In Off-Grid situation (no AC-In), can we use ESS programmable relay to activate AC-Out2 according to the state of charge of the battery pour feed AC-Loads from the battery?
The AC 2out is programmed with a different assistant caled the programmable relay assistant.
ESS assistant is used for grid connected systea to prioritise battery and solar over grid (both happen automatically when you are offgrid 
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There is not much in the documentation, but you can open ve configure in demo mode and play with the wizard before you try it on the live system