If we had a large one like the Carrington Event in 1859, the biggest problems would be things like power lines would be shorted out as they act like long wire antennas for the energy, iirc back then it blew out the telegraph system and melted train tracks as they are like long antennas.

It is not like a nuclear EMP where it frys the small electronics in cars and computers.

But could induce high voltage, high amps into your home power circuits but there are things to mitigate this similar to lighting protectors.

We have ways of detecting the solar flare so there is a chance you will be told ahead of time and can do something like unplug everything and i would guess the power companies must have some way of disconnecting the grid from the long power lines to help reduce the damage.

The biggest problem would be after the power grid is down it will take months and months if not years to fix it all as most of the big transformers have a 6month lead time and with everyone wanting them i could see some areas without power for a long time.

Its been a while since i read up on the effect of huge solar flares but that is what i remember, best thing you can do is prep with generators and some solar panels and maybe plan to go back to living like its the 1700's or like the amish :)