Hi guys.

I struggle to understand my own installation. It's been done in 3 phases.

First phase : 
1 x Axpert 5 kVa
12 x 270 W PV
4 in series x 2 in parallel = 1 bank of 12 V 200 Ah batteries :
1 x BVM-712

Second phase, upgrade to :
2 x Axpert 5 kVa

Third phase upgrade to : 
24 x 270 W PV
4 in series x 2 in parallel x 2 banks of 12 V 200 Ah batteries 
2 x BVM-712

At the moment, this is the way everything seemed to be plugged together (and I'm no expert at all, hence the struggle) : 

- 4 in series x 2 in parallel = 1 bank of 12 V 200 Ah batteries is plugged to one of the Axpert
- 4 in series x 2 in parallel = 1 bank of 12 V 200 Ah batteries is plugged to the other Axpert
- the 2 banks are linked to 1 shunt and 1 BVM-712 only, itself linked to one of the Axpert inverter

Does that seems right to you? The 2 batteries banks use a same type of battery but not the same brand. There not in the physical same space for a lack of space where the first bank was.
 

Interesting post and really interesting setup. Other professionals can help me out here, but  I was under the impression that even if you have multiple inverters they should all be connected to the same battery bank, not separate ones.

As to the connections of the batteries there is somewhere some very interesting research done about best way to connect 4 batteries and 8 batteries etc. So long story short connect batteries in first in parallel and then in series. Not sure if that is clear enough. But for eight 12 V batteries on a 48 V system you first create 4 blocks of two batteries in paralle and then connect all those in series. Somewhere I actually saw some detailed research but cant find the link now