User Guide

generation exceeds AC load and battery charging consumption, excess PV power could
flow to the generator with potentially damaging effects.
While running a generator in an AC-Coupled system, the generator will provide AC power to
the battery-based inverter and the PV inverter. The PV inverter will detect this and begin to
inject energy to the system. Generators and other AC sources are not designed to accept
backfed power, so there must be a way to disallow the concurrent operation of the AC
source and PV inverters on the system. This can be done manually or through the use of
interlocked AC transfer contactors.
In all cases, while the generator is running, the PV inverter must be disconnected from the
circuit. PV harvest is only possible when the generator is not running and is disconnected,
and the Conext XW+/SW is inverting.
It is possible to use a disconnect switch to automatically disconnect the PV inverters when
the generator is operating. To do this, a pair of interlocked disconnect switches can be
installed. One is placed between the generator output and the AC input of the battery-based
inverter, and a second one between the PV inverter and critical load panel.
Note: The power metering on the Conext XW+ may not work as expected when it is in
voltage source invert mode and power is flowing back into the batteries.
Figure 3AC-Coupled System with Generator
XW+ Inverter/Charger
AC Critical Load
Panel
PV Inverters
Generator − AC Input 2
Grid − AC Input 1
Either/or
Interlocked
AC Switch
GT/TX Output
Main AC Panel
XW+ Inverter Output
Battery Charge Control Using Frequency Shift
The Conext XW+ regulates the battery charge using Frequency Shift. This technique
exploits the active power reduction versus frequency feature of PV Inverters (frequency-
Watt). This is a key feature of modern smart inverters, but may be absent in older legacy PV
inverters. See Lithium Ion (Li-ion) Battery Compatibility on page 8.
976-0240-01-01 Revision G This document is intended for use by qualified personnel 10
Conext XW+/SW Battery Inverters and PV Solutions Guide