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Title: Measuring solar reflectance - Part II: Review of practical methods

Abstract

A companion article explored how solar reflectance varies with surface orientation and solar position, and found that clear sky air mass 1 global horizontal (AM1GH) solar reflectance is a preferred quantity for estimating solar heat gain. In this study we show that AM1GH solar reflectance R{sub g,0} can be accurately measured with a pyranometer, a solar spectrophotometer, or an updated edition of the Solar Spectrum Reflectometer (version 6). Of primary concern are errors that result from variations in the spectral and angular distributions of incident sunlight. Neglecting shadow, background and instrument errors, the conventional pyranometer technique can measure R{sub g,0} to within 0.01 for surface slopes up to 5:12 [23 ], and to within 0.02 for surface slopes up to 12:12 [45 ]. An alternative pyranometer method minimizes shadow errors and can be used to measure R{sub g,0} of a surface as small as 1 m in diameter. The accuracy with which it can measure R{sub g,0} is otherwise comparable to that of the conventional pyranometer technique. A solar spectrophotometer can be used to determine R{sub g,0}{sup *}, a solar reflectance computed by averaging solar spectral reflectance weighted with AM1GH solar spectral irradiance. Neglecting instrument errors, R{sub g,0}{sup *} matchesmore » R{sub g,0} to within 0.006. The air mass 1.5 solar reflectance measured with version 5 of the Solar Spectrum Reflectometer can differ from R{sub g,0}{sup *} by as much as 0.08, but the AM1GH output of version 6 of this instrument matches R{sub g,0}{sup *} to within about 0.01. (author)« less

Authors:
; ;  [1]
  1. Heat Island Group, Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States)
Publication Date:
OSTI Identifier:
21337927
Resource Type:
Journal Article
Journal Name:
Solar Energy
Additional Journal Information:
Journal Volume: 84; Journal Issue: 9; Other Information: Elsevier Ltd. All rights reserved; Journal ID: ISSN 0038-092X
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; HEAT GAIN; SPECTROPHOTOMETERS; ERRORS; REFLECTIVITY; SPECTRAL REFLECTANCE; RADIANT FLUX DENSITY; SPECTRA; ANGULAR DISTRIBUTION; ACCURACY; VARIATIONS; SOLAR RADIATION; INCIDENCE ANGLE; ORIENTATION; SPECTRALLY SELECTIVE SURFCES; Pyranometers; Solar spectrophotometers; Solar Spectrum Reflectometers

Citation Formats

Levinson, Ronnen, Akbari, Hashem, and Berdahl, Paul. Measuring solar reflectance - Part II: Review of practical methods. United States: N. p., 2010. Web. doi:10.1016/J.SOLENER.2010.04.017.
Levinson, Ronnen, Akbari, Hashem, & Berdahl, Paul. Measuring solar reflectance - Part II: Review of practical methods. United States. https://doi.org/10.1016/J.SOLENER.2010.04.017
Levinson, Ronnen, Akbari, Hashem, and Berdahl, Paul. 2010. "Measuring solar reflectance - Part II: Review of practical methods". United States. https://doi.org/10.1016/J.SOLENER.2010.04.017.
@article{osti_21337927,
title = {Measuring solar reflectance - Part II: Review of practical methods},
author = {Levinson, Ronnen and Akbari, Hashem and Berdahl, Paul},
abstractNote = {A companion article explored how solar reflectance varies with surface orientation and solar position, and found that clear sky air mass 1 global horizontal (AM1GH) solar reflectance is a preferred quantity for estimating solar heat gain. In this study we show that AM1GH solar reflectance R{sub g,0} can be accurately measured with a pyranometer, a solar spectrophotometer, or an updated edition of the Solar Spectrum Reflectometer (version 6). Of primary concern are errors that result from variations in the spectral and angular distributions of incident sunlight. Neglecting shadow, background and instrument errors, the conventional pyranometer technique can measure R{sub g,0} to within 0.01 for surface slopes up to 5:12 [23 ], and to within 0.02 for surface slopes up to 12:12 [45 ]. An alternative pyranometer method minimizes shadow errors and can be used to measure R{sub g,0} of a surface as small as 1 m in diameter. The accuracy with which it can measure R{sub g,0} is otherwise comparable to that of the conventional pyranometer technique. A solar spectrophotometer can be used to determine R{sub g,0}{sup *}, a solar reflectance computed by averaging solar spectral reflectance weighted with AM1GH solar spectral irradiance. Neglecting instrument errors, R{sub g,0}{sup *} matches R{sub g,0} to within 0.006. The air mass 1.5 solar reflectance measured with version 5 of the Solar Spectrum Reflectometer can differ from R{sub g,0}{sup *} by as much as 0.08, but the AM1GH output of version 6 of this instrument matches R{sub g,0}{sup *} to within about 0.01. (author)},
doi = {10.1016/J.SOLENER.2010.04.017},
url = {https://www.osti.gov/biblio/21337927}, journal = {Solar Energy},
issn = {0038-092X},
number = 9,
volume = 84,
place = {United States},
year = {Wed Sep 15 00:00:00 EDT 2010},
month = {Wed Sep 15 00:00:00 EDT 2010}
}