Spectral Dependence of Amorphous Silicon Photovoltaic Device Performance

摘要

The short circuit currents of a single, double and triple junction amorphous silicon (a-Si) device are investigated for changes with spectral irradiance variation. Two effects have been previously identified; a primary spectral effect that depends purely on the availability of spectrally useful irradiance within the absorption band of the device and a secondary effect that depends also on the spectral distribution within this band. The average photon energy (APE) has been introduced as a useful parameter for describing spectra. It is a device independent environmental parameter, which effectively puts a figure to the blueness of a spectrum and readily allows the analysis of spectral effects on photovoltaic devices. Single junction cells have a higher performance as light becomes more blue-shifted. Double and triple junction cells have a performance which is maximised when the received spectrum is matched to the absorption profile and drops off when the radiation is either red- or blue-shifted.