9.1
9.1.1
9.1.2
9
Solar Cell Parameters and Equivalent
Circuit
External solar cell parameters
The main parameters that are used to characterize the performance of solar cells are the
peak power P max , the short circuit current density J sc , the open circuit voltage V oc , and the
fill factor FF. These parameters are determined from the illuminated J-V characteristic as
illustrated in Figure 8.10. The conversion efficiency η can be determined from these
parameters.
Standard test conditions
For a reliable measurement of the J-V characteristics, it is vital to perform the
measurements under standard test conditions (STC). This means that the total irradiance
on the solar cell that should be measured is equal to 1000 W/m
2 . Further, the spectrum
should resemble the AM1.5 spectrum that we discussed in Section 5.5. Additionally, the
temperature of the solar cell should be kept constant at 25 °C. As we will see in Section
20.3, the performance of a solar cell strongly depends on the temperature.
Short circuit current density
The short circuit current I sc is the current that flows through the external circuit when the
electrodes of the solar cell are short circuited. The short circuit current of a solar cell
depends on the photon flux incident on the solar cell, which is determined by the spectrum
of the incident light. For standard solar cell measurements, the spectrum is standardized to
the AM1.5 spectrum. The I sc depends on the area of the solar cell. In order to remove the
dependence of the solar cell area on I sc , the short-circuit current density is often used to
describe the maximum current delivered by a solar cell. The maximum current that the
solar cell can deliver strongly depends on the optical properties of the solar cell, such as
absorption in the absorber layer and reflection.
9.1.1
9.1.2
9
Solar Cell Parameters and Equivalent
Circuit
External solar cell parameters
The main parameters that are used to characterize the performance of solar cells are the
peak power P max , the short circuit current density J sc , the open circuit voltage V oc , and the
fill factor FF. These parameters are determined from the illuminated J-V characteristic as
illustrated in Figure 8.10. The conversion efficiency η can be determined from these
parameters.
Standard test conditions
For a reliable measurement of the J-V characteristics, it is vital to perform the
measurements under standard test conditions (STC). This means that the total irradiance
on the solar cell that should be measured is equal to 1000 W/m
2 . Further, the spectrum
should resemble the AM1.5 spectrum that we discussed in Section 5.5. Additionally, the
temperature of the solar cell should be kept constant at 25 °C. As we will see in Section
20.3, the performance of a solar cell strongly depends on the temperature.
Short circuit current density
The short circuit current I sc is the current that flows through the external circuit when the
electrodes of the solar cell are short circuited. The short circuit current of a solar cell
depends on the photon flux incident on the solar cell, which is determined by the spectrum
of the incident light. For standard solar cell measurements, the spectrum is standardized to
the AM1.5 spectrum. The I sc depends on the area of the solar cell. In order to remove the
dependence of the solar cell area on I sc , the short-circuit current density is often used to
describe the maximum current delivered by a solar cell. The maximum current that the
solar cell can deliver strongly depends on the optical properties of the solar cell, such as
absorption in the absorber layer and reflection.