It really depends on your starting point. If you have a perfectly serviceable means of heating that you are happy with, then it's a straightforward cost analys

It really depends on your starting point. If you have a perfectly serviceable means of heating that you are happy with, then it's a straightforward cost analysis (cost of consumables for the current heating method vs cost of electricity for the heat pump). I can only give an example that applies to my situation: previously I burned ~2300l of diesel which cost around 2300EUR for the previous heating season. So the yearly energy consumption is about 24MWh (combustion heat of fuel multiplied by efficiency of the furnace of ~94%). If I were to install air source heat pump, it would require about 8-9.6MWh (COP =2.5-3) of electricity per year (4000-4800EUR at the current fixed price offering from my electricity supplier of ~500EUR/MWh). If I were to install a ground source heat pump (COP of 4.5-5.5), expected electricity consumption is between 4.3-5.3 MWh or ~2200-2600EUR/yr. If I were to power the ground source heat pump using the electricity generated by my solar panels (Latvia currently has 1:1 net billing system, but there is a grid cost of ~50EUR/MWh) the expected yearly heating cost is ~210-260EUR. At the previous electricity cost of ~100EUR/MWh, air source heat pumps for not-so-well insulated houses might be attractive option- but not at the current prices in Europe. When I did the calculations this spring, the break even time for heat pump + solar installation was ~8 years (based on fuel and electricity costs at that time). Right now it's around 4 years (and I might even get ~40% of the investment from a government clean energy incentive programme). However, I have to operate under assumption that a crazy dictator of a neighboring country doesn't decide to invade and wipe my house off the Earth...