[londons_explore]

There is typically good connectivity between houses. That means even if your EV isn't home, the other EV's in your street can send your house a lot of energy.

Unfortunately anti-islanding rules from power companies generally disallow you using the power lines between your house and a neighbours while the grid connection is disconnected elsewhere.

These rules could be adjusted though - although it would take a lot of systems design work to ensure power system stability and re-synchronizability even with every possible combination of islands.

[pjc50]

It's more about safety than reconnection: when repairing lines, it's much more manageable to "lock and tag out" the upstream side than all the distributed generation, especially in emergencies.

[londons_explore]

Any lines being worked on will be shorted (ie. all conductors joined together and to ground).

As long as that is always done, islanding doesn't present any human safety concerns.

That is normally done anyway, because plenty of utility breakers will automatically try to reconnect every few minutes (allowing some grid scale failures to repair themselves with no human involvement).