Battery charge rate capped at 2.6kw

I have just had a 16.4kwh, two 8.2kwh Batteries, connected to a 5KW hybrid inverter and a 4.6kw PV system. I want to charge at night from Octopus EV go, 00:30-04:30. However the max charge rate seems to be capped at 2.6kw. So the batteries can’t charge fully overnight in 4 hours if we’ve had a poor day of solar generation. Currently only getting about 50% of the batteries charged over night.
The data sheets show a max charge rate of 85A for the batteries and a max charging current for the inverter of 50A.
Is there a setting that I need to adjust?

Collard33 not what you want to hear but thats your lot on the Gen 1 Hybrid.
51.2V x 50A = 2.6kW

No way around it other than upgrading to gen 2 to get 3.6kW.

Getting a 6 hour off-peak for less than the 5 hour Go Faster was one of the reasons why I moved to Intelligent Octopus. Much better chance of filling my 16.4kWh batteries.

Thanks both.