At an extremely abstract level, it is conceptually simple, but most inverters are designed with safeguards to prevent exactly this. They only produce power when

At an extremely abstract level, it is conceptually simple, but most inverters are designed with safeguards to prevent exactly this. They only produce power when the grid is up, and in phase with it. Because if not sequenced and interlocked, islanding behavior can result in back-powering parts of the grid that are supposed to be disconnected and down for maintenance, or creation of desynchronized islands that then cause more damage when reconnected. This is absolutely a problem that operators need to solve. Radio synchronization is possible, neighborhood islanding could be beneficial, etc. There are entire village-wide micro-grids in remote places where everyone's inverters do perform these functions, it just hasn't been embraced in monopoly environments yet. For instance, relays that close isolated parts back onto the main network would need to be phase-aware, to only reconnect if it's safe to do so. You could mandate that all island-mode inverters center themselves around 50.1 or 60.1Hz in the absence of outside influence so there's certain to be phasing opportunities. Distribution networks would need more switches to provide positive isolation during maintenance. And all of these things would need huge amounts of interoperability testing. It's possible, but it has a cost.