Yingli Solar PV Modules, Installation and User Manual / page 4
Equipment Grounding
The frame of the PV module, as well as any exposed non-current-carrying
metal parts of fixed equipment that are able to become energized by the
PV system, must be connected to the equipment grounding conductor
in order to prevent electrical shock. Refer to section 250 of the NEC for
specific instructions on grounding. Even when applicable regulations,
code requirements, and standards do not require safety-related
grounding, Yingli Solar recommends grounding all PV module frames in
order to ensure the voltage between electrically conductive equipment
and earth ground is zero in all circumstances.
Proper equipment grounding is achieved by bonding all exposed non-
current-carrying metal equipment continuously to one another using an
appropriately sized equipment grounding conductor (EGC) or racking
system that can be used for integrated grounding (see Option C in
Grounding Methods below).
Yingli Solar PV modules employ a coated aluminum frame for corrosion
resistance. In order to properly ground the module frame, the coating
must be penetrated.
Grounding wire use copper wire with minimum 12 AWG insulated for a
minimum 90
ºC.
The potential for corrosion due to the electrochemical action between
dissimilar metals in contact is minimized if the electrochemical voltage
potential between the dissimilar metals is low. The grounding method
must not result in the direct contact of dissimilar metals with the
aluminum frame of the PV module that will result in galvanic corrosion.
An addendum to UL 1703 recommends metal combinations not exceed
an electrochemical potential difference of 0.5 Volts.
The frame rails have pre-drilled holes marked with a grounding sign,
as illustrated in Figure 7. These holes should be used for grounding
purposes and must not be used for mounting the PV modules. Do not
drill additional holes into the frame rails.
Figure 7: Grounding hole detail
The following grounding methods are available:
Option A: Grounding Lugs
Manufacturer
Part Number
Material
Tightening Torque
ILSCO
GBL-4DBT
Tin-plated copper
20 to 25 in-lbf
(2.3 to 2.6 N∙m)
Burndy
®
CL501-TN
Tin-plated copper
20-25 in-lbf
(2.3 to 2.6 N∙m)
Tyco Electronics
SolKlip
1954381-4
Nickel and
tin-plated copper
15 +4.4/-1.7 in-lbf
(1.7+0.5/-0.2 N∙m)
Table 2: Grounding lug specifications
Installation of grounding lugs must be in accordance with the specified
instructions of the respective manufacturers. A grounding lug must
be attached at a designated grounding hole location using #10
stainless steel hardware. A stainless steel toothed lock washer or KEPS
nut is required to adequately engage the frame and penetrate the
nonconductive coating. The screw holding the appropriately sized
EGC in place must firmly clamp the EGC in order to establish a reliable
electrical bond.
Figure 8: Grounding lug detail
Option B: Screw Assembly
1. A grounding screw assembly must be attached at a designated
grounding hole location using only stainless steel hardware. Insert a
#10 stainless steel screw first through the stainless steel cup washer,
and then through the grounding hole.
2. Loosely engage a stainless steel backing nut and toothed lock washer
to the screw.
3. Bend the EGC into an omega (Ω) shape to tightly fit between the
partially installed screw head and cup washer. The EGC shall be
exclusively in contact with stainless steel.
4. Tighten the screw to 35 in-lbf (4 N∙m) torque. The toothed lock washer
should be visibly engaged to the frame.
5. Route the appropriately sized EGC in such a way as to avoid contact
with the aluminum module frame.
Figure 9: Grounding screw assembly detail
Option C: Racking Manufacturer Integrated
Grounding Methods
Yingli Solar PV modules can be grounded by bonding PV modules to
a grounded racking system. Integrated grounding methods must be
certified to UL 1703 or 2703 for grounding PV modules and must be
installed in accordance with the specified instructions of their respective
manufacturers.
Grounding Holes
ø0.236in (6mm)
PV Laminate
Backing Nut
Toothed Lock Washer or KEPS Nut
Grounding Lug
Equipment
Grounding
Conductor
Aluminum
Frame
Screw
PV Laminate
Backing Nut
Toothed Lock Washer or KEPS Nut
Cup Washer
Aluminum
Frame
Screw
Equipment
Grounding
Conductor
