Installation Manual

Installation
36 900-0197-01-00 Rev A
Series/Parallel Stacking (Quad-Stack or Larger)
In series/parallel stacking, inverters use OutBack series stacking create separate 120 Vac output phases
and 240 Vac collectively. However, in this configuration, each output has parallel inverters. One output
contains the master; the other uses a slave. Each output has at least one additional slave.

The 120 Vac loads on each output can exceed the size of a single inverter. They can be powered by all the
inverters on that output.

The slave outputs cannot operate independently. The slaves can go into Power Save mode when not in use.

Up to ten inverters may be installed in a series/parallel arrangement. All inverters must be the same model.
Figure 28 Example of Series/Parallel Stacking Arrangement (Four Inverters)
When installing a multiple-inverter series/parallel system, observe the following rules.

Series/parallel stacking requires one or more FW-X240 autotransformers, a system display and a communications
manager. Port assignments and jumper positions vary with model and stacking configuration.

A system of four mobile FX or VFX inverters can use a single FX-X240 balancing transformer. If more than four
inverters are used, the output must be balanced with additional transformers. Two transformers are required for
series/parallel systems of up to eight inverters. For a ten-inverter system, three transformers are required.

The inverter that is mounted physically lowest is always the master. It is the primary L1 output. Mounting the
master below the other inverters allows the master to avoid heat buildup and remain relatively cool.

The master must be connected to communications manager port 1. It is programmed as
1-2phase Master
.
Other inverters must not be selected as master.

All other inverters on the L1output, regardless of number, must be programmed as
OB Slave L1
during
programming.

All inverters on the L2 output, regardless of number, must be programmed as
OB Slave L2
during programming.
See the HUB Communications Manager literature for port assignments.

All overcurrent devices must be sized for 30 Aac or less. All wiring must be sized for 60 Aac or more.

All output circuit breakers must be sized appropriately for loads and inverter power.

The AC input (generator or shore power) must be 120/240 Vac (split-phase).
LOAD PANEL
OB Slave L1
OB Slave L2
3 kVA 120 Vac
3 kVA 120 Vac
3 kVA 120 Vac
3 kVA 120 Vac
12 kVA
240 Vac
6 kVA
120 Vac
6 kVA
120 Vac
OR
1-2phase Master OB Slave L2
FW-X240