We had an 18' round AG in the past and got by with one 2x20 panel from May - the first weekend of Sept in far northern Minnesota. The water stayed about 82-88 degrees all the time except mid July when it went up into the 90s. We are installing an 18x33 AG which will use one 4x20 and the 2x20. I don't think we will have a problem keeping the water warm unless we have an unusually COLD or sunless summer.

With a 24' AG, I would think that the same config we have or 2 of the 4x20s should suffice, especially as far south as you are. You MUST have a solar blanket to keep the heat in. All told with the blanket, less than $500 expense there. Sounds like your pool guy wants a nice commission to pay for the rising gas prices!