I agree with several of the others. There is nothing you can do to protect it and still have it outside an in operation. You could choose to store it away in a faraday cage that you can construct yourself in the anticipation of an EMP or MCE. Just don’t ground it. EMPs and MCEs have a ground re-bound that can destroy grounded equipment.
I stumbled across a solar system company that advertised for additional cost they could EMP-proof a system you purchased from them, but I didn’t keep the link. Sorry.