I have a 6700 gal fiberglass pool. Just bought two of the Sungrabber 2' x 20' aboveground pool solar panels and installed them this past weekend. I am impressed with the results so far. The weather this weekend in VA was party cloudy, in the upper 70's. I consistently got a 6 degree increase from the pool temp on water coming out of the panels when sun was on the panels. Yesterday at peak exposure, the output was 90 degrees.