In 1982, the American Society for Testing and Materials (ASTM) adopted consensus standards for direct-normal and hemispherical ("global") tilted solar terrestrial spectra (ASTM E891/E892/GI59). These standard spectra were intended to evaluate photovoltaic (PV) device performance and other solar-related applications. The International Standards Organization (ISO) and International Electrotechnical Commission (IEC) adopted these spectra as spectral standards ISO 9845-1 and IEC 60904-3. Additional information and more accurately representative spectra are needed by today's PV community. Modern terrestrial spectral radiation models, knowledge of atmospheric physics, and measured radiometric quantities are applied to develop new reference spectra under consideration byASTM.