zlacker

A heat pump gets more heat from a given amount of electricity than if the electricity is use for resistive heating. So the ideal design is solar cell + sodium battery + heat pump.

>>belvie+(OP)
Also when the temperature differential is lower, so ideal might be solar -> battery (to time shift to warmest outdoor temperature) -> heat pump -> thermal battery (to time shift to when you need heat).

Does seem like a lot of added complexity (and likely machinery cost) though.

>>gpm+ax3
The question is would it cost less over the long term than any other solution. My intuition is it would, at least for a lot of use cases, but it would need to be put into practice and studied to see if this is actually true.