Apologies - you're right, I've stated it badly. But then it uses the grid for the full load, it is a full switch over to grid. Some versions can combine, such as the King, but if you exceed the rated capacity it will also fully switch to the grid. Basically the inverter output of the Axpert is limited to what it can invert from DC. With the Victron the output is a sum of what it can invert from DC and what it can take from the grid.

So in my house I run everything of the Victron (4 kW, 5 kVA), including geyser (2 kW element). If the geyser is on, and I switch the oven on (3 kW), my total load is 5 kW. It will use sun and battery to provide 4 kW of that, and it will take the remaining 1 kW from the grid.

Whereas with the Axpert, if the inverter can do 4 kW, and your load is 5 kW, it will fully switch back to the grid. With models like the King, if you have 2 kW available from sun or batteries, and your load is 4 kW, it will take 2 kW from sun/batteries and combine with 2 kW from the grid to give you your 4 kW. But increase the load to 5 kW, and it will take all 5 kW from the grid.