How much electricity do heat pumps use (and how do I generate that in the winter) ?is(are) the question(s) I'm asking myself. Here in N. Germany, in my old farmhouse in the country, I'm likely to use my current combo of oil/wood heating, fluffy clothing and eating lots to keep me warm until they give me a grant to change things (not holding my breath, my state has nothing like that right now). (I'm lucky in that my body mainly turns excess food straight into heat rather than insulation!).

I've got room for ground source, and don't need massive heat (but the place is dreadfully un insulated nor can it be easily or even advisably done. Damp and rot if you (very expensively) try to make old places into sealed boxes....