Operation
28
900-0198-01-00 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 be sized to the wattage of multiple inverters. They can be powered by all
the inverters on that output. They can also be assisted by the other 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.
Figure 11
Example of Series/Parallel Stacking Arrangement (Four Inverters)
Three-Phase Stacking
In three-phase stacking, inverters create three separate 120 Vac output phases in a wye configuration.
The output of each inverter is 120° out of phase from the others. Any two outputs produce 208 Vac between
them. The outputs can be used to power three-phase loads when all inverters work together.
The 120 Vac loads on each output cannot exceed a given inverter’s wattage. The other outputs cannot assist.
Only three inverters, one per phase, may be installed in a three-phase arrangement.
Figure 12
Example of Three-Phase Stacking Arrangement (Three Inverters)
LOAD
OB Slave L1
OB Slave
3.0 kVA 120 Vac
3.0 kVA 120 Vac
3.0 kVA 120 Vac
3.0 kVA 120 Vac
12.0 kVA
240 Vac
6+ kVA
120 Vac
6+ kVA
120 Vac
OR
1-2phase
OB Slave L2
FW-X240
2.0 kVA 120 Vac
2.0 kVA 120 Vac
2.0 kVA 120 Vac
2.0 kVA
120 Vac
6.0 kVA
208 Vac
2.0 kVA
120 Vac
2.0 kVA
120 Vac
LOAD
OR
C Phase Master
B Phase Master
Master
