Yes, if you turn off the power switch at the bottom of the inverter it will shut off the Inverter portion of the unit and the MPPT charge controller will still continue to function and charge the battery. I currently am having an issue with this. I have posted this in another thread. Search for...
"Growatt SPF 3000TL LVM-24P - Bypass Error Issue"
You can see the error I am getting just incase you have the same issue.