Hello ..
See this article describing an application to redirect excess solar in my home's existing electric heaters.
It uses Shelly 1PM, Shelly Plug.
https://pboudalier.medium.com/maximize-your-solar-to-keep-your-home-warm-part-1-14322a0adbb7
Also an update after one year of using the app, adding Shelly I3
https://medium.com/@pboudalier/solar-into-heaters-a-year-later-bb73c7a1aeb7