I am a newb although I do presently have a system working (2KW with AGM batteries). I want to add some prebuilt LifePO4 to my 24V system. I am having a hard time deciding between two 12v 200AH batteries or two 24V 100 AH. The 12V batteries would provide more "flexibility" in that it could charge them or use them on a 12V inverter separately in an emergency. OTOH, after a lot of confusing study I am given to wonder if putting these batteries in series poses some kind of challenge to keeping cells balanced or perhaps other issues.