I just purchased a pair of 2' x 20' Sungrabber panels on e-bay. They seem good and have a 10 year prorated warrantee - but they does not include things like freeze damage due to not draining. The were cheap enough - I paid about $130 for them. They seem to work well. I just have them on the ground as my roof is covered with a 10KW PV electric solar system.

I am using these just to supplement my heatpump for the pool. But I have no desi to ever see the pool over 84 degrees, I would have to start calling it a large bathtub rather than a pool if it ever hit 90.