For an existing parallel setup, when it comes to updating the firmware do you have to disconnect the AC Out between the two devices before starting the update? I ask because I know the units are supposed to be factory reset after the update which I believe would unparallel the 2 units (I could be wrong on this) and I dont want to cause damage if the outputs are still wired in parallel but the configs for each unit are no longer set to parallel after they reboot.
The units will not be unparalled via updates. Only the VE-Configure configuration is resetted. After the updates (via VRM) the old configuration will be provided to download to your computer. If you open it via VE-Configure you will notice a short “converting” on top of the window. After that you can upload that old converted configuration to your installation and it will run without any changes.
Never the less i would disconnnect ac-in as the charger might start to charge the batteries with full power without configuration. AC-OUT should be fine.