Zero. There are batteries that come in car shape and with wheels. People pay for them and there will be tens of millions, eventually 250m. They are mostly stati

Zero. There are batteries that come in car shape and with wheels. People pay for them and there will be tens of millions, eventually 250m. They are mostly stationery (23+ hours/day) and are used 20 mins - 1 hour/day. They form a gigantic distributed storage reservoir, can absorb excess power (and get paid for it! energy prices go negative!) and supply power back to the grid when needed (and get paid again!).