What is the recommended size solar system for a 20x40 pool?

MattE71

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Jun 7, 2013
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#1
Hi guys!

We are considering building a pool and having the solar system as the main source of heat for a 20x40 pool. I know it will shorten the swimming season but we are considering installing propane or a heat pump the following year. What would be the perfect square footage for a solar system? I just don't want to cut myself short, that being said, can you really have too much? The pool builder wants to use Enersol. Is this a good brand? Seems pricey!

Thanks!
 

JasonLion

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May 7, 2007
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Silver Spring, MD
#2
It very much depends on where you are located and what your goals are. Do you want to extend the season by one month on either side, or two, or swim all winter, or just get the water a little warmer during the summer?
 

bobby1017

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Feb 2, 2011
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Petaluma, Ca
#3
As said there are allot of variables. When i was installing I heard that having the same sq footage of panels as the pool surface is recommended. I have 325 sq feet of helicoil panels for my 20' x 40'. This year it got above 80 deg by 4-14 and dropped below 80 deg on approx 11-1. In between then it stays at between 84 deg and 88 deg depending on the time of day. More panels will be able to keep the pool warm while running less hrs, and extend the season a little more, but no amount will keep it swim able through the winter. ( Maybe in the tropics).
 

MattE71

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Jun 7, 2013
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#4
We are in the Pacific Northwest near Seattle - Vancouver region. We have a lot of sun in the spot where the panels would go. We would just use the pool in the summer months and not in the spring or fall. Just hoping to get the pool as warm as possible in the summer but as cost effective as possible. Is the Helicoil a good brand?
 

bobby1017

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Feb 2, 2011
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Petaluma, Ca
#5
My panels face south and get direct sun for approx 9 hrs per day, I think the theory is the panels will raise the pool temp by 15 / 20 deg over the average daily temp, but you do need a cover to help retain the heat, without that your temp gains will be less.


From my experience Helicol has good panels but there are others that are just as good also.
 

MattE71

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Jun 7, 2013
79
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#6
Yes the plan is to go with a clear solar cover. I also think that my area would see sun 9+ hours a day in the summer months.
 

pooldv

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Aug 10, 2012
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#7
You should also consider getting a solar controller to make sure it is only heating and not cooling. Rain and clouds can cause your solar panels to cool the pool. Our panels were much more effective this year with the controller added than they were in prior years. I don't have any data, and it varies day to day and month to month anyway. But, overall our panels add a lot of value to our swimming and the controller made it way better. We like our pool warm, 85 and up. Also, do some searches in TFP, there is some good info here in old posts. Isaac-1, in particular, has posted quite a bit of good info.
 

MattE71

Well-known member
Jun 7, 2013
79
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#8
You should also consider getting a solar controller to make sure it is only heating and not cooling. Rain and clouds can cause your solar panels to cool the pool. Our panels were much more effective this year with the controller added than they were in prior years. I don't have any data, and it varies day to day and month to month anyway. But, overall our panels add a lot of value to our swimming and the controller made it way better. We like our pool warm, 85 and up. Also, do some searches in TFP, there is some good info here in old posts. Isaac-1, in particular, has posted quite a bit of good info.
Thanks for the info! This did cross my mind! So you mean with a controller like a cell phone app? So you can turn it on and off when your away?
 

bobby1017

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Petaluma, Ca
#10
You should also consider getting a solar controller to make sure it is only heating and not cooling.
The controller compares the pool temp to the temp of the panels and turns the system off and on automatically depending if there is heat available. Definitely helps to maximize the time the system is heating.
 

pooldv

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Aug 10, 2012
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#11
Right, we have a Pentair Solartouch solar controller. It has a temp sensor on the roof and a water temp sensor. If the the roof temp is 2 or 3 degrees above the water temp it will open the valve to the solar panels and turn up the speed on the variable pump. If it gets cloudy or rainy and the panel temp drops below the water temp it will shut it down so it doesn't cool the water. Good stuff. And it costs less than 300 bucks!
 

MattE71

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Jun 7, 2013
79
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#12
Right, we have a Pentair Solartouch solar controller. It has a temp sensor on the roof and a water temp sensor. If the the roof temp is 2 or 3 degrees above the water temp it will open the valve to the solar panels and turn up the speed on the variable pump. If it gets cloudy or rainy and the panel temp drops below the water temp it will shut it down so it doesn't cool the water. Good stuff. And it costs less than 300 bucks!
Wow that is cool! Yes this sounds like a no brainer!!! I didn't think it was that easy? I thought you had to monitor the temp on your phone and then turn it on using your phone?

Looking at a pool like yours? Were looking at a steel 18x41x25