User Guide

For AC coupled systems with Conext XW+/SW inverters, ensure the Li-ion battery packs
are sized so that the continuous rated charge power of the battery is equal to or greater than
the maximum power available from the AC Coupled PV inverter. Refer to the Battery
Inverter/PV Inverter Sizing section for more details on the sizing requirements.
When the maximum charge voltage is exceeded, the battery-based inverter will start
ramping up frequency and the PV inverter will curtail accordingly, however, the overall
control response time may not be fast enough to prevent exposure to a transient charge
power in certain conditions. For example, a sudden drop in loads or a transfer to backup
power operation when there are no loads present can cause the batteries to be exposed to a
short duration charge power up to the PV inverter power rating.
Due to the sensitivity of Li-ion batteries, it is highly recommended to include an over-voltage
protection relay to disconnect the AC coupled PV inverter in the event that the voltage
reaches or exceeds the battery's maximum operating voltage. The disconnect relay should
be installed at the critical load panel or other appropriate location, and connected in series
with the output of the PV inverters. The relay can be triggered by the 12 Volt Aux port of the
Conext XW+, set up to trigger on high battery cutout (HBCO). Select a relay with a coil drive
specification that does not exceed 80% of the 250mA XW Aux output rating. HBCO needs
to be set to an acceptable level, not exceeding the safe operating voltage of the Li-ion
battery (see the manufacturer’s specifications). Example relays include the SquareD™ 30A
power relay (PN:8501CDO16V51), and the Automation Direct™ 40A power relay (PN:AD-
PR40-2C-12D). With Li-ion batteries, it is also recommended to set the charge voltage
setting of the battery-based inverter to 98% of the manufacturer's specified charge voltage.
Refer to the Owner's Guide of the battery-based inverter for more information on these
settings.
AC Coupling in Generator-Based Systems
NOTICE
RISK OF DAMAGE TO THE GENERATOR
Never connect a generator to the AC Input terminal of a battery inverter configured for AC
coupling. The inverter will not be able to regulate the current being backfed into the AC input
and may backfeed AC current into the generator.
Failure to follow these instructions can result in equipment damage.
NOTICE
RISK OF DAMAGE TO THE INVERTER
Always check the recommendations of your equipment manufacturer when designing systems
with PVinverters that are AC-Coupled with a generator. Some PV inverters are susceptible to
failure when AC-Coupled with a generator.
Failure to follow these instructions can result in equipment damage.
In systems consisting of a generator as the secondary source of AC power, it is undesirable
to allow the PV inverter to come online when the generator is forming the grid (that is, the
battery inverter is in bypass mode and/or charging from a generator). In conditions where PV
976-0240-01-01 Revision G This document is intended for use by qualified personnel 9
Conext XW+/SW Battery Inverters and PV Solutions Guide