Solar Radiation Research Laboratory Photographs
The Solar Radiation Research Laboratory (SRRL) houses more than 70 instruments to analyze and record solar radiation and surface meteorology data. Learn more about this equipment by exploring the photographs below. Click on a thumbnail to view the full image.
The SRRL is located on South Table Mountain in Golden, Colorado, at 39.74° N, 105.18° W, and 1,829 m AMSL.
The SRRL's instrument deck is 96 ft long and 16 feet wide.
These two SRRL pyrheliometers are mounted to automatically track the sun for continuous monitoring of direct-normal solar irradiance. These thermopile-based radiometers have a uniform spectral response of 280–2,800 nm and a 5.7° field of view.
This pyranometer is used to measure total hemispheric solar irradiance from 280 to 2,800 nm as part of the SRRL Baseline Measurement System.
This all-sky photograph was taken at the SRRL under partly cloudy conditions. The 8-mm camera lens approximates the 2p steradian field of view of a pyranometer.
This pyranometer is mounted under an automatic shading disk to measure diffuse horizontal solar irradiance.
A shading disk blocks the direct-normal irradiance from a pyranometer receiver to create a measurement of diffuse horizontal or sky irradiance.
This pyranometer is mounted under an adjustable shading band to measure diffuse horizontal solar irradiance.
Shading bands are adjusted daily for the changing solar declination angle to match the path of the sun across the sky. A shadowband correction factor must be applied to pyranometer measurements to account for the portion of the sky blocked by the band.
These pyranometers and pyrheliometer are positioned in a typical arrangement for independent measurements of global, direct, and diffuse solar irradiance. Note that the global pyranometer is not obstructed by the other instruments.
The SRRL Baseline Measurement System collects direct normal and global horizontal solar irradiance from instruments with red Schott glass filters. These colored filters have a cut-on wavelength at 780 nm. The difference between filtered and unfiltered data can be used to estimate the atmospheric precipitable water vapor content.
The SRRL Baseline Measurement System collects the global irradiance on a south-facing surface tilted 40° from horizontal. These data are used to estimate the energy available to a fixed flat-plate solar collector positioned for optimal annual performance.
The SRRL Baseline Measurement System collects the reflected solar irradiance from an inverted pyranometer 1.5 m above the surface. Previous research support included the irradiance distributions on vertical surfaces for model evaluations.
The SRRL Baseline Measurement System collects 5-minute averages of the total ultraviolet portion (295–385 nm) of the solar spectrum. Here, a total ultraviolet radiometer is mounted on a solar tracker and fitted with a view-limiting tube to measure the direct-normal component (a 5.7° full angle). A second photometer (not shown) is mounted on a fixed, horizontal surface for the total hemispheric measurement of ultraviolet radiation.
A pyranometer mounted on an automatic solar tracker provides measurements of the global-normal solar irradiance to estimate the performance of a tracking flat-plate collector.
Broadband Outdoor Radiometer Calibration is routinely performed at the SRRL. All types of pyranometers and pyrheliometers are calibrated to the World Radiometric Reference maintained by the World Radiation Center in Davos, Switzerland.
An absolute cavity radiometer is used to transfer the World Radiometric Reference to all radiometers calibrated at the SRRL. This electrically self-calibrating instrument is one of several used by NREL to maintain calibration traceability to the World Radiometric Reference.
The receiver of an absolute cavity radiometer is carefully constructed and characterized to allow a measurement uncertainty of less than 0.5%. This is the basis of the World Radiometric Reference.
Daily maintenance of all instruments in the SRRL Baseline Measurement System ensures research-quality data. Weather conditions and maintenance activities are recorded for reference and the assessment of data quality.
A rotating shadowband radiometer uses a fast-response, silicon-based detector to measure the global and diffuse irradiance and compute the direct-normal component.
