Sacramento Municipal Utility District (SMUD)
Latitude: 38.54586o North
A rotating shadowband radiometer (RSR) offers a lower cost option of measuring solar radiation resources for renewable energy applications. The RSR uses a silicon-based photodiode pyranometer to measure the global and diffuse solar irradiance. The control and data acquisition system then computes the corresponding direct normal solar irradiance based on the geographic location of the RSR and the time of the data collection events.
By design, the RSRs offer the potential advantages of lower maintenance and calibration costs because they use a single pyranometer with a diffuser for determining the direct, diffuse, and global solar irradiance rather than up to three radiometers with larger optical surfaces, more complex support equipment, or more maintenance-intensive support equipment. Their potential disadvantage is the higher estimated measurement uncertainty because of factors such as the restricted spectral response of the silicon-based detector used in the RSR. Postprocessing software to account for the limited spectral response of the silicon detector has been developed and applied the RSR data. This solar-powered system is simple to operate and provides basic resource information.For more information about the RSR visit Irradiance, Inc.