Installation Guide

Installation
40 900-0160-01-01 Rev B
Multiple-Inverter AC Installations (Stacking)
Installing multiple inverters in a single AC system supports larger loads than a single inverter can
handle. This requires “stacking”. Stacking refers to how the inverters are wired within the system
and then programmed to coordinate activity. Stacking allows all units to work together as a
single system. The GS4048A and GS8048A models can stack up to ten units in parallel.
Figure 28 OutBack Communications Manager and System Display
Each inverter must be assigned a stacking mode, “master” or “slave” of some type depending on
the configuration.

The master inverter provides the primary output phase. Other inverters in the system base their phase on
that of the master inverter. If the master shuts off, all other inverters also shut off. The master must
sense and connect to an AC source before other inverters can connect.
~ In all cases, the master inverter must be connected to port 1 on the communications manager.
~ In a parallel-stacked system, the master tends to be the most heavily used unit.

A slave inverter does not create an independent output. It simply assists the master or subphase master
by adding power to the output as needed.
~ Only one slave mode, “OutBack”, is available for the GS8048A and GS4048A. This mode is used for
inverters stacked in parallel.
~ All slave inverters are in phase with the master. The slave outputs are pulse-width-matched to be
precisely synchronized with the master inverter. This avoids potential backfeed.
~ OutBack slaves can be placed in Power Save mode when not in use. They are activated by the
master inverter as needed. For this reason, the master is normally the only inverter to enter
Search mode.
Connect all inverters other than the master to communications manager ports 2 and above.
The system display may have other port restrictions pertaining to stacking. In general, it is always
important to keep track of units and ports for programming purposes.
MATE3s
System Display
Additional Ports
Port 1
MATE
Port
HUB10.3
Communications
Manager
Stacking Connections
Stacking requires an OutBack communications manager and a system display.

A system of four or fewer units may use the HUB4 Communications Manager.

A system of up to ten units requires the HUB10.3 Communications Manager.

All interconnections between the products are made using CAT5 non-crossover cable.