Q: Can we AC-couple with Enphase microinverters?
A: Yes, you can use Enphase microinverters in an AC coupled system. A means of disconnecting the AC circuit from the array is needed to prevent battery overcharge during a utility outage. That can be done with a relay triggered by the AUX on the inverter on high battery voltage. Another way is for the battery inverter to change its output frequency to bump the microinverters off line on AC error (a relay should be used as a backup to this method). This is only needed when the system is in backup mode during a utility outage. This type of system should not be installed for a system used off grid for longer periods of time, as it does not adequately put a full charge on the battery bank.