Hey. This is interesting for me.
I now have a 6 kWh panel that are on grid for reverse metering.
Then I replaced the inverter with phocos one so that it will work without batteries in off grid mode.
I have thought quite a bit about water batteries, I want to install 200-400 Litre water solar heater so that my electric energy is reduced even more.
No batteries yet because they cost a fortune.
My idea was to heat say 500 Litre water tank in my basement with solar water + solar electric and pass that water through the central heating piping through he home but installer tells me the heat won't be there in this "water battery".