Recent Update of International Standards on Radiometry

Standards With Major Updates and Standards Under Development International radiometric standards serve as the foundation for accuracy and uniformity in solar irradiance measurement. These standards lay out universally accepted protocols for the calibration, classification, and usage of radiometric instruments, such as pyranometers and pyrheliometers, which quantify various aspects of solar radiation, including global horizontal irradiance (GHI), direct normal irradiance (DNI), and diffuse horizontal irradiance (DHI). By adhering to these standards, solar resource measurements become traceable, dependable, and comparable on a global scale. These standards are developed by organizations like the World Meteorological Organization (WMO), the International Organization for Standardization (ISO), and the American Society for Testing and Materials (ASTM). The implementation of radiometric standards is essential for obtaining high-quality data, which are vital for precise solar resource assessments, photovoltaic design, durability studies, and energy yield predictions. The National Renewable Energy Laboratory (NREL) has taken a leading role in various international subcommittees, including the ISO/TC180 SC1 Climate -Measurement and Data and the ASTM G03.09 Radiometry subcommittee. Recently, NREL and its partners have been actively involved in updating and developing multiple standards to incorporate the latest advancements in knowledge, science, and technology.