All of this is misinformation and a non-issue. As said before the systems disconnect from the grid if the grid has no power. This is a technical system that needs to exist since the output power needs to be in-phase with the grid. No frequency to go by = no power.
Batteries are a different thing, and they work differently, but solar panels have no such thing.

Edit: just read up. When the grid disconnects the battery disconnects everything from grid and generates its own voltage and frequency for the system in your house (including solar panels)