Installation
Multiple-Inverter Installations (Stacking)
Installing multiple inverters in a single AC system allows larger loads than a single inverter can handle. This requires stacking. Stacking inverters does not refer to physically placing one on top of another. It 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
Stacking Connections
Stacking requires an OutBack HUB product, as well as a system display such as the OutBack MATE. A system using four or fewer units may use the HUB4. Systems using up to ten units require the HUB10. All interconnections are made using CAT5
HUB4 | MATE |
Additional Ports | Port 1 MATE Port |
Figure 19 OutBack HUB4 and MATE
Each inverter must be assigned a status — “master” or “slave”. The master is the primary and most heavily used unit. The master inverter’s MATE/HUB port must connect to port 1 on the HUB.
Slave inverters provide assistance when the loads are more than the master can handle alone. Slaves plug into ports 2 and above on the HUB. In general, it does not matter which slave connects to which port. However, 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. Each inverter is assigned to power an individual phase of the system. These assignments can be changed at any time as long as the master is plugged into port 1.
IMPORTANT:
The master inverter must always be connected to port 1 on the HUB. Connecting it elsewhere, or connecting a slave to port 1, will result in backfeed or output voltage errors which will shut the system down immediately.
Installing multiple inverters without stacking them (or stacking them improperly) will result in similar errors and shutdown.
Although stacking allows greater capacity, the loads, wiring, and breakers must still be sized appropriately. Overloading may cause breakers to trip or the inverters to shut down.
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