Modelling the realistic short circuit current and MPP power of a-Si single and multi-junction devices

An I-V based model for amorphous silicon materials is presented that allows for the modelling of spectral effects on the performance of a-Si devices. These have been shown to be significant in colder and temperate climates. A simple model for the influence of varying spectra on the short circuit current is presented. It allows for accurate modelling of other device parameters such as MPP-power. The necessary spectral input for this model is generated by a model based on artificial neural network using the clear sky index and position of the Sun as input. The model is developed using long-term measurements taken at Loughborough and shows a good agreement for single and multi-junction devices.