Binky if it did happen, all electronic systems barring maybe some designed to be immune would fuse, whether they were switched on or not, the theoretical nature of EMP, which would surely accompany a solar flare of radiation from the sun, is a burst of energy which momentarily generates massive currents in all electrical circuits.

I think we should be assured to know that such an event would even fuse the electrical circuits in our own heads, so we would probably all be dead, like our electronic devices.

Worrying about this is like worrying about being struck with lightning, it seems to me; not worth worrying about at all :)