It is always good to look at current grids and prices to see how things are. In Sweden, the sunny days around may-juli have made those months almost free. Solar

It is always good to look at current grids and prices to see how things are. In Sweden, the sunny days around may-juli have made those months almost free. Solar and the reduced need for heating, in combination of very limited use of AC, means that you don't need much beyond solar, wind and some base load from nuclear/hydro power. I contrast, 75% of the yearly energy bill comes from the 3 winter months, where solar has around 10% (and often less) of the generative capacity. This mean that the energy bill is very variable, and bad weather during those few critical months will results in unreasonable bills (as in bankruptcies and voters that ask the government for bailout). Under market forces, the electric company have no quarrel in sending people a bill that is 12 times the average month for a single month. There is also very luke warm interest in reducing the cost for the consumer by building out storage. The economics has so far not been that great outside of using government subsidizes, and as northvolt demonstrated, not that interested in using loans when the subsidizes run out. That said, the Finish project of storing hot water for district heating looks like one of the more interesting storage solution. They are also investing into nuclear, so it seems like time will show how the economics will pan out. Heat exchangers are very effective at generating heat for district heating, so the heat storage has some steep competition.