Generac Power Systems S2502 Installation Manual page 15

Section 3: Installation Design
Voltage Considerations
Use the formulas in this section to determine the maxi-
mum number of PV modules of a given type that can be
connected to a PV Link. For more detailed information on
array sizing visit www.generac.com.
NOTE: Fewer PV modules may be used providing the
minimum MPPT input voltage is satisfied.
1. See Table 3-1 . Use Equation (1) to calculate the
Adjusted Module Voc for the chosen PV Module.
NOTE: The temperature correction factor listed on
the module nameplate can be used as a substitute
for the NEC Cold Factor if available.
Table 3-1. NEC Cold Factor
Minimum Temperature (°F)
49 to 41
40 to 32
31 to 23
22 to 14
13 to 5
4 to -4
-5 to -13
-14 to -22
-23 to -31
-32 and below
Current Considerations
Ensure that the short circuit current (Isc) of the PV modules are suitable for use with the SnapRS and PV Link per NEC
690.8(A)(1). Refer to product current specifications in
Installation Manual for PV Link and SnapRS Installation Manual
2. Use Equation (2) to determine the Max Number of
Modules Voc, where PV Link Max Voc = 420 VDC.
3. Use Equation (3) to determine the Max Number of
Modules Vmp, where PV Link Max Vmp = 360
VDC.
4. Compare the results from Step 2 and Step 3 and
choose the smaller number. Round down to the
nearest integer. Record this value as the Maximum
number of series connected PV modules.
NEC Cold Factor
1.08
1.10
1.12
1.14
1.16
1.18
1.20
1.21
1.23
1.25
Section 2 General Information.
Installation Design
Minimum Temperature (°C)
9 to 5
4 to 0
-1 to -5
-6 to -10
-11 to -15
-16 to -20
-21 to -25
-26 to -30
-31 to -35
-36 and below
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