@ChristopherNoyesRoberts @BrentSullivan Geoexchange systems (or surface geothermal) actually uses heat from the sun stored near the surface of the earth (say the first 1000 or so feet). A geothermal heat pump is about twice as efficient as an air-to-air mimi split. I have a solar array and geothermal heat pump. From Feb 22-Mar22, my utility bills in Mid-coast Maine totaled $10. Over the course of a year I pay net zero dollars to heat and electrify my 3000 sq ft home. #ClimateChange