It is illegal to sell electricity directly to someone else. To sell electricity you need to be licensed as an energy supplier.
So currently it is illegal to, for instance, sell your excess wind or solar electricity to your neighbour. You have to sell it to the grid and it goes into the "common pool".
With battery storage is it feasible to isolate/disconnect, move and then reconnect at another location, or once certified and turned on is it considered part of a system that can't be divided. It would be adding a significant cost to enable 'movement' of energy if you didn't need storage before and would need to be charged ahead of time, but it seems similar to fuel where I could give gas to a neighbor. I wouldn't expect that kind of scenario to work for the vast majority of people, but on a remote island it could be the kind of solution that gets engineered to keep homes working when an official solution takes a long time to arrive.
There are plug-in batteries these days. Charge it in one home, then chuck an extension cord over the fence to discharge to another home (ignoring safety concerns...)
So currently it is illegal to, for instance, sell your excess wind or solar electricity to your neighbour. You have to sell it to the grid and it goes into the "common pool".