Installation Guide

Installation
30 900-0168-01-00 Rev C
Multiple-Inverter AC Installations (Stacking)
Installing multiple inverters in a single AC system allows larger loads than a single inverter can handle.
This requires stacking. Stacking inverters refers to how they are wired within the system and then
programmed to coordinate activity. Stacking allows all units to work together as a single system.
Examples of stacking configurations include “parallel” and “three-phase” configurations.
Figure 22 OutBack HUB10.3 and MATE3
Each inverter must be assigned a stacking mode, “master” or “slave”, depending on the configuration.

The master provides the primary output phase. Other inverters in the system base their phase on that of the
master. 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 a parallel-stacked system, the master tends to be the most heavily used unit.
“Subphase master” inverters are used in three-phase systems. A subphase master inverter operates
semi-independently of the master inverter. Although the master inverter sets the phase relationship, the
subphase master creates an output independent of the master.
The master on the A phase output cannot measure loads and voltages on any other output. Subphase
masters are required to perform monitoring and regulation on the B and C phase outputs.

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.
~ The Power Save function can place slave inverters in “Silent” mode when not in use. They are activated
by the master or subphase master when required.
Each inverter is assigned to a particular phase when assigned a port on the HUB10.3 communications
manager. Port assignments will vary with the system. The master must be plugged into port 1. In
parallel stacking, any slave inverter can use any other port, beginning with port 2. In three-phase
stacking, the port assignments are very specific. See the HUB10.3 literature for more information.
Regardless, it is important to keep track of units and ports for programming purposes.
Programming uses the system display to assign a status and stacking value to the inverter on each
port. As long as the master is plugged into port 1, these assignments can be changed as needed.
HUB10.3
Additional Ports
P
o
r
t
1
MATE3 Port
MATE3
Stacking Connections
Stacking requires an OutBack HUB10.3 communications manager and a system display.
All interconnections between the products are made using CAT5 non-crossover cable.