The conduit between sub-
arrays and to the DC combiner box
should be designed to take the
shortest path possible. Run DC
wiring in metallic conduit when it
is located within a building. This
limits the risk of cutting live cir-
cuits when installing the ventila-
tion or any reconstruction on the
building. Consider using metal
conduit on the roof and wherever
the conduit is in direct sunlight for
reduced long-term maintenance in
extreme climates. This provides
longevity and wire protection.
Non-habitable Building
Requirements
PV arrays can be used on a variety of structures. Non-habitable buildings, such
as parking structures, are great for PV power system installation. However, they
must offer suitable solar exposure. Each building is already grounded. The elec-
trical isolation needed for PV panels and their components is already provided.
Ground-Mounted PV Arrays
Ground-mounted outdoor PV array installations can be set up in a variety of
ways. The most important factor in installing modules is the PV module
The location of the DC conductor is important. It
should also be protected from the environment.
Courtesy of PerfectPower, Inc.
CODE
NEC 2011, 690.4 (4)
Where the conductors of more than one PV system (sub-array or inverter) occupy the same junc-
tion box or raceway with removable cover(s), the AC and DC conductors of each system shall
be grouped separately by wire ties or similar means at least once, and then shall be grouped at
intervals not to exceed six feet.
Reprinted with permission from NFPA 70
®
, National Electrical Code
®
, Copyright© 2010, National Fire
Protection Association, Quincy, MA.
38 ADVANCED PHOTOVOLTAIC INSTALLATIONS
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