Or plug them into a UPS that charges when it's free but you can run them whenever.
Batteries are massively more expensive. Thats why the utility companies are just giving consumers free power over building their own grid scale batteries.
A tank of water is cheap, it’s just not possible to distribute hot water over the grid. But it’s very realistic to store it locally and use for heating and cooling. Which is the bulk of power usage anyway.
There are never designs coming into the market that support only, say, the fridge, and have the software to be time of day use metering aware, that won't totally break the bank.