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Thread: How many solar panels?

  1. #1
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    How many solar panels?

    I am trying to determine just how many solar panels we need and know the following:

    1. Our pool is 27' so I estimate the total water surface at 572 feet.

    2. We are planning on using the Fafco 4x20 foot panels.

    3. We are limited in space (see our current backyard configuration and Spring landscape plan project below)

    [img]



    Originally we were planning on three panels, but Fafco's website recommends two panels and we have limited space. We have tried to figure out how to incorporate it into our landscaping project, and someone recommends the attached:



    We are open to any and all suggestions! Thanks!
    Wil-Bar 27'x54" Quest AGP
    Hayward 1HP Powerflo Pump
    Hayward 256 T Swimpro Sand Filter

  2. #2
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    Re: How many solar panels?

    A few questions:

    What state do you live in?
    What start/end season do you want?
    What water temperature do you want?
    What direction will the panels face?

  3. #3
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    Re: How many solar panels?

    We live in northern Illinois (suburb of Chicago) and we really aren't as concerned about extending the swimming season as raising the temperature. Ideally we'd like the water temp to be above 80 from June through August. The panels will be facing to the south (20 degrees or so as recommended).
    Wil-Bar 27'x54" Quest AGP
    Hayward 1HP Powerflo Pump
    Hayward 256 T Swimpro Sand Filter

  4. #4
    Senior Member linen's Avatar
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    Re: How many solar panels?

    Not sure if this will help, but I will share my "first year with solar" memories. I am in the twin cites (mn) and I have 4 2'X20' panels facing southwest heating (sometimes) a 21' foot pool from about noon until early evening (I have shade on panels until noon typically). Agian, I have only been running them 1 season. From my poor memory...I started last season with 2 2'X20' panels and really struggled keeping the pool above 70 degress starting in early/mid June. Added 2 more 2'X20' panels at the end of June which I was able to keep the pool above 80 degrees in early July. By end of July/early August I was not using the panels much, since the water was warm. Early august started using the panels all the time again and by mid august struggled to get consistently above 80. In early september it bounced around but I struggled at times to stay above 70. By mid september somedays we could get above 70, sometimes not. End of september, bouncing around 65. Had a brief heat spell in early October where with diligence we got to 70 for two days! It was downhill till there...hence I am contemplating adding 4 more 2'X20' panels (or if I can find a good deal 2 4'X20' panels...where are finding yours?). This would give me a total area of 320 ft^2 and my pool is ~350 ft^2. Having equal solar to pool area ratio tends to work best at northern clims. Since you are slightly further south, and may not have shade in morning, you might get away with less.
    TFP Moderator who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

  5. #5
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    Re: How many solar panels?

    If you only want above 80 F during June, July and August, then it should not take too much solar to do that. I think that (4) 4 x 20 panels would probably be a required to give you good consistent results.

    What are the typical pool temperatures during June, July and August?

  6. #6
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    Re: How many solar panels?

    Thanks James and linen. Last year we were consistently above 75-78 for those three months, and above 80 for a lot of it. Last year was an exceptionally hot summer though, and it was the first year we had the pool. Any thoughts on the diagram of creating a roof over half of the deck to place th panels on?
    Wil-Bar 27'x54" Quest AGP
    Hayward 1HP Powerflo Pump
    Hayward 256 T Swimpro Sand Filter

  7. #7
    Senior Member cramar's Avatar
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    Re: How many solar panels?

    I read a lot of people that say the square footage of your solar panels should be the same (ideally) as the square footage of your pool.
    20' X 54" Sharkline Matrix Resin AGP, 9400 Gallons, Sta-Rite 1 HP Dynamo Pump, 150 lb Pentair Sand Filter, Gorilla Pad,
    Foam Cove, Taylor K-2006 kit, BBB method, 8'X20' Fafco Sunsaver Hard Plumb, DIY Fountain, Margarittaville Fiji


    My Build: one-man-one-pool-and-one-deck-agp-pics-t37172.html
    My Build 'To-Do' List for other DIY'ers: my-pool-build-list-t40249.html?hilit=list

  8. #8
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    Re: How many solar panels?

    That is nearly impossible in my situation. The best i can do, space-wise, is 3 panels which total 240 sq ft. My only other option would be to mount them on our house roof, but we live in a two story house and the pool is approximately 75' from the house. This would be DIY project and the roof is way too steep for me to go up on. Sounds like another heat source (maybe a heat pump) might be a better option?
    Wil-Bar 27'x54" Quest AGP
    Hayward 1HP Powerflo Pump
    Hayward 256 T Swimpro Sand Filter

  9. #9
    Senior Member linen's Avatar
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    Re: How many solar panels?

    You will get some benefit with that area. Like I mentioned above,I was running with 160 this summer and we did benefit. I would think you would too.
    TFP Moderator who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

  10. #10
    Senior Member cramar's Avatar
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    Re: How many solar panels?

    Ya, don't confuse "ideal" with "acceptable", I don't have enough room to get the square footage of my AGP but I'm still going to put up 2 panels this summer.
    20' X 54" Sharkline Matrix Resin AGP, 9400 Gallons, Sta-Rite 1 HP Dynamo Pump, 150 lb Pentair Sand Filter, Gorilla Pad,
    Foam Cove, Taylor K-2006 kit, BBB method, 8'X20' Fafco Sunsaver Hard Plumb, DIY Fountain, Margarittaville Fiji


    My Build: one-man-one-pool-and-one-deck-agp-pics-t37172.html
    My Build 'To-Do' List for other DIY'ers: my-pool-build-list-t40249.html?hilit=list

  11. #11
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    Re: How many solar panels?

    hello all
    Each panel of 4X20 equivalent to 10 cubic meters and therefore you have to begin to calculate the how many solar panel you need depending the amount of cubic meters are in the pool.

  12. #12
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    Re: How many solar panels?

    We are in southeast Wisconsin, along the border. We have a 27 foot round and 4 2x20 mats. We have ours on the ground running paralell with the veggie garden. I keep black landscapers fabric under them. We have found 4 mats to be great, they definately increase the heat several degrees. We also use a solar cover as we are in a very windy area. The mats get atleast 8 hours of sun just like the garden. Last summer in this area was horrible, we hardly used the pool at all but weather is weather. We considered adding 2 more mats this year but have since changed our minds as the pump would not handle it. Fortunately space is not an issue for us. The mats are actually about 20 feet away from the pool but we have trenched and this year will bury our hoses as they run to the mats.
    27 ft round 52" wall
    Cartridge filter
    Above Ground
    2 hp Hayward pump
    Using 2 2x20 solar panels

  13. #13
    Senior Member cramar's Avatar
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    Re: How many solar panels?

    Good to know, I'm adding the same amount of panels to a 20' AGP and I'd say our climate is very similar to Wisconsin.
    20' X 54" Sharkline Matrix Resin AGP, 9400 Gallons, Sta-Rite 1 HP Dynamo Pump, 150 lb Pentair Sand Filter, Gorilla Pad,
    Foam Cove, Taylor K-2006 kit, BBB method, 8'X20' Fafco Sunsaver Hard Plumb, DIY Fountain, Margarittaville Fiji


    My Build: one-man-one-pool-and-one-deck-agp-pics-t37172.html
    My Build 'To-Do' List for other DIY'ers: my-pool-build-list-t40249.html?hilit=list

  14. #14
    Senior Member dmanb2b's Avatar
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    Re: How many solar panels?

    You'll want the 3 panels. I run 2 on a 24 ft pool in upstate NY and have no problem keeping the water temp at 80+. The key is using a solar cover in the evening to cut down on heat loss. 2 panels are still better than none, but on a 27' pool I would opt for at least 3.
    24'x52" AGP (13,500 Gallons), Intex SWG, (2)Solar Bear 4x20 panels, Hayward S220T Filter, 1/2hp Pentair Superflo

    Pool School, TFTestKits, Pool Calculator

  15. #15
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    Re: How many solar panels?

    Quote Originally Posted by shlomi
    hello all
    Each panel of 4X20 equivalent to 10 cubic meters and therefore you have to begin to calculate the how many solar panel you need depending the amount of cubic meters are in the pool.
    I want to note that also it depends on the water flow rate, if you have solar panels valve before the heat system you can set a relatively slow pace and warm up faster the water/

  16. #16
    Senior Member linen's Avatar
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    Re: How many solar panels?

    Quote Originally Posted by shlomi
    I want to note that also it depends on the water flow rate, if you have solar panels valve before the heat system you can set a relatively slow pace and warm up faster the water/
    In general, solar panels are more efficient at higher flow rates. Ideally you want a high enough flow rate where the water temp is just slightly higher going out then in. When operating your, panels should feel cool. The only other reason to run at lower flow rates is if you flow rate is above the rating for the panel or if you are cavitating.
    TFP Moderator who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

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