Environmental Engineering Reference
In-Depth Information
Figure 4.13
Simple Equivalent Circuit of a Solar Cell
E
LECTRICAL
D
ESCRIPTION OF
S
OLAR
C
ELLS
Simple equivalent circuit
A photovoltaic solar cell is a large area
diode
. It consists of an n-type and p-
type doped semiconductor with a resulting space charge layer. Typically, a
non-irradiated solar cell has nearly the same behaviour as a diode. Therefore,
a simple diode can describe the equivalent circuit.
The equation of the cell current
I
depends on the cell voltage (here
V
=
V
D
) with the saturation current
I
S
and the diode factor
m
:
(4.32)
The thermal voltage
V
T
at a temperature of 25°C is
V
T
= 25.7 mV. The
magnitude of the saturation current
I
S
is of the order of 10
-10
-10
-5
A. The
Figure 4.14
Influence of the Irradiance
E
on the I-V Characteristics
of a Solar Cell
