Does battery technology need to be on an exponential curve? We already have electric car batteries that can power your home for a good long time. Note that a battery for a home is cheaper as there is no weight restriction, unlike with a car. You can use old refurbished batteries that are no longer suitable for cars.

On the grid scale, a pumped hydro facility can provide energy storage for thousands. Energy storage is technologically a solved problem, it’s just not equally distributed yet.