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Last revised: May 17, 2013
4
Chapter 2
Chapter 2
Chapter 2
Chapter 2 Electrical C
Electrical C
Electrical C
Electrical Characteristics
haracteristics
haracteristics
haracteristics of PV M
of PV M
of PV M
of PV Mo
o
o
odule
dule
dule
dule
The module electrical ratings are measured under Standard Test Conditions (STC) of
1000W/m2 irradiance with AM 1.5G spectrum and a cell temperature of 25ºC. Electrical
characteristics of BenQ Solar modules vary slightly by wattage; refer to table below.
Module Type
Module Type
Module Type
Module Type
Pmax
Pmax
Pmax
Pmax
(W)
(W)
(W)
(W)
Voc
Voc
Voc
Voc
(V)
(V)
(V)
(V)
Isa
Isa
Isa
Isa
(A)
(A)
(A)
(A)
Vmp
Vmp
Vmp
Vmp
(V)
(V)
(V)
(V)
Imp
Imp
Imp
Imp
(A)
(A)
(A)
(A)
PM245P01 245
245
37.2
8.64
30.3
8.09
PM245P01 250
250
37.4
8.69
30.6
8.17
PM245P01 255
255
37.6
8.76
30.8
8.28
PM245P01 260
260
37.7
8.83
31.2
8.34
Ref. Table 1
Ref. Table 1
Ref. Table 1
Ref. Table 1 –
––
– Electrical
Electrical
Electrical
Electrical Characteristics by
Characteristics by
Characteristics by
Characteristics by Module Output
Module Output
Module Output
Module Output
A PV module may produce more current and/or voltage than reported at STC. Sunny, cool
weather and reflection from snow or water can increase current and power output.
Therefore, the values of Isc and Voc marked on module should be multiplied by a factor of
1.25 when determining component voltage ratings, conductor capacities, fuse sizes, and size
of controls connected to PV output. An additional 1.25 multiplier may be required by the
NEC (National Electric Code) for sizing fuses and conductors as described in the NEC
section 690-8.
2.1 Performance of PV Modules
A PV module generates current which is proportional to the intensity of solar radiation, and
Direct Current voltage which varies with cell temperatures. The PV cell temperature is
usually higher than the environmental temperature. The increase in the temperature of cell
compared to the air temperature depends on the thermal characteristics of the module.
In summary, depending on solar radiation, the temperature of the cells and the equipment to
which they are connected, a PV module will generate a different current and voltage levels,
which result in a different power output.