We have just installed an 8kvA Multiplus 2 with a Smartsolar 450/100 MPPT and 3 off 6.4kWh BSL Batteries. Two strings of panels. (8 by 550w and 6 by 550w). The maximum charge power from the MPPT seems to be limiting to 3kva. With either string switched off, the connected one produces about 3kva alone and when working together, they drop to around 1.5kva each. This is a charge current of around 50A and the max charge current is set to 95A. What else could be limiting the charge power?
