AC Coupling Guide

Prerequisites
It is recommended to upgrade to the latest XW Pro and Conext Gateway firmware before
configuring the equipment. Consult Conext Gateway Owner's Guide (975-0806-01-03)
and XW Pro Owner's Guide (document number 990-91227 or 990-91402) for firmware
upgrade instructions. To find the latest firmware, go to https://solar.schneider-
electric.com/products/inverterchargers/ > your product > Downloads > Firmware.
CAUTION
RISK OF INJURY AND EQUIPMENT DAMAGE
n To prevent battery damage in a micro-grid AC system, always use the latest firmware
available for your inverter.
n If Li-ion batteries are used, ensure they have an external battery management system
(BMS).
Failure to follow these instructions can result in injury or equipment damage.
Overview
When a PV inverter is connected to the AC output of a battery inverter, the system is
referred to as an AC-coupled system. In this configuration, the PV inverter is exposed to
the AC output voltage of the battery-based inverter, which is responsible for grid forming
during off-grid/backup operation. The PV inverter injects power to the critical load panel
and the AC output of the battery-based inverter. The inverters are thus “AC-coupled” with
each other and are able to share PV solar and/or battery energy to the loads.
Figure 1AC-Coupled System Diagram
An example of AC Coupling with the XW Pro is shown in Figure 1. The PV system is
connected to the grid through the internal relay located on the AC bus inside the XW Pro
inverter. This allows power to be produced and supplied or “sold” back to the grid if it
exceeds the power consumed by the critical loads. When the grid goes out of limits, the
XW Pro AC Coupling Solutions Guide Introduction
8 This manual is intended for use by qualified personnel 990-6421