Solar DIY Swimming Pool Heater

rwongca · September 2014

Hi Everyone. I hope all is well and hoping someone can help me out to see if this setup will work for what I am trying to do. I am a complete newbie with solar power, so this would be my first project and I would go from there!

Background: I have an inground swimming pool roughly 15000 gallons. I live in the Palm Springs California area, so get lots of hot sun during the summer months. I used to use a solar cover for my pool which would heat the water up nicely and keep the warm water in during the evening. Few months ago the solar cover basically fell apart because it was the 2nd year and was expected. So, I am now using a liquid solar cover product I got from Amazon - http://amzn.to/W7uMJb. Seems to be working OK and water isn't evaporating as much and the product is supposed to keep the warm water in the pool in the evenings. However, it is not as effecient as a solar cover heating up the water for multiple reasons like evaporation and wind blowing over the water in the evening. So, what I am trying to do is heat up the water a little more during the day and hope the liquid solar cover does its job and keeps the warm water in. It has been so nice going in the pool after work and NOT having to take on and off the solar cover so want to see if this solution might work.

Project: DIY Swimming Pool Heater. What I am thinking of doing is buying a 100 watt solar panel and connect it to a DC Pump (See links to actual products below). I would have the pump connected to a 100-400ft black hose that would be in direct sunlight. The water would flow through the pipe during the day and returning water into the pool would be a little warmer.

RENOGY 100 Watt Solar Panel $150 - http://amzn.to/1nwuXFr
RENOGY 100 Watt Solar Panel and Starter Kit - $184.99 - http://amzn.to/1sXEAjy
DC Pump #1 - $69.00 http://bit.ly/1q8mEVg
DC Pump #2 - $79.00 http://bit.ly/1rgB2uq

Questions. So, few questions for you experts:

Q1 - Can I connect the solar panel directly to the DC Pump. From my understanding, I can do this if I hard wire/connect the positive to positive and negative to negative. Again from my understanding, it sounds like the pump will work when there is little sunlight but not to max speed until full sunlight is reached, and then slow down as the sun moves. I am thinking this might be OK because the slower the water moves through the hose, the more time it has to heat up.

Q2 - By doing number one, will I burn out or ruin the pump by not having a constant voltage running the pump as I would like to avoid running it off a battery because the battery would have to sit outside in summer temperatures that can average 105 - 110 for most of the summer.

Q3 - Any other thoughts or ideas for this project? If it simply won't work, I'd like to hear your thoughts on that too. E-bay does sell a solar panel and similar pump for $210 - http://bit.ly/W7M5Kc. However, I am thinking I would like to use the RENOGY panel because once I learn more about solar power, I can then expand with more panels and reuse this panel too for other projects.

Q4 - If it will work, should I get the RENOGY starter kit for $35 more? From reviews, I hear the controller isn't the best with that kit, so I would probably get a better controller down the road. So, should I get the better controller now or play with this one and then get upgrade later on.

Thanks in advance for any comments or thoughts!!

Russ

KenZ71 · September 2014

Re: Solar DIY Swimming Pool Heater

Years ago a friend of mine painted his pool black for the express purpose of attracting heat. Works great, extends the season a month on both ends. Flip side is during peak season he is throwing ice blocks in the pool.

So, my suggestion is experiment with different size dark objects. If above ground maybe paint the exterior?

solar_dave · September 2014

Re: Solar DIY Swimming Pool Heater

The smaller pump would be better here as a 100 watt panel will most output much less due to heat and angle of incidence. You might also need a booster on the panel to drive the pump direct but they are pretty reasonable priced.

What kind of head do you expect.

rwongca · September 2014

Re: Solar DIY Swimming Pool Heater

Solar Dave - is something like this what you are referring too about a booster - http://bit.ly/1pFywyF. If so, how does that wire in? My guess is that it would be inline between the solar panel and the pump. Yes, I think the smaller pump would be better. Also, you said what kind of head do you expect - did you mean heat? If so, I don't really know and something I might have to play with to see if even doable. I am guessing a couple of degrees. Ideally if it could raise the water temp 5-10 degrees over time that would be great. If the water was at a temp I liked, I would turn off the pump and if I felt it was dropping a bit, let it run for a few days. Even if this project doesn't work out because the temp does not raise enough to be worth it, I could reuse the panel for another project

solar_dave · September 2014

Re: Solar DIY Swimming Pool Heater

Yes something like that, others here have used similar items and probably will pipe up with their experiences.

Head is a term for how high you have to lift the water.

My solar hot water system has a nice AC controller that will only run the pump when the temperate delta between the panels and the storage is sufficient to make heating practical. I believe it is a Goldline GL30.

http://solar-components.com/gl30.pdf

rwongca · September 2014

Re: Solar DIY Swimming Pool Heater

OK thanks Dave. Do you think I can try it without that booster first and if not enough power, then add it? As for how high to lift the water at first not very high at all. Was thinking to have the hoses right on the concrete next to the pool. Yeah it will look ugly, but that will be for starters. If it works well enough, I could move the hoses on top of a patio covering. I would say that is about 10 feet high and about 5 feet away from the pool. The smaller pump says max lift is 9 ft, so probably not strong enough if/when I were to install on top of the covering. The 2nd pump says max lift of 23 ft so that might work. Phase II options

solar_dave · September 2014

Re: Solar DIY Swimming Pool Heater

I think someone with more direct DC experience needs to pipe up and let you know. I would be just guessing.

animatt · September 2014

Re: Solar DIY Swimming Pool Heater

Watch head loss(due to friction in pipe). If you plan to use just one long loop, would suggest 1.5" irrigation hose. Bare Minimum would be 1" for long lengths. If paralleling runs smaller tubing can work.
Use a head loss calculator.

To raise 15000 gallons of water 10 degrees you would need . 15000(gallons) x 8.3(gallons/lb ) x 10(delta T) = roughly 1245000 btus.

5 degree rise would be 1245000/2 =622500 btus.

Both fairly large numbers.

Depending on heat loss you will probably lose a good portion of that every day. A cover helps drastically reduce heat loss. But there are some losses you will not get away from like heat loss out of the walls of the pool.

Not sure but say you would to collect 500,000 btus on a normal day, to get roughly 4 degrees rise, Hopefully you do not lose too much of this heat at night. So pool may heat up over several sunny days.

The point here is 500,000 btus would need I believe roughly 500 sqft of Commerical panels. It is roughly 1000 btus per sqft per day. diy systems can work near performance levels of commerical systems but need some attention to do so.

You need alot of square footage. The downside is where to fit it. upside is buying commerical panels was around $2 a sqft a few years ago when I checked. pretty cheap. Obviously less square footage will contribute. But less than say 100sqft may not be worth it. 15000 gallons is alot of water.

somethings to think about

rwongca · September 2014

Re: Solar DIY Swimming Pool Heater

Thanks guys for your assistance. I've been doing some more research and I guess ideally I should hook up a timer to the solar panel/pump. So, the pump would run for about 5 minutes and flush the water out of the hose, and then stop for about 15 minutes and let the water in the hose heat up from the sun. Then the cycle would repeat 5 min or so to flush the hotter water out and bring in new water. I found this DC timer on the internet http://bit.ly/ZaNh1w. Any of you know if I can just wire this inline between the solar panel and the pump and then program the timer? Will that damage the solar panel or pump at all? Thanks.

animatt · September 2014

Re: Solar DIY Swimming Pool Heater

It would be more efficient to run a pump on a controller based on temperature difference between pool water and collector water. Let this controller turn on and off pump as needed.

rwongca · September 2014

Re: Solar DIY Swimming Pool Heater

Excellent idea animatt. Found this on e-bay -> http://bit.ly/1oNdlo8 You think it would work? Again, I connect this inline so I have: Solar Panel <---> Temperature Controller <--> Pump correct?

jcheil · September 2014

Re: Solar DIY Swimming Pool Heater

I would use this:

http://www.ebay.com/itm/CONTROLLER-of-SOLAR-WATER-HEATER-12VDC-with-3-temperatures-sensors-/261578162788?pt=LH_DefaultDomain_2&hash=item3ce7460264

I use it for my DIY Solar Water heater. Same kinda thing you are doing. I have a bunch of PVC pipe painted black, in the shape of a radiator actually, and one temp sensor goes in the top of the tank, one in the bottom, and one at the PVC collector. It automatically turns on when it senses a difference (you set that point) between the tank water and the collector water. That way it never "cools" the tank by pumping colder water from the collector into the tank accidentally or at night.

You would only need 2 of the sensors. One in the pool and one in the collector.

And I would not even involve the pool pump at all. Just get a small 12v pump and set up a totally separate loop for the heating water. Could just be as simple as two flex hoses draped into the pool. That way the pool can be heated when the "main" pool pump isn't even running. I am going to do this same exact thing with my pool here one of these days.

BB. · September 2014

Re: Solar DIY Swimming Pool Heater

Note that from a thermodynamics point of view--It is better to pump water through your collector continuously as long as the output temperature is higher than the input temperature (per jcheil's two sensor setup above).

You have less losses (higher water pipe temperatures means more losses to air/radiation). It is better to pump 100 gallons of water with a 1 degree rise vs 5 gallons with a 10 degree rise. You do not need to "cycle" the pump during the middle of the day.

-Bill

Ks Solar · September 2014

Re: Solar DIY Swimming Pool Heater

Bill makes a good point. You need lots of volume. I run my pool pump to copper tubing and fins under glass. You can find some that people no longer use. They were popular in the 70s and ended up with pinholes or other issues. I mounted mine to a shed. I run approx. 20 gals. a min. and get about 2 or 3 deg. rise. It does work but I lose a lot of heat at night so I have to run it every day which cost a lot . Also if you are trying to run a pump with solar you will have to make sure the pump only turns on once you have enough sun or you will burn up the pump.

CDN_VT · September 2014

Re: Solar DIY Swimming Pool Heater

I use a solar water heat collector and a solar panel to power the pump. Sun's out , water is pumping & if panel is heating it's a free sun win . If sun go's down , heat collection stops , pump stops .
My pool is cool most of the year , 68f , but during the summer I have seen 79f . I have been in twice or 3 times this year. Mainly it's fire protection . I have 3 pools set up , two are for fish to eat skitter larva & have water / fire plus storage for irrigation (NOW ) when the table is low.Come winter ,I;'ll have 3k gallons/day of surface water to pump.

Swimming pool is salt water for the swimming pool chlorine generator , runs March-mid Nov. Pool is above ground , with 1" blue SM foam board to get an earth break . I also have a floating heat blanket , but this year we didn't use it , I'll install it over winter .

VT

rwongca · September 2014

Re: Solar DIY Swimming Pool Heater

OK guys, I am getting close to playing around with my new setup as the solar panel is arriving today. I ended up buying the Renogy Solar Kit http://amzn.to/1uRO5lF and this pump off of ebay http://ebay.to/YPXLDD. Before I connect things together and potentially blow things up, I thought I would check in with you experts. Can I connect the solar panel itself (no controller) directly to this 12V pump as that is what I want to do? I really only want the pump running when there is sun and don't want to connect it to a battery and this will be used in an outdoor pool setting.

Any issues connecting them together directly? Can the solar panel output more than 12Volts and if so, will that harm the pump? Pump is 12V DC and 48.8 watts.

Thanks and any other thoughts are much appreciated. I'll keep you all posted on how it goes. I am going to connect the pump to 1/2 inch polyethelene tubing. Runs approx $50 bucks at home depot for 500 feet.

Photowhit · September 2014

Re: Solar DIY Swimming Pool Heater

Not sure how much flow and hence how much heating you'll be doing. Since the no load flow is Max horizonal flow rate: 21L/Min(6.5GPM)"

The panel should be over kill, it will produce more than 12 volts, typically motors will handle it okay, may reduce life and run a bit faster. I recently did something similar for a friends hydroponics. It is a smaller unit and has been working fine just wired directly to a 55 watt panel (ancient). I suspect it will be fine for it's experimental use. It has been running about a month(?) now and haven't heard of any problems. I read someone said it would burn up... perhaps brushed motors may carbonize(?) their contacts, but I think brushless motors should be fine, though it's not my end of the pool...

Have you seen the nylon pool heater panels? Pretty cheap, likely even cheaper in some off brand from Ebay

Ks Solar · September 2014

Re: Solar DIY Swimming Pool Heater

For now you could just use a timer that energizes the pump as soon as the panel reaches 12+ volts. Still sounds like the pump is too small. How many gals. is your pool?

Solar DIY Swimming Pool Heater

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