Do solar panels really work?

[jmjbj_h]

I am on the fence with this one. I have a 16x32 IG which roughly equates to 512 sqft. I have to minally cover 1/2 of the square feet which will bring me to 256. I can only fit about 240 sqft of Sungrabber on my east facing exposure roof. It gets quite a bit of sun due to the pitch and lack of a lot of trees. I don't want to invest on this one if it really isn't going to make a big difference. What do you all think?

[NWMNMom]

We have 4x40 feet of panels and live in a very northern area with cooler nights. Using the solar cover to keep the heat IN really helps but the thing is that just using the panels listed above, my pool will stay right about 85 and above for most of the season. Hooking them in immediately raised the water from the mid 70s to the 80s within a couple days of the pump running from appx Noon - 7pm. We had a lot of days we had to run the panels at night to cool the water down as 95 and over does not feel refreshing. End of last summer we ran on just 3 of the 2x20s due to damaged panel (replaced now) but had water that stayed over 80 and usually over 85 until the nights hit the 40s again.

So the short answer is YES, it will help. If 240 is all you can fit, then go with 240 sq ft.

[jmjbj_h]

I was considering 3 (4x20) panels. So you are saying that you get a really good boost from just 2 (4x20) panels. Your pool is bigger than mine, the only difference being that it is above ground. I wonder if that will make a difference?

[tphaggerty]

Biggest downside to solar is recovery time. Even 1/2 coverage will get you into the 80s with decent exposure. I boosted my solar from about 55% to well over 75% and saw a 10 degree rise on one day, something we never got before.

But, basically once you pay for the panels and plumbing, its free heat. If you have been swimming with no heat, you will LOVE your solar.

[CarlD]

You'll be amazed at how much even two panels will help. The figuring is based on the surface area of the pool, which really makes no sense. After all, you have to heat a volume of water, not an area. All 20,000 gallon pools (for example) should require aproximately the same amount of solar panels. I/Gs may get away with less as the surrounding ground becomes a heat reservoir.

Of course, the more surface area you have, the more heat you lose to convection. But with a good solar cover, you reverse that: The more surface you have the greater the greenhouse effect to heat your pool.

[tphaggerty]

Not to be picky, but surface area is actually an OK benchmark for figuring out how much solar, because it *generally* trends the same as pool volume, within reason, at least for IG pools.

For AG pools that don't have a deep end, I agree that volume makes more sense. But, if you use the area calculations for an AG, you are probably oversizing a bit, and as all of us in the solar world know, bigger is better (if you can afford it and have the space!!).

[cleancloths]

I just installed a pair of 2' by 20' panels (80 SqFt total) to supplement the heatpump I have in my 20' x 40' IG (800SqFt surface). I realize that this is only 10% and that to provide all the heat needs I would need 400-600 sqft. But I am only looking at this to provide extra heat and save me some utilities. So far it seems to be doing a reasonable job. I figure this setup can add about 0.3 degrees per day to the pool. While that is not a huge number, it does come out to over two degrees per week which is not bad for almost no cost. The entire setup cost me under $200 for the panels and piping.

[CarlD]

I have a different take (but similar to CleanCloths): ANY solar panel is probably going to help if installed correctly, even if only a little. If it's not enough, you can add another panel, and another, until you are satisfied. I have used panels that barely had 1/5 the surface area of the pool (33x18 oval using 1 4x20 and 1 4x10 panel), only got 6 hours direct sunlight a day in downstate NY, and STILL had significant results--the pool went from 78-79 all summer to 84-85 --from chilly to comfortable.

Of course, you CAN turn panels off, but why spend $200/panel plus plumbing for more than you need?

[simsjim]

Dumb Questions about set up

Does the addtion of solar panels create the need for larger pump - because of the addtional head?

Can I bypass (with a valve) the water's path through the panels if my pool temp is where I want it to be? - I think i know the answer to this but just want to be sure.

Is the head calcualtion any different since I would be going vertically up to my roof to reach the panels? IE can a WhisperFlo 3/4 HP EE pump handle the addtional head of the panels?

I am assuming ALL of the routing to/from the panels happens AFTER the filter just like in more 'conventional' heater set ups. Is this true?

I am curious, because I only need mild water temp warming to extend my season and add just a few degrees during the hottest months. I achieve good tempratures in late June through Aug with the use of a solar cover, but to eek out an extra month or two of swimming could be worth the investment in solar (but for me fossil-fuel heating is not the way to go).

[JohnT]

Dumb Questions about set up

Does the addtion of solar panels create the need for larger pump - because of the addtional head?


It usually doesn't, but in most installations, a bypass valve is installed to allow routing some of the pump output past the panels to maintain reasonable pressure.



Can I bypass (with a valve) the water's path through the panels if my pool temp is where I want it to be? - I think i know the answer to this but just want to be sure.


The bypass valve mentioned above can perform this function as well.



Is the head calcualtion any different since I would be going vertically up to my roof to reach the panels? IE can a WhisperFlo 3/4 HP EE pump handle the addtional head of the panels?


Probably. Depends how high the roof is among many other system specific variables.



I am assuming ALL of the routing to/from the panels happens AFTER the filter just like in more 'conventional' heater set ups. Is this true?


Yes, but don't put the panels after a chlorinator.

[cleancloths]

Assuming the pump can initiall lift the water the height really does not come into play as you are pumping up but the falling water acts like a siphon pulling down on the pump. If you draw a box around the entire system you are only raising water from the skimmer level and injecting it back at the surface for a net rise of about a foot or less. You do have the friction loss in the added piping but it should not be that big a factor. I put in 1.5" pipe for my two panels, way overkill but causes almost no head loss.