A few days ago I had this conversation with the main tech consultant at Real Goods in Hopland California, basically the original real deal Mecca of the off grid world. They have been running educational seminars for 20 years now.

Consensus is that batteries are definitely EMP proof. Panels could be damaged but repairable.

There was no mention of surge suppressors, but the concept makes sense.

There was mention of metal shielding on the cables, like running the cables in metal conduit.

Backup charge controllers, inverters and voltage testers stored in Faraday cages seems to be the best bet for long term preparation.