100 so the it only runs when there is heat to transfer - seems to work well

glubash (author)2010-04-16

Nice project.  I have a couple of coworkers looking at doing something similar.  You mentioned that you might be able to radiate some heat during the summer months at night, any luck with that?  A small exhaust fan might help in that situation.

guynoble (author)2009-07-11

That looks like you did a really good job but a cheaper more effective option would probably be to place heat absorbers directly in the pool, such as a black thermal blanket floating on the pool surface. If you don't want to buy an expensive blanket, perhaps a couple of those large black plastic trays, intended for mixing concrete, floating on the surface. Cheap, easy to clean, stackable for storing and virtually indestructible. You could then use your solar panel for preheating water for the house instead. This way you'd be lowering your energy usage and making a difference to your fuel bills and the environment.

daveryder (author)guynoble2010-03-20

It works. You can't use pool water for your house. You worry about your bills, I'll worry about mine. All I wanted is for my family to enjoy more swimming time, and in that regard I succeeded.

leebarret (author)2010-03-20

Yeah I live in Houston Texas & I'm working on a pool cooler, since my 12,000 gallon gets too hot from july to sept! (like taking a bath) They sell pool covers for fairly cheap that will do the same thing in principle you are doing. They raise the water temp 5-10 degrees.

daveryder (author)leebarret2010-03-20

It's called a solar cover - I use that in addition to the heater - we swim one month sooner than most people around here, and one month later with the combination.

Plus, after a cold snap or rain, it heats up way faster. The whole point is getting more swimming time than you would get without the heater, and last year was a total success in that regard.

If you built one without the glass, and ran it only at night, it would work as a radiator and cool your pool down.

Utahtabby (author)2009-04-24

61 degrees still seems like FREEZING to be swimming in....In my opinion, ha! I need my pool temperature way hotter! also what is the point of using copper (other than it prevents algae) could you have used PVC or other metal, tin perhaps? I am clueless on this stuff so I am just asking, not criticizing.

daveryder (author)Utahtabby2010-03-20

Oh for sure, 61 degrees feels like ice! I like it 75+ for swimming, but it's all about getting it to heat up more quickly.

kaos211976 (author)2009-05-15

This is a fantastic project. Thank you for sharing it. I have been planning something like this for my pool for some time now and this has given me a lot of good research. Mine will be 10' x 4' and be mounted on my garage roof. I will be forgoing the glass as I don't see the need in my application. I will also be using Aluminium sheeting instead of the costly copper. Copper would be better but it will be too expensive. Thanks again.

daveryder (author)kaos2119762010-03-20

I thought about putting mine on the roof, but didn't know if the pump had the pressure to raise it that high without putting a big strain on it. Plus, I didn't want to mess up my shingles with a mounting system. Plus I hate heights.

guynoble (author)2009-07-11

Your pool will adopt the mean ambient temperature. If you want to raise the temperature you must put in more heat than it is losing to the surroundings. Perhaps you should therefore think about insulating the pool sides before you expend too much effort on heating methods. Its not a difficult calculation for any first year engineering student.

daveryder (author)guynoble2010-03-20

Maybe, but the whole point is getting more swimming time, and last year proved to be a big success - see my comment above reply to leebarret.

domestic_engineer (author)2009-04-18

nice instructable, but that's a lot of copper, and a lot of $. we're thinking of doing something similiar, but with flexible tubing and tin foil.

domestic_engineer, you can use pex tubing and make your own aluminum fins to fit around the tubing. You can use a 5/8's metal rod to make the grooves for the pex, a very very thin bead of silicone to adhere the pex to the fins. Make the fins wide enough to touch each other inside what ever size collector you build. Running the pex tubing in a serpentine fashion will allow you more mass in the collector. This is a good place to start
 This website is a wealth of info for any DIY'er  Have fun

annekaelber (author)2009-11-15

I'm aware of the better conductivity of metal over plastic/rubber. I'm curious if the "black garden hose in the sun" multiplied by how much more could be purchased for so much cheaper can overwhelm the benefits of using a metal like copper?

The original author states s/he spent $250 in *just* the copper tubing for a 76" x 46" solar heater.

I've seen, on, 500 ft of 1/2 tubing (designed for drip-type watering solutions I believe) for between $30 and $35. I used this page:
to do a rough calculation of how many feet of tubing I would use in a 4x4 box, which is approximately 300 ft of tubing -- well within my 500 ft mentioned above.

I'm still searching for ways to determine how much I might reasonably hope to gain in temperature via 300+ ft of black tubing. I welcome any suggestions or data input here.

As for the instructions, if we do decide to use copper tubing, we're definitely going to be referencing this Instructable! Thanks for sharing!


jonralph (author)2009-06-11

copper is the right material to use for this application. As has been said before plastic is an insulator and won't absorb any heat from the sun.

It does look like the flow of water is going to just run through the pipe nearest the inlet, it will always take the path of least resistance. There are 2 things you can do to improve this though, and they are both reasonably easy.

Flow should always be controlled on the outlet, not on the inlet. This has the effect of slowing everything down and not giving the flow an easy route through the pipes. This should help spread the flow over all the pipes.

Turn the panel so that it is vertical, with the valve at the top becoming the outlet and the inlet at the bottom. The valve on the outlet will keep the flow across all the tubes and also thermal convection will help move the water through the outermost pipes. As the water is heated it will rise naturally.

If you go for this please let us all know how you get on.

If you want to work out the volume, first go and look on the manufacturers website, it will likely say so.

if not, measure across your pool in meters(diameter), half of that is your radius. The area of a circle is radius x radius x 3.14. I am guessing that the radius of your pool is about the same as the panel is wide (76" so near as dammit 2 Meters) 2 x 2 x 3.14 = 12.56 Sq M is the area of your pool. For the volume of a cylinder in cubic meters you just multiply the area of the circle by the depth. So I am guessing the pool is about a meter deep? So

12.56 sq Meters x 1 meter = 12.56 cubic meters.

1 cubic meter = 264 gallons
12.56 cubic meters x 264 = 3315 gallons

measure your pool and work it out with your son for the fun of it. or measure it and pass the measurements on, happy to work it out for you

Nice piece of kit already though and any gain is a benefit.

davefredrich (author)jonralph2009-09-22

jonralph hows it .
my name is dave, joined today after reading your comments on pool solar. i live in a small town pennington south coast natal south africa. two things i would like to ask. one would ambient temp govern the size of a panel area.
2 working out your btu ratings for area water to be heated, not also depend on ambient temp. eg 20 square meters pool area, ambient temp 15 deg c
20 30 deg c
why i ask is our temp is similar 2 south coast america winter max 19 deg c summer +- 32 deg c would you design be worked on winter conditions.
dave richards.

Lynxspring (author)2009-07-17

Can you tell us what the pickup is on your heater? Like what the inlet VS outlet temp is compared to the outside air temp in a perfectly sunny day? (Delta T) thanks

hackinblack (author)2009-06-19

improvements to this design I see:- the copper pipes vertically NOT full length horizontally they are toooo long to support water weight and expansion,using more,but shorter pipes, gives a greater surface area (more heat!) and more strength (no leaks!) 2.put the inlet diagonally opposite the outlet for more efficiency

SurferGeek (author)2009-04-18

Wouldn't it be better to use plastic piping? Wouldn't using copper put metals into the water?

daveryder (author)SurferGeek2009-04-20

No. The plastic would put more toxins in. I drink from copper pipes everyday, and remember, the temp never gets above 80 degrees.

SurferGeek (author)daveryder2009-05-17

PVC piping is, and has been used for years in household for water pipes and as you state, the water never get's above 80 degrees there wouldn't be any leeching.

Copper is a good choice as it does have better thermal conductivity but PVC is a much cheaper choice of materials that will have no chemical reactions to other materials used in the pool or with other metals used like in the pump.

kaos211976 (author)SurferGeek2009-05-15

You have a point about the copper. I would say that an occassional metals treatment would fix this up.

thetech101 (author)SurferGeek2009-05-06

Plus most types of thick plastic piping are very good insulators. Metals transfer more heat than plastics. A good rule of thumb is "if it conducts electricity, then it'll conduct heat. If it doesn't conduct electricity, it won't conduct heat."

l8nite (author)2009-05-12

Any updates on the new design? You could modify what you have by cutting every other connector pipe and capping the stub to make a repeating "s". An added benefit of using copper is it helps control algae growth, copper wires are strung on a roof to prevent algae and moss growth, copper nails inserted around the base of a tree will kill it etc. Nice instruc!

kaos211976 (author)l8nite2009-05-15

I will be using the continuous "S" coil and forgoing the "T" connectors. My only fear is that the water will be too hot! LOL

TheCowStir (author)2009-05-11

Copper/metal is a better conductor of heat. So there will be more transfer of sun heat through the black copper pipe than there would be through pvc pipe. Plastic is more of an insulator.

kaos211976 (author)TheCowStir2009-05-15

Copper is the best, most cost effective, metal used to conduct heat into water. As a frame of reference, Copper rates 380.0 in conductivity whereas Aluminium is 180.0 (not bad for a common alloy) and PVC is only 0.12-0.16 (Polyvinyl). Painting the copper flat/matte black allows for more absorption as the shiny copper surface does not reflect the light energy away but rather draws it in.

strmrnnr (author)2009-04-20

I think you need to have the feed in the bottom and the exit at the top, so that a unit of water has to travel through all the pipe before exiting to the pool. As I look at it I can't help but see the water comming in and going straight across to the exit, leaving the water in the top and bottom pipes almost unmoved. It may help to turn it 90 degrees if you didn't want to change the piping. Tip on th esoldering to. If you have it all planned out, you can slit the flashing and solder it to the pipe through the slit from the back. Takes a lot more planning though.

About This Instructable




Bio: Just a normal guy - I like recording music with my band ( and working on my house
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