Solar Panel Question

[CarlD]

Yup. Depends.

My parents had an 18x33 oval A/G that held almost 14,000 gallons. The site only got 6 hours direct sun a day. They were miserable because the pool never hit 80 all summer. Then I installed 2 panels, a 4x20 and a 10x20. On only six hours a day, using 1/2 of what is "recommended", the pool stayed at 84-85 degrees all summer! They were thrilled!

You don't need the "recommended" amount of panels--you can always add in more, easily, if you find what you have isn't sufficient. Had Mom and Dad had 12hours of direct sun a day, the 4x20 panel alone would probably have been enough.

Since I had their panels on the ground, they kept working after the sun passed. The ground acted as a heat sink and kept putting heat back into the panels. Remember: As long as the water from the panels is warmer than the pool, it's helping. Even if it's only one degree warmer, it's adding heat and BTUs are what you need, not raw temperature.

[matt4x4]

We installed ours last year (1/3 of what we need optimally), now mind you, we had an extremely hot summer, but running them during the daytime kept our pool at or near 90 degrees all summer and extended our season by a total of a month.

[kaybinster]

The panels take up a lot of space, and create a good deal of backpressure so your pump will not circulate as much water as it is supposed to. Further, an IG pool is going to require a lot more surface area. You really need about the same surface area in panels as your pool has, if not more. Further, they won't do much for you in the early spring and late fall when you really need the most heating. Heck, my heating needs during July and August in NJ are almost zero anyway with a cover on the pool at night.

What I have is an electric heatpump which extracts "free" heat out of the air and dumps it in the pool. I have PV solar panels on my roof which generate electricity. My 10kw system generates about 12,000 kwh per year. Here in NJ there is a great rebate program on solar electric systems where the state pays about 60% of the system cost. When I installed mine they were paying 70%. I figure the system will pay for itself in just under 4 years, after that its a cash cow.

I have time-of-day metering for my electric, so we pay higher rates during peak periods and low rates at off peak time. I run the heat pump at nights and on weekends when power is cheap. The PV system spins my meter backward during the day when power rates are high. This is probably the most efficient overall system to have.

[matt4x4]

Yes, space is an issue, but I have to disagree with the system not warming your pool early in the year.
We were swimming in mid May last year - Ontario - Canada - temps were 85+, and this with only 1/3 of the panels we should have.
I started up my pool in early to mid april, put it on a timer to take advantage of the daylight hours to collect my heat, did not run it at night since you will remove the heat you gained faster.
Sunlight that hits the panels will convert to heat energy, whether the sun is low on the horizon or not, yes, it's not as efficient as mid summer, but you still get heat, and judging from what my system provided last spring, it's plenty, as long as you put your solar cover on at night to avoid losing the heat you gained during the day - if you forget the solar cover 1 night, you're probably looking at 3 days to recover what you lost.
Same goes for the fall time, all in all we gained at least 4 weeks of COMFORTABLE swimming.

[kaybinster]

I guess it all depends on what you consider early! While you call mid May early, I call it very late. I just came in from pressure washing the winter cover on my pool in preparation for removing tomorrow and starting everthing up. I plan to be swimming in a week or two in nice warm 79 degree water

[matt4x4]

Well, I guess I could also go outside and use my pool too, except i would be skating on it!

[NWMNMom]

I would be surprised if the ice is off in May here (NW Minnesota) this year - long cold winter. We only have a 4x20 and a 2x20 for our 18x33, so I'm hoping that will bring our temps into a comfy range. Last year we had an 18' x 48" round pool with just the 2x20 and it kept it at about 82 average (except end of July when we had to run it at night to cool it off!) I guess we could always order another panel if needed. Its FREE heat, can't sneeze at that.

If its normal temps (whats normal?) this year, is it only wishful thinking that the 2x20 with the 4x20 panels will be enough to keep our new pool warm?

[waterbear]

You really need about the same surface area in panels as your pool has, if not more.

I've done some research into solar heating since I am considering adding it to my pool in the next year or to to suppliment my heat pump. The sq footage of solar panels needed is dependant on the direction of exposure with a southern exposure needing about 70% of the sq footage of the surface area of your pool, western needing about 80-85%, eastern needing 100% and northern exposure not being recommended. Of course these are just general guidelines and not gospel. One source I checked even said that a SSW orientation of the panels would be the most effecient needing only 65% of your pool's surface area.

[pedsrn]

We finally got our panels installed yesterday, hubby had a time getting the right size fittings because ours had to be placed about 50' from the pump.

A couple questions:

1. Do I just need to turn them on when the sun is directly on them or is any daylight okay?

2. My pump pressure raised about 4 psi when we connected them up, is this okay?

TIA!

p.s. I was amazed at the difference in the warmth of the water coming from the return.

[CarlD]

OK,
I have a very simple answer to whether you should run your panels or not:
If the water coming from the panels is warmer than the pool, by even the slightest amount, you should run them. BTUs are what you want, temp is less important. ANY warming of your pool is A Good Thing, and every BTU you can grab from the panels brings you closer to your target warmth.

A 4lb increase is not much at all--be happy!