Solar spectral irradiance at ground level

Available quantitative data on solar total and spectral irradiance is examined in the context of utilization of solar irradiance for terrestrial applications of solar energy. A brief review is given on the extraterrestrial solar total and spectral irradiance values. Computed values of solar spectral irradiance at ground level for different air mass values and various levels of atmospheric pollution or turbidity are also presented. Wavelengths are given for computation of solar absorptance, transmittance and reflectance by the 100-selected-ordinate method and by the 50-selected-ordinate method from air mass two solar spectral irradiance for the four degrees of atmospheric pollution. Total solar spectral irradiance measured with a prism monochromator is examined to evaluate the direct solar spectral irradiance for a surface normal to the sun's rays and to compare the computed spectrum with the experimentally observed one.