20 x 40 IG vinyl here (30k gals). About 70 miles north of NYC. Opened after Easter, was at close to 80 before 2 weeks of clouds and rain put us back down to 65. Now we are at 86 and the solar runs about 2 hours/day. We typically get a 2 to 3 degree per day rise using a solar cover.

We have about 55% coverage on an East/slightly northeast roof. So far, we are thrilled with the system. Our neighbors are all swimming in low 70s due to fuel costs!!