sum of the open-circuit voltage of the series-connected PV
modules for the lowest expected ambient temperature.
Refer to the National Electrical Code Article 690-7(A) for
determining the maximum number of the PV module that
can be placed
in series. Temperature coefficients, specific
to the module of use, can be used to provide the most
accurate prediction of module voltage under temperature
extremes.
NOTE: Limit the maximum number of series connection of
the PV module so that the system voltage is 600V or less.
NOTE: Do not connect the modules in parallel without
maximum over current protection.
NOTE: The minimum radius that the cable can be bent for
the PV module is 1.14” (29mm).
NOTE: Under normal conditions, PV modules may produce
more current and/or voltage than reported in the standard
test conditions. Therefore, when voltage evaluations for
components, capacity of conductors, size of fuses, and size
of control systems connected to the module output are
determined, multiply the values of short-circuit current (Isc)
and open-circuit voltage (Voc) that are marked in the PV
modules by the coefficient, 1.25.
NOTE:
Refer to Section 690-8 of the National Electrical
Code for an additional multiplying factor of 125 percent (80
percent derating) which may be applicable.
8. GROUNDING
Before installation, consult the local codes and the
authorities having jurisdiction to determine the necessary
grounding requirements. When installing in the US market,
attach all PV module frames to an earth ground in
accordance with the National Electrical Code (NEC) Article
250. Proper grounding is achieved by connecting PV
module frames and all metallic structural members
contiguously to one another using a suitable grounding
conductor. The grounding conductor shall be of copper,
copper alloy or another material suitable for use as an
electrical conductor per NEC. The grounding conductor
must then make a connection to earth using a suitable earth
grounding electrode. Ensure positive electrical contact
through the anodizing on the module frame extrusion by
utilizing one of the following methods.
Attach the grounding conductor:
(1) to one of the .28” (7mm) diameter holes marked
“ground” using 1/4”(6mm) stainless steel bolt. Wrap
conductor around bolt. Tighten the screws with
adequate torque (usually 62 in-lb; refer structure
manufacturer specifications).
(2) to a ground lug (manufacturer:ILSCO, model:GBL-
4DBT). The lug is attached to one of the .28”(7mm)
diameter holes marked “ground”, using #10-32
stainless steel bolt with 40 in-lb torque.
(3) to a ground lug (manufacturer:ILSCO, model:GBL-
4DBT). The lug is attached to one of the .16”(4mm)
diameter holes marked “ground”, using #10-32
stainless steel tapping machine screw with 30 in-lb
torque. Screw length should be 20mm or less.
(4)
to a wire bolt (manufacturer:Tyco, model:2058729-1)
using 3/8”(10mm) wire biding nut with 45 in-lb torque.
The bolt is attached to one of the .19”(4.7mm) diameter
holes marked “ground”, using #8-32 (4mm) mounting
washer nut with 25 in-lb torque.
NOTE: A stainless steel star washer or mounting washer
nut, having contact with anodized surface of the frame,
must be employed to break through the anodized layer of
the frame extrusion and electrically connect the grounding
conductor to the conducting aluminum frame material.
NOTE: As a general rule, avoid direct contact of copper or
copper alloy ground conductors with the aluminum frame
to prevent galvanic corrosion. All ground bond securing
hardware in contact with either the aluminum module
frame and/or copper or copper alloy ground conductors
must be stainless steel.
(1) (2)
(3) (4)
9. BLOCKING DIODES
In systems utilizing a battery, blocking diodes are typically
placed between the battery and PV module output to
prevent battery from discharging at night. The PV module is
made of polycrystalline cells with high electrical “back flow”
resistance to nighttime battery discharging. As a result, the
PV modules do not contain a blocking diode when shipped
from the factory. Most PV charge regulators and inverters
incorporate a nighttime disconnect feature.
10. BYPASS DIODES
Partial shading of an individual module in a source circuit
string (i.e. two or more modules connected in series) can
cause a reverse voltage across the shaded cells within the
module. Module output current is then forced through the
shaded area by the remaining illuminated cells and other
PV modules in series with the partially shaded module(s).
The current forced through the shaded cells within the PV
module(s) causes additional module heating and severe
loss of power. All the PV modules are supplied with factory
Nut
Spring washer
Flat washer
Star washer
Ground lug
Bolt
Aluminum
frame
Nut
Spring washer
Flat washer
Star washer
Ground lug
Bolt
Aluminum
frame
Nut
Spring washer
Flat washer
Ground conductor
Cup washer
Star washer
Aluminum frame
Flat washer
Bolt
Nut
Spring washer
Flat washer
Ground conductor
Cup washer
Star washer
Aluminum frame
Flat washer
Bolt
Wire binding nut
Wire bolt
Ground conductor
Aluminum frame
Mounting
washer nut
Ground conductor
Star washer
Ground lug
Aluminum frame
Tapping screw
Spring washer
