Environmental Engineering Reference
In-Depth Information
Table 4.3 Two-diode Parameters for Various Photovoltaic Modules
Parameter
c 0
I S1
I S2
m 1
m 2
R S
R P
m 2 /V
µ
Unit
nA
A
-
-
m
AEG PQ
40/50
2.92·10 -3
1.082
12.24
1
2
13.66
34.9
Siemens
M50
3.11·10 -3
0.878
12.71
1
2
13.81
13.0
Kyocera
LA441J59
3.09·10 -3
1.913
8.25
1
2
12.94
94.1
Source: University of Oldenburg, 1994
the first diode. Both diodes have different saturation currents and diode
factors. Thus, the implicit equation for the two-diode model becomes:
(4.39)
The first diode is usually an ideal diode ( m 1 = 1). The diode factor of the
second diode is m 2 = 2. Table 4.3 summarizes parameters that have
demonstrated good simulation results for some modules.
Two-diode model with extension term
The equivalent circuit of the solar cell must be extended for the description of
the negative breakdown characteristics at high negative voltages to be able to
model the complete I-V characteristics. The additional current source I ( V D ) in
Figure 4.19 expresses the extension term, which describes the diode
breakdown in the negative voltage range.
This current source generates a current depending on the diode voltage
V D . This current describes the electrical solar cell behaviour at negative
voltages. With the breakdown voltage V Br , the avalanche breakdown exponent
n and the correction conductance b , the equation for the I-V characteristics
becomes:
(4.40)
 
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