However, without a grid feed to synchronize to, your grid-tied inverters will be useless. You'd need battery backup and a second set of DC inverters to accomplish the off-grid scenario you're referring to.
That depends on the inverters. Plenty of inverters can operate in 'island mode' for off-grid applications.
You will have to have a lock-out installed that needs to be engaged before island mode will work if you are normally grid-tied. To avoid you hurting people or trying to power the nation in case of a black-out.
You will have to have a lock-out installed that needs to be engaged before island mode will work if you are normally grid-tied. To avoid you hurting people or trying to power the nation in case of a black-out.