PV*SOL Expert 6.0 - Manual - Valentin Software

13.2.2 Module Part Load Operation
The module’s operation under part load conditions is calculated from the specifications for
no-load voltage, short circuit current, MPP voltage and MPP current with low irradiation
and a module temperature of 25°C.
The second working point, ie the choice of irradiation level, has to be set under certain
restrictions. It must be selected so that, at the irradiation point set, the fill factor is at
maximum, or so that, with lower irradiation, the fill factor becomes considerably smaller
and with higher irradiation the fill factor is around the maximum value.
The definition of the fill factor is:
FF = (MPP current * MPP voltage)
/ (short circuit current * no-load voltage)
The fill factor (FF) is dependent on the irradiation. If a FF above the irradiation is applied,
this results in the fill factor function. Depending on the module and the irradiation, the FF
is usually set at around 55% and 85%.
If you don’t have any suitable specifications for part load operation, you can run the
calculation with standard values by clicking on the Typical Part Load Operation button.
For most modules, the irradiation at the fill factor maximum is 300 W/m². The fill factor is
set at 5% above the FF under standard test conditions. Linear part load operation is given
for the current.
After you have entered the values for module part load operation, it is essential to take a
look at the efficiency characteristic curve and to test that there are no discrepancies.
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