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Cosine Response
Mean cosine response of eleven
Larson
silicon-cell pyranometers (error bars
represent two standard deviations
above and below mean). Cosine
response measurements were made
during broadband outdoor radiometer
calibrations (BORCAL) performed during
two different years at the National
Renewable Energy Laboratory (NREL) in
Golden, Colorado. Cosine response was
calculated as the relative difference of
pyranometer sensitivity at each solar
zenith angle to sensitivity at 45° solar
zenith angle. The blue symbols are AM
measurements, the red symbols are PM
measurements.
Directional, or cosine, response is defined as the
measurement error at a specific angle of radiation
incidence. Error for
Larson
silicon-cell pyranometers is
approximately ± 2 % and ± 5 % at solar zenith angles of
45° and 75°, respectively.
Larson Electronics, LLC
Phone: (800) 369-6671
Fax: (903) 498-3364
www.larsonelectronics.com