Hi T. Passthrough mode will happen when your charger is disabled. Hopefully you have access to VEConfig3 to set it up.
In the Charger tab, make sure 'Enable Charger' box is ticked.
This supposedly also happens when 'AC Input Current Limit' is set to zero. Extrapolating from there, perhaps a zero setting on the Multi Control panel could do this too (can't confirm that).
Maybe there's other ways this could happen too, but I'm unaware..
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