Towards a fully LED-based solar simulator - spectral mismatch considerations

LED solar simulators have a high potential for high quality characterisation of solar cells. One of the main challenges is to achieve a close spectral match to the AM1.5 solar spectrum from 350nm to 1300nm. The main sources of measurement uncertainty are the spectral mismatch, the non-uniformity of light and the reference cell. The spectral mismatch can increase the measurement uncertainty significantly. In order to minimize a major uncertainty factor a close spectral match needs to be acquired. It will be shown that the usage of LEDs, which are narrow wavelength emitting light sources, can improve the measurement accuracy of the solar simulator by accurately matching the solar spectrum. The process of choosing the best combination of wavelengths and the LED population per wavelength is a complex, dual optimization problem. This paper evaluates the optimisation algorithms chosen and examines the influence of different fitness functions in acquiring a Class A+ spectral match.