Unfortunately that will still require 60+ relays for quite some currents (up to 160A for certain connections).That will also need a lot of space, and ...

You did get me to think about rotary switches, and I could turn them with stepmotors, but then the problem would be that during turning to the correct...

@ruplicator That would not make it computer controlled, which is a requirement. Also, I would like to use this system for a solar / powerwall system...

Recently I have found that in cases that MOSFETs are put back-to-back as in the series option, it is usual to put schottky's in parallel with the MOSF...