The influence of spectral solar irradiance variations on the performance of selected single-junction and multijunction solar cells

The sensitivities of selected single-junction and multijunction cells to variations in solar irradiance are presented. The one-sun spectral irradiance is varied as a function of air mass, optical aerosol depth (turbidity) and amount of precipitable water vapor for direct-normal and global-normal geometries. Several devices, including one-, two- and three-junction devices with low and high bandgaps and either series- or independent-connection schemes, were investigated. The effects of air mass and turbidity on the consistency of high-bandgap device performance are shown to be greater than the effect of precipitable water vapor. Low-bandgap devices are less affected by variations in air mass and turbidity, but are more sensitive to high water-vapor conditions. The efficiency gained by redesigning a multijunction device for the latitude at which it is expected to be used is shown to be less than about 3% (relative).