IIRC there was some article linked to on hn some time ago where it was explained that most rooftop solar installations actually don't work at all without a grid. If the grid goes down, so does the solar. It's of course technically possible to fix, but costs more.

I think that is about to change in the near future.

https://pv-magazine-usa.com/2018/08/20/enphase-going-einstei...

https://enphase.com/en-us/ensemble

"As utilities fight distributed generation, electricity is getting less reliable"

https://pv-magazine-usa.com/2019/01/03/as-utilities-fight-di...