If a few individuals did it, no. Plugging in a 200 watt source would be equivalent to unplugging a 200 watt load. That's the equivalent of turning off 4 incandescent light bulbs. I think I might have seen the power grid handle that kind of "disruption."

On the other hand, imagine if 100 million people go out and buy 100 watt solar panel kits. The load on the power grid is going to vary by a gigawatt every sunrise and sunset. A city in which a million people have 100 watt panels will have to handle a variance of 100 megawatts every time a cloud rolls over town.

At the individual level, what concerns me about the "panel you plug into a normal outlet" form factor is that it breaks a bunch of fundamental principles of the power grid, like "sources of power should be sockets not plugs, so that it's at least nominally difficult to touch live wires." Having a source of power on the load side of a circuit breaker further rustles my jimmies. I think the only thing that's going to stop them from causing problems like overheating wires in walls is the practical limit on panel size.

If you're going to plug solar panels into the grid this way, they're going to have to be well engineered or they're going to hurt someone. You don't want to own one of these if Big Clive has a lot to say about them, and since most of them are going to be manufactured in China...just expect an increase in residential fires as more jurisdictions approve them for use.

I the case of an outage you aren't totally screwed and there is currently no protection of power generator stations globally against missile attack. No interceptors. Russia looks like its going to go on the offensive. The more people that do this the few people your government is going to have to triage since you will be able to make do.

Maybe. During a good sunshine you will probably generating more power than you use, and so leak power back into the grid. Can be detected.

Here, in Germany, the power net companies claim they'll look at the roofs when they're out and about and check if you have more than 2 kWp (probably just more than 4 panels) without registering properly. Up to 2kWp mostly no one cares.