Well Norway (Hydro), Sweden (hydro and nuclear) and Finland (Nuclear Wind Hydro) all have cheap electricity which seems to be the main driver for adoption.
Sweden used to have very cheap electricity. That's why there are so many houses with electric radiators. Far more expensive now.
That is why so many houses here now have air-to-air heat pumps. That is by far the cheapest way to improve heating in an old house with only electric radiators and no existing water heat pipes.
Hrm. It might be cheaper than in Germany but its not cheap in Sweden except for the most nordic parts (hydro).
South Sweden - i think the prices are more on par with germany.