I appreciate your comments, but think that you don't fully grasp the the level of damage an NEMP can do to the semiconductors in a BMS, especially when they are connected to the lengthy, unshielded conductors found in almost all solar setups.
Tests that were run at Sandia in conjunction with the EMP Commission indicate that plain lead-acid batteries, with their negative terminals properly grounded, are unaffected by any foreseeable level of NEMP up to 50kv/meter unless connected to extremely long conductors (several hundreds of yards in length), or to the grid via a charger, and even then are quite resilient, with only minor damage occurring that didn't affect their capacity or further operation. As far as aI know, no LiPo4 batteries were tested, as this was some years ago before they were really on the scene; however, it's likely that the batteries themselves would be fairly resilient since they share a reasonably-similar architecture with other storage batteries, the major difference being their internal BMS and it's semiconductors that are extremely vulnerable to the E1 and E2 components of even a moderate NEMP event. If the internal and practically non-accessible BMS is destroyed, charging the battery becomes extremely problematic.
Everyone has to decide for themselves what risks they are willing to take with their alternative energy system; I've given my opinion here based on my years of real-world electronics experience, as well as the conclusions of the various NEMP study commissions over the past couple of decades and correspondence with their members, so I really have no more to say on the matter.
Wait, you fear an nuclear EMP attack. Let's pretend that that's a 100% probability. the battery systems would be the least of your worries. let's keep indulging in this though. BMS are generally designed and built in China except for some very expensive ones here in USA. they are cheap, you could carry spares. What did they say if the BMS is not connected though? can you have a spare(s) and just replace if needed? what I'm most confused about is that you are implying the BMS is NEEDED for you to charge the battery bank, it's not, it's just a protection device, it does prevent overcharging, overvoltage, overcurrent, etc. but in an emergency situation like you describe, remove the BMS and ASSUMING the solar charge controller still works than you just plug it up to the battery bank. in fact in emergencies , if you can verify what the solar panels are outputting or have a way to measure voltage with lets say an analog or other voltage meter you simply refer to the printed chart of lifep04 and stop at 100% state of charge (SOC). Dr. Jones I assure you there is always a way, never think because one way is closed that it becomes impossible. You are a doctor, you're smart as hell, just teach your mindset to be more mechanically inclined and find solutions. In solar there are many people that say something cannot be done, I assure you it's not the case usually.
They told me rebuilding a 5 speed automatic transmissions was a job ONLY for professionals, there's hundreds of parts in it that would be too daunting for many people. I proved them wrong when they said I was too stupid. not only did I disassemble every piece in the transaxle, I also found out the reason and found a solution on how to fix it. all honda transmissions and models around the 1999-2006 era had transmission problems, I found out why and how and made videos and articles explaining how to fix it. with no prior experience. I also did a few other things that are fairly hard. I mean you're a doctor, you know what I'm saying. Don't close the door because you or someone else thinks it's impossible, find a way, you can do it!