Jorrit OK, so the the issue with the TLX inverter looks like it does not seem to have percentage SOC targets or stop percentage available against the timeslots, like it has on some of the SPH hybrid inverters.
So best option might be to just cut your end time for the window short, based on a start/trigger SOC as specified in WW and the discharge rate of your inverter.
What setting do you configure and where in the Growatt portal is that? Can you put a screengrab in here for context please?