Quote Originally Posted by mohawk View Post
I've looked through the post here and on web sites and I'm not sure on how many solar panels we will need. We have a 30' rnd pool-not 27' like I thought earlier, it was a long winter. I want to run 2-4x20 panels side-by-side down the length of the deck. Do you think 2 would keep the water in the upper 80s ? Can you run the panels side-by-side(length to length) with ease or am I going to have alot of plumbing on the ground? Does this make sense to you-I'm not sure if I'm explaining it right.
Let me see: 30' round is 707 square feet. I think you need at least one more panel.

However, the good thing is you can put in 2 panels, see if they are enough, and, if not, add another. My parents had the same ratio of pool area to panels, only got 6 direct hours of sun a day and the water stayed in the low 80s. You'll need to keep the panels on the ground, because they will heat the ground, and then the ground will, after the sun passes, warm the water some more. Remember: As long as the water from the panels is even 1 degree warmer than the pool it's adding BTUs--heat energy. You'll also need to be good about using your solar cover when you aren't swimming.

If you mean can you hook the panels in parallel rather than in series, the answer is not only "Yes" but that it's better that way. If all the water must first go through one panel, then the next, it sets up back pressure and makes your pump work harder. Your flow of water through the panels will be less, so it won't heat your pool as effectively. But in parallel, resistance will drop and more water will flow.

A few years ago I split my system from strictly series (one panel after another) into 2 parallel systems. My water warmed up far faster because I got double the flow. It worked even better than I hoped!

Remember: the more water you flow through your system, the warmer your pool will be. Basically, if your panels are cool to the touch on a blazing hot day, or at least don't burn you, they are doing their job efficiently.

There are lots of technical reasons why TOO fast a flow loses efficiency, but for most people they really do best by moving as much water through their panels as they can. "Letting the water heat up" with a slower flow SEEMS to make sense, but, in fact, is wrong.

Remember: the more BTUs you can add every hour, the more your pool will warm. It's not temperature--you just want the panel water warmer than the pool. A match burns at around 750-800 degrees but a 5 gallon bucket of 90 degree water will add FAR more heat energy to your pool than the match.