In my house, most of the energy needed is heating or cooling.
So why not do most of my energy storage in, say 5 or 10, tanks of 1000 litres of water. Properly insulated.
They could be in the basement or a room, where the wasted heat would benefit the house.
When you need heat from the storage you send water through the coil of tubing in the upper part of the tanks.
When you have heat to store you send hot water through the coil of tubing in the lower part of the tanks.
Same tanks might be of use storing cool water during summer...
Tanks could be divided by temp, so you have tanks at, say 30, 60 and so on, giving best use of your heat.
Is this crazy?
Cheers, john, Denmark