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Title: Sensitivity of Spectroradiometric Calibrations in the Near Infrared to Variations in Atmospheric Water Vapor: Preprint

Spectra of natural sunlight and artificial sources are important in photovoltaic research. Calibration of the spectroradiometers used for these measurements is derived from the response to spectral irradiance standards from the National Institute of Standards and Technology (NIST). Some photovoltaic devices respond in the near infrared, or NIR, so spectral measurements and calibrations are needed in this region. Over the course of several calibrations, we identified variations> 5% in spectroradiometer NIR calibration data for a certain spectroradiometer. A detailed uncertainty analysis did not reflect the observed variation. Reviewing calibration procedures and historical data, we noted that the variations were seen in water vapor absorption bands. We used spectral transmission models to compute changes in atmospheric transmission (as a function of water vapor content) over path lengths occurring during calibration. The results indicate that the observed variations result from varying water vapor content. A correction algorithm for adjusting measured data was developed based on our analysis.
Authors:
;
Publication Date:
OSTI Identifier:
15007168
Report Number(s):
NREL/CP-560-36037
TRN: US200414%%344
DOE Contract Number:
AC36-99-GO10337
Resource Type:
Conference
Resource Relation:
Conference: Conference title not supplied, Conference location not supplied, Conference dates not supplied; Other Information: PBD: 1 Mar 2004; Related Information: Prepared for the American Solar Energy Society Annual Conference, 11-14 July 2004, Portland, Oregon
Research Org:
National Renewable Energy Lab., Golden, CO (US)
Sponsoring Org:
US Department of Energy (US)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 47 OTHER INSTRUMENTATION; ABSORPTION; ALGORITHMS; CALIBRATION; SENSITIVITY; SPECTRA; WATER VAPOR; SOLAR ENERGY CALIBRATION OF SPECTRORADIOMETERS; SPECTRAL IRRADIANCE STANDARDS; NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY; PHOTOVOLTAIC RESEARCH; NEAR INFRARED; VARIATIONS IN WATER VAPOR; SOLAR ENERGY - RADIATION