Wigwam not every BEV will be connected to the grid at all times similarly they all won’t be disconnected at the same time.The fact is there will be no need for all BEVs to be connected at the same time, the answer, as always, is somewhere in between.
Maybe what you don’t know is that those choosing to share the energy stored in their BEV will get paid, up to £200ish per year for doing so.
There’s nothing like a bit of free cash to persuade people to join in.