We installed a Heat Pump in the pool less than a month ago and so far have been VERY pleased with the results. We haven't however got our first bill yet with it in use. We started off with the water temp at about 80° and it ran 24/7 for about 2 days with the outside temps averaging about 75° before it hit our desired water temp of 86°. After that first "jump" however it's rarely ran to maintain the temp of 86°. For the most part, with using the solar cover, it may run 2-3 hours per day tops with our current 80° temperatures. I would suspect that living further north than us you'll run into much colder temps at times thus likely swaying the advantage towards Natural Gas, but in the end your biggest help will already be in place......the automatic cover! Regardless of which you pick, this cover will save you a good bit of cash on heating. You'll enjoy the heck out of it once it's in place.