It was 1812; they'd barely discovered how to generate electricity. But note that they describe effects like a persistent dry fog dimming sunlight over NA. That would have an effect on solar production and that was half a world away from the eruption.
> The idea of a global darkness for a significant period of time, would be extinction level.
Your scenario not mine; and I don't know why it needs to be global. I'm talking a 12-month period with much less sunshine than normal. A scenario which other sources of power would be independent of but that solar would be very correlated with. Since the nuclear disasters we've seen so far can be escaped by walking away from them slowly, that sort of rare volcanic event influencing solar production would probably be more damaging than a nuclear plant meltdown. It could kill a lot of people.
It is similar to Fukushima where the fact that they had an unsafe nuclear plant that maybe roughly doubled the damage caused by the tsunami that hit Japan. Heavy solar use might do something similar with big volcanic eruptions. We don't really know because we've never tried mass solar use before so it is a bit hard to judge how bad catastrophic failures are vs. nuclear.