Hybrid inverters will not acquire sync from AC output port. Initial synchronization sensing is on AC input port, prior to pass-through relay closing.
You cannot use AC coupling to couple two independent hybrid inverters outputs. Both units will assume they are phase masters causing a clash between the two inverters.
On a hybrid inverter, when AC pass-through relay is closed, it follows the leader (AC input), when AC pass-through relay is open, it is its own phase master. (unless it has paralleling control link interface to assign control sync)
Inverter-generators do not have an AC input and use a different mechanism to sync two parallel inverter-generators. On inverter-generators, IF there is AC voltage present on its output when inverter-generator is started it will take its synchronization from the applied AC source to output port. You must start one inverter-generator first before starting the second. The second inverter-generator will continue to be a slave, maintaining sync with the first started unit.
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