I have geothermal heating and solar panels on the new home I bought after getting divorced. I still pay the heating and electric on the old house my ex is in as well so I get to see the difference these units make on my bills.  My new home is slightly smaller than my old one, 1900 sq feet vs 2300 sq feet.  Final conclusion, bills for both homes are almost identical with my old home costing roughly $75 a month more.  Considering that the old house is larger, older, and no where near as well insulated it pretty much tells me what my investment in "green energy" is worth.