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6
Electrical Installation
6.1
Electrical characteristics
The electrical characteristics are detailed in the PV
module product datasheet.
The rated values of electrical characteristics, including
I
, V
and P
, have some tolerance with the measured
sc
oc
mpp
values at standard condition: ±5% for I
±3.5% for V
and ±3.5% for P
oc
condition refers to 1000W/m
temperature at 25℃.
The actual maximum voltage must be less than the
standard maximum system voltage and the maximum
output voltage of the inverter and other electrical
equipment installed in the system. The number of PV
modules connected in series should match the voltage
specification of the inverter. The total voltage generated
by PV modules in series should not be higher than the
maximum voltage allowed by the system.
To ensure the above requirements, the open-circuit
voltage of the string needs to be calculated at the
lowest expected ambient temperature at certain
location. This can be calculated using the following
formula:
Maximum system voltage≥N*V
25)] Where:
N: number of PV modules in a single string
V
: open-circuit voltage of each PV module (refer to
oc
the PV module nameplate or product manual)
TC
: temperature coefficient of PV module for
voc
open-circuit voltage (refer to the PV module product
13
,
sc
. The standard test
mpp
2
, AM1.5 and cell
*[1+TC
*(T
-
oc
voc
min
manual)
T
: minimum ambient temperature.
min
！ATTENTION
Under normal operating conditions, the output current
and/or voltage of the PV module may be higher than
the value under standard testing conditions. Therefore,
in PV system design, for example determining the rated
voltage of equipment, current carrying capacity of
wires and fuse and parameters associated with the
output power of PV modules, the corresponding short-
circuit current and open-circuit voltage should be
applied with a safety factor of 1.25. The number of PV
modules connected in series should match the voltage
specification of the inverter. The total voltage
generated by the PV modules connected in series
cannot be higher than the maximum voltage allowed by
the system.
Depending on the maximum rated fuse current of the
PV module and the local electrical installation
standards, the connection of parallel strings of PV
modules needs to be equipped with suitable fuses or
preventive diodes for circuit protection purposes.
6.2 Electrical connection
To ensure the normal operation of the system, make sure
the polarity of cables is correct when connecting modules
or loads, such as inverters and batteries. If the PV module
is not connected correctly, the bypass diode may be
damaged. Fig. 14 shows how the PV modules are
connected in series and parallel. PV modules can be wired
in series to boost the voltage. Series connections are made
by connecting the wire from the positive terminal of one
module to the negative terminal of the next module. PV
modules can be wired in parallel to increase the current by
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