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ratings and capacities. Depending on your local
regulations, an additional 1.25 multiplier forthe
Isc(giving a total multiplier of 1.56) may be
applicable when sizing conductors and fuses.
Table 3 Correction factor of Voc at low temperature
Lowest Estimated
Ambient
Temperature(℃)
24 ~20
19 ~15
14 ~10
9 ~5
4~0
-1 ~-5
-6 ~-10
-11 ~-15
-16 ~-20
-21 ~-25
-26 ~-30
-31 ~-35
-36 ~-40
Alternatively, a more accurate correction factor for
the Voc can be calculated using the following
formula:
α
C
=1-
voc
Voc
C
Where:
is the correction factor of
voc
(%/°C) is the open-circuit voltage temperature
coefficient of the selected module (refer to
corresponding datasheet).T
lowest ambient temperature at the system
installation site.
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16
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Correction
factor
1.02
1.04
1.06
1.08
1.10
1.12
1.14
1.16
1.18
1.20
1.21
1.23
1.25
x（25-T
）
min
α
.
V
oc
Voc
(°C) is the expected
min
The string voltage must not be higher than the
maximum system voltage, as well as the maximum
input voltage of the inverter and other electrical
equipment installed in the system. To ensure the
above requirements, the open-circuit voltage of
the string needsto be calculated using the
following formula:
Maximum system voltage≥N*
Where: N is the number of PV modules in a single
string. V
is the open-circuit voltage of each PV
oc
module (refer to the nameplate or product
datasheet).
Depending on the maximum fuse
ratings of the PV module, and the
local
standards,
parallel strings of PV modules needs to be
equipped with suitable fuses or preventive diodes
for
circuit
protection
calculations and design must be performed by a
competent engineer or consultant.
The IEC & UL standard maximum system voltage for
the regular module series is 1500V according to the
requirements. The IEC & UL standard maximum
system voltage for half-cell module series is 1500V.
The maximum voltage of the system must be less
than the maximum certified voltage and the
maximum input voltage of the inverter and of the
other electrical devices installed in the system.
To calculate the maximum number of connections of
a series of PV modules, the following formula can be
used:
N = 1500V / (V
OC
which shall consider the lowest on-site temperature.
In the formula，1500V is the system voltage, V
V
*C
oc
voc
electrical
installation
the
connection
purposes.
Electrical
* (1+(T
-25℃) * x%)
min
of
is
OC
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