You are missing the disconnect relay in the AC1 line. There a 4 + 1 relays: one for each leg in the AC1 (grid) line, one for each leg in the AC2 (gen) line and a NFT neutral disconnect relay on the AC (out) N line for preventing imbalance current via the toroidal transformer when grid connected.
AC(out) is always connected to the output of the toroidal transformer and always powered by the inverter. The AC1 lines are not powered and they are disconnected because the AC1 sensing transformers do not detect a grid voltage. When you use AC1 for the AC coupled micro-grid connect it will work because the sensing transformers detect the Enphase reference voltage and the XW Pro connects the relay in the AC1 line after phase sync as in a normal grid operation. Using the AC1 has advantages because in an EPO scenario you can tie in the XW Pro into the Enphase EPO and all DER resources will disconnect. If you stay on the AC(out) line, then the backup panel will be energized in an EPO scenario. You can try this, switch the Enphase off and check the power supplied by the XW Pro.
You are always limited to 28A per XW Pro on the inverter output, except for the surge to 56 A. You can stack 2 or more if you need more power.
There is more to this regarding who provides the micro-grid reference voltage, depending how the subcomponents are switched on. Either the XW Pro if switched on first and Enphase follows, or the Enphase IQ controller if switched on first and the XW Pro follows. Assuming you want to connect the grid to the IQ system controller, the 2nd case is better.
AC(out) is always connected to the output of the toroidal transformer and always powered by the inverter. The AC1 lines are not powered and they are disconnected because the AC1 sensing transformers do not detect a grid voltage. When you use AC1 for the AC coupled micro-grid connect it will work because the sensing transformers detect the Enphase reference voltage and the XW Pro connects the relay in the AC1 line after phase sync as in a normal grid operation. Using the AC1 has advantages because in an EPO scenario you can tie in the XW Pro into the Enphase EPO and all DER resources will disconnect. If you stay on the AC(out) line, then the backup panel will be energized in an EPO scenario. You can try this, switch the Enphase off and check the power supplied by the XW Pro.
You are always limited to 28A per XW Pro on the inverter output, except for the surge to 56 A. You can stack 2 or more if you need more power.
There is more to this regarding who provides the micro-grid reference voltage, depending how the subcomponents are switched on. Either the XW Pro if switched on first and Enphase follows, or the Enphase IQ controller if switched on first and the XW Pro follows. Assuming you want to connect the grid to the IQ system controller, the 2nd case is better.