vinodh

There was an similar  post a few month ago worth looking it up .
I personally don't have an issue when power is down for a few days to  throwing an extension over the wall just for my neighbor to keep his fridges cold through the day saving him hundred or thousand in lost meat . 
I remember someone in an the similar post mentioning you not allowed to connect your houses power to neighbors house . So permanent sharing could be an issue 

I’m no electrical wizz but potentially one way this could work is if the complex has a communal battery, when you export the power goes into that battery then whomever needs power can draw from that when there is no grid. There are frequency and earth-neutral considerations as well