The first thing that stood out for me was to make some of the battery cable lengths the same length even though it will not be the same distance covered.
The RED and BLACK cables from the controller to the battery bank should be the same longer lengths. I would make these cables 4AWG size.
The LIKE cables inside the battery bank path should be equal path lengths.
Cables inside the battery bank 4-8, 8-12, 1-5, 5-9 should be the same longer lengths. I would make these cables 2AWG size
Cables inside the battery bank 2-3, 6-7, 10-11 should be the same shorter lengths. I would make these cables 2AWG size.
All of the cables short and long do not have to be the same length just the LIKE paths should be equal lengths.
When done you will end up with three different battery cables group lengths being the two cables coming from the solar controller one length, Inside the battery bank you will have four longer group lengths and three shorter group lengths.
The idea is that all battery groups get fed by the same amount of current coming from the combined solar panels when being charged. Otherwise some batteries will not charge up to the same level and may affect the overall BATTERY OUTPUT when being used. Eventually will do some harm to certain battery groups...
I would make the cables feeding the 12VDC Distribution Panel where all of your fuses circuits are and frame ground connections at least 4AWG size. Some may want to see these at 2AWG size.
These 6VDC Batteries can produce some serious DC AMPS... The cabling outside the battery bank should be protected with in-line FUSES or auto circuit breakers.
Just my observations - I'm sure others will have different ideas...
Roy Ken
