Concept

Photovoltaics and other renewables are not gaining traction like they should be because of intermittency - what do you do with PV if there is no sun at night?
Batteries are expensive. To store enough energy, say in winter when there is little sun - for 5 days - would require a tremendous amount of storage. About $50k [1]
But here's how we do it - store the heat in thermal mass - water - not battery storage.
Water is less expensive than batteries. In fact, about 100,000x less expensive per kg. [2] - 1/20 cent vs 2500 cents
What if we just store water? Yes!
You can use a heat pump to heat water. Hot Water Heat Pump costs $6k for 60k BTU. More than enough for hot water, whole house heating.
How it works: during day, heat pump uses PV energy to heat water - or cool it in summer. This water is stored in IBC Totes as a $50/pop solution.
A heat exchanger extracts the heat or cool from the water - blowing it through the house
That's it.
If this is connected to underground tubing - you have just created a geothermal cooling system that can cool in the summer as it is cool underground - and you don't even need to run a heat pump to do the cooling - so you use 25x less energy.

Try 2

Detailing the scenario, 20 sq meters of IBC totes 2 high, raised only 30C from 20-50C - or in the negative direction in summer - stores heat/cool for 12 days, and takes 6 days to produce that heat with PV! 1 MWhr of heat stored.

https://chatgpt.com/c/685b1c5e-83c8-8010-a0e4-bbd8923c8845