Parametrization of solar spectral irradiance between 300 and 1100 nm for photovoltaic devices

Abstract

Most solar cells use the solar irradiance at a spectral region between 300 and 1100 nm to generate electricity. We refer to this irradiance as a cell band irradiance (CBI). However, solar energy power systems use the global horizontal irradiance (GHI) to manage the electricity generation rather than the CBI. This is because the CBI is generally not available from either observation or radiation modelling. We conduct a theoretical investigation to show that the ratio of the CBI to GHI varies significantly with atmospheric conditions, which means that using the GHI to manage the electricity generation will introduce a large uncertainty. In this article, we develop a parametrization of irradiance ratio as a function of water vapour, solar zenith angle, aerosol and cloud optical depth, which can be used to convert the GHI to the CBI used by solar cells. We further evaluate this parametrization using the high spectral resolution Rotating Shadowband Spectroradiometer (RSS) data measured at the Southern Great Plains (SGP) site of the US Department of Energy Atmospheric Radiation Measurement (ARM) programme. The results show that the parametrization is reasonably accurate in both clear‐ and all‐sky conditions. The relative mean biases for the estimated clear‐sky GHI and CBI are 1.50 and −0.44%, respectively. The relative r.m.s. differences are 7.38 and 7.68%. The relative mean biases for the estimated all‐sky GHI and CBI are −4.25 and −3.31%, and the relative r.m.s. differences are 16.04 and 18.48%, respectively.