Another way: Have a standardised battery pack, that can see duty in a multitude of applications, for example: part of a home solar installation, or in a car.

Another way: Have a standardised battery pack, that can see duty in a multitude of applications, for example: part of a home solar installation, or in a car. Have a control system that allows multiple batteries to be combined, in a hot swappable manner, within a single installation. Advantages: 1) Economies of scale allow lower battery price, since the same pack is used everywhere. 2) Common form factor allows batteries to be physically swapped (instant recharge for a car). 3) Redundancy, if one battery breaks, the system can keep working, with reduced capacity, until a replacement is bought. 4) With the right control system it should be possible to transfer energy between batteries as required, allowing the car to be charged in-situ from the house, or the house to take energy from the car, if needed. The car can even be used to transfer energy from an external source into the domestic setting, the electrical equivalent of an oil tanker. 5) More efficient use of available capacity, by combining all batteries into a single system, they will be used more often, rather than sitting unused while people sleep or drive.