Installation and Operation Manual (Rev E)
SGI Series Inverters
DOCR-060371
19
4.3
DC Subcombiner Wiring
WARNING:
Before terminating AC or DC conductors at the inverter, ensure that the
conductors are deenergized by turning any AC and DC disconnects off, building AC
source circuits or breakers off and disconnect the PV module strings (or ensure that
the modules are covered).
WARNING:
Before connecting the DC conductors of the PV array to the subcombiner,
verify the polarity of the conductors.
WARNING:
Before connecting the DC conductors of the PV array to the subcombiner,
verify that the DC voltage is less than 600V DC. The PV array open circuit voltage must
be below 600V DC (V
pv
< 600V DC) under all conditions per NEC 690. Please read the
Technical Info section for details. Any DC voltage over 625V will damage the inverter
and void the warranty.
WARNING:
Fuses in the inverter’s ungrounded, fused subcombiner must only be
replaced with the same type and rating (600VDC) fuses as originally installed.
The SGI series of inverters must be ordered with either an integral subcombiner populated with
DC fuses
or
an integral subcombiner populated with DC breakers. Many choices are available to
meet any design constraint.
For the 225-400A fused or breaker subcombiner, choose any combination of current ratings
from 225A, 250A, 300A, 350A or 400A.
For the 110-200A fused or breaker subcombiner, choose any combination of current ratings
from 110A, 125A, 150A, 175A or 200A.
For the 70-100A fused subcombiner (no breaker option in this class), choose any combination
of fuse values from 70A, 80A, 90A or 100A.
Either copper or aluminum wire may be used for the DC (PV) positive and negative conductors,
although due to terminal size restrictions, aluminum wire may not be an option for all cases. As
with any aluminum wire exercise best industry practices to ensure a reliable connection;
thoroughly clean the conductor just prior to making the electrical connection and use an oxide
inhibitor to prevent the formation of aluminum oxide.
