I wonder how many home/commercial/community solar systems (battery-backed or not) have the equipment needed to (a) generate their own 60 Hz sine wave (of good-enough quality to sync to the grid), (b) automatically disconnect from the grid when it loses its connection (to prevent backfeeding during outages), and (c) properly reconnect (including syncing) when the grid comes back.

I remember, at least in the beginning, smaller systems were unable to provide their own sine wave, and would rely on the grid for that. And even today, if full net-metering were in place (with the possibility of export), I would expect the grid to still provide phase synchronization (when solar is not exporting), and a path to other consumers (when solar is exporting).