II wonder if it normally possible to set the size of the main fuse to the grid for solar inverters
I’m thinking of a system with pv panels, batteries and a centralinverter connected to pv-panels,battery, grind and consumers in the house.
As my grid connection is limited to 6.9 kVA I would like the inverter to maximize the power drawn from the grid to that value. And should the load from consumers be larger than that the rest of the energy be taken from the batteries (or all from the batteries and then them be charged from pv-panels and of course the grid if they are low enough.
You should not change the grid supply fuse size (circuit breaker). This will be fixed according the grid supply, cable size, etc.
However, I think what you are asking for is an inverter which can do what is called ‘peak lopping or peak-shaving’. This is when the inverter can supply any excess power over a preset value. Some of the more powerful interactive (multi-mode) inverters can do this such as Selectronic SP PRO and the Schneider XW series.