FAQ
Solar Simulators
It takes less than one minute to change the lamp and less than five minutes to align the lamp.
A calibrated Reference Cell is created by exposing the cell to a known and calibrated standard one sun light source. The short circuit current (ISC) generated by the Reference Cell is noted under the standard conditions. Once this current value is established, then the Reference Cell is put under the SS light, the current generated is noted and compared to calibration value. If the generated current does not match the calibration value then the light intensity of the SS is adjusted until the generated current matches the calibration value. In general a Reference Cell should be made out of the same material as the cells that are to be tested. If this is not the case, then the spectral mismatch correction factors should be used for more accurate results.
For users that only have Solar Simulators (i.e. no IV Measurement system), a shunted Reference Cell can be used to calibrate the intensity of the Solar Simulator. The shunted Reference Cell has a resistor across the two electrodes of the cell. When the shunted Reference Cell is placed under the light, it generates a signal, typically in mV DC. The value of this resistor is selected such that the output of the Reference Cell is linearly proportional to the intensity of the light.
I-V Measurement Systems
The electronic circuitry should be calibrated periodically. Although the system maintains its calibration for a long period of time, those who are concerned should calibrate annually. The calibration involves using a calibrated voltage and current source. The value of the current-sensing resistor is determined and incorporated into the software as a conversion factor. Also, the value of the voltage division ratio is similarly determined and recorded.
The light intensity should be calibrated frequently. This is performed by measuring the electrical output of a reference cell and comparing the measurement result to the reference calibration value for the test conditions of interest. The lamp power should be adjusted until the reference cell measurement is matches its calibration value.