I have a heat pump - Rheem/Rudd. 10,400 gal inground. I like it. I also live in NJ - Northern and have lots of trees and not too much sun. We open the pool, turn on the heat pump and keep it at 77 all season. Once it heats up it rarely goes on. Hard to tell the cost since I have a 1.5 HP pump running ten hours a day.