This article was written in 2012 by Boston U. geophysicist Robert M. Schoch. It’s no less true in any way today (although power companies are somewhat better prepared thanks to articles like this one - and they were nervous last week).
Auroras would be much easier to see if it this happened and the lights went out for months. Website:www.robertschoch.com
Regarding transformers: it’s easier to let a power grid trip offline (and transformers are designed to behave so instead of being overpowered) rather than to keep operating despite a Carrington level solar storm and suffer failure on all longer east-west connections.
Also, I don’t think they used capacitors to protect their high voltage lines back in 1921, because the article Overvoltage Protection of Series Capacitor Banks notes:
Also, failure on north-south connections isn’t nearly as likely, so a considerable part of the transformer “population” would be spared from impact.
Thus, while a single strong solar storm within the limit charted out in 1859 would be an extreme inconvenience and strong economic setback, it seems unlikely to end civilization.
A long period of severe solar storms could also result in ozone depletion in the atmosphere and become another extreme inconvenience - through increased UV exposure. However, most forms of life have seen such things in their evolutionary past, and humans have the ability to wear glasses, clothes and apply sun screen.
They don’t talk about it a lot, but. If it looks really bad, I suspect that what the grid operators will do is disconnect and shut down as much of it as possible and wait it out. Better to have no electricity for a week than for hundreds of transformers to be ruined …