Outback Power Systems GS4048A Installation Manual - Manual (Page 35)

Installation
900-0160-01-00 Rev A 33
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”, 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 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.
 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 units other than the master to ports 2 and above on the communications manager.
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.
Programming involves using the system display to assign a status and stacking value to the inverter
on each port. The stacking assignments can be changed at any time as long as the master is
connected to port 1.
Port 1 Additional Ports MATE3 Port
MATE3 HUB4
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 either the HUB10 or HUB10.3 Communications Manager.
 All interconnections between the products are made using CAT5 non-crossover cable.