[karussell]

The problem with thermal solar panels is that you can use its heated water only if it gets warmer than the water in your system, which is not always the case, especially in winter.

Compared to nearly 100% usable energy from normal solar panels.

Furthermore if you have a heatpump you can convert this electric energy into heat energy with a factor of >3 (COP).

[Marsymars]

Yeah but if you're in a northern climate your solar panels are only generating like 10% of their summer capacity in the winter anyway due to sun hours/angles... winter is just tough for capturing solar energy in general.