Development of a very fast spectral response measurement system for silicon thin film modules
Nowadays it is possible to built a very fast spectral response (VFSR) measurement system by illuminating simultaneously the solar cell at multiple well defined wavelengths. This can be done by means of light emitting diodes (LEDs) available for a multitude of wavelengths, operating at different stimulation frequencies and analysis of the Fourier Transform of the generated solar cell current. For the purpose to measure the spectral response (SR) of silicon thin film solar cells a detailed characterization of LEDs emitting in the wavelength range from 300 nm to 1000 nm was performed. A VFSR equipment has been built implementing a selection of these LEDs and the difference of the short circuit current density (Jsc) determined from the SR with the VFSR results in about 1.8% in comparison to a conventional SR system with monochromator and lock-in amplifier technology. We have performed Jsc mappings in mini modules 10 cm × 10 cm with the VFSR system with the aim to show the potential and obstacles to perform Jsc mappings.
keywords: solar cell, amorphous silicon, spectral response, LED