DC charging limit / configuration?

I have 2× FranklinWH aPower (original), single aGate, ~27.2 kWh total. Solar is 6.96 kWp Enphase microinverter, AC-coupled, non-export.

When I’ve used Emergency Backup mode I’ve seen charge rates to the batteries close to 16 kW. But with solar charging I’ve never seen more than ~5 kW even on days when the array is producing well above that. Each original aPower has a 5 kW inverter, so I’d expect ~10 kW combined — but I’m seeing roughly half that from solar.

Is there an aGate configuration or setting that limits solar charge rate separately from grid charge rate? Or are both units supposed to participate in solar charging simultaneously?