Very likely all is well and you needed more absorb time or sun hours. Absolutely see if you can stack your modules for voltage, but it may be fine. My understanding is the controller would operate in PWM mode when lower ratio driven.
If your pv home runs are paralelled in the shack or cabinet, they are providing low loss transmission. If they are combined at the modules, they are suffering 4% loss but
should work.
The specs you gave look like maybe combined in the shack, but i dont know for sure.
Either way if you can, and as David was getting on to, id 'drive miss daisy' (controller) to 80-85% or so on all limits unless shoe-horning! Beware of cold.