What have I forgotten in my settings?
Enphase installation (envoy not metered - IQ8+ inverters) standard connected to AC-in -> works perfect.
BUT
When I switch to off-grid (manual transfer switch) then the enphase comes to the ACout1 but the production stays at a several Watt's. On the envoy the power led stays red while there is 230V & 49.9-50.1 Hz (so no reason to switch off). Have seen several similar questions yet but not a answer how to solve this problem.