Accurate Linearity Measurements of the Short-Circuit Current Using a Spectral Shaping Setup

An accurate quantification of the linearity of the short-circuit current with respect to the irradiance is an integral part in the electrical characterisation of solar cells. It is especially important for the calibration of irradiance sensors and reference devices. We demonstrate that an in-house developed spectral shaping setup can reproduce the global AM1.5 solar reference spectrum with a high match. The generated irradiance of < 1 W/m² is perfectly adjusted to conduct a dual beam configuration with a differential measurement technique to measure short-circuit currents in the irradiance range from 0 W/m² to over 1000 W/m². We also investigate the short-circuit current spectrally dependent owing to the freely programmable spectral shaping setup with approximately 1088 accessible spectral subsections in the wavelength range from 355 nm to 1200 nm. Deviations from linearity below 0.1 % are detected on a WPVS solar reference cell demonstrating the high sensitivity of the presented setup. A rear side of a PERC solar cell was investigated to demonstrate the measurement of a strong spectrally dependent nonlinearity of 40 %.