How long is the payback period for a geothermal heat pump system?

To figure this accurately, you must know how much per year you’ll save in energy costs with a geothermal system and the difference in costs between it and the alternative heating system and central air conditioner. To calculate your return on investment (payback in number of years), divide the annual savings into the additional cost. Keep in mind that energy savings is only one of the many benefits you receive from a geothermal system.