If the system is configured correctly, you should barely touch Eskom, so you'd keep the system running on inverter,solar and batteries. It would only really need to dip into Eskom when you've hit the prepared oh kak point on the system

. I've got mine at 20%, so only once the batteries hit that it will switch to Eskom till it reaches 70%.
I mean switching it off isn't hard, just flick the cut over to Eskom, turn the switch to turn the panels off and then turn off the inverter. But I don't see why you'd want to?