This isn't the first time car batteries have been used for renewable power. Renault is reusing Zoe batteries on a 'smart island,' for example. It's Vattenfall's largest rollout to date, though, and it hints at what electrical grids may eventually look like in the UK and beyond: wind and solar sources backed up with batteries from car manufacturers.

This also illustrates how some automakers may thrive going forward. Large-scale battery deployments like this not only help them make the most of their EV production (they don't have to limit battery production to cars), it helps them reuse batteries when owners retire their vehicles.