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Title: Comparison of the effect of outdoor exposure on the optical properties of solar mirrors and transparent encapsulant materials

Abstract

The effects of outdoor exposure on solar mirrors and transparent encapsulant materials are assessed and compared. The encapsulant materials tested included glasses, polymers and silicones. Samples of the materials were placed on stationary exposure racks in six locations that represented urban, desert, oceanside and high altitude mountain areas. Samples were removed periodically for optical characterizations. The spectral hemispherical and diffuse reflectance of the mirror samples and the spectral hemispherical transmittance and diffuse reflectance of the encapsulant materials was measured. The relative normal hemispherical transmittance of the encapsulant materials was measured. Correlations between the glass and mirror data showed that the average diffuse reflectance losses were six times larger for the mirrors than for the glass samples. The average specular reflectance losses for the mirror samples were seven times as large as the average hemispherical transmittance losses for the glass samples. These correlations may enable one to predict the performance of mirrors made using the other encapsulant materials for superstrates. It was found that the urban and oceanside sites were the dirtiest, while the desert and mountain sites were the cleanest. Average specular reflectance losses varied from 4% at the cleanest site to 50% at the dirtiest site. The range inmore » hemispherical transmittance losses for the encapsulant materials varied between 0% and 6%. At one site, the average daily specular reflectance losses were .04% for the mirror samples and average daily hemispherical transmittance losses were about .01% for the glass samples. The polymer materials degraded somewhat more rapidly than the glasses, and the silicones irreversible degraded too rapidly and severely to be useful for either photovoltaic or solar thermal applications.« less

Authors:
; ;
Publication Date:
Research Org.:
Battelle Pacific Northwest Labs., Richland, WA (United States)
OSTI Identifier:
5283302
Report Number(s):
PNL-4074
ON: DE82005863
DOE Contract Number:  
AC06-76RL01830
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; GLASS; OPTICAL PROPERTIES; WEATHERING; MIRRORS; MATERIALS TESTING; POLYMERS; CONTAMINATION; DESERTS; ENCAPSULATION; LIGHT TRANSMISSION; MOUNTAINS; SEAS; SILICONES; SPECTRAL REFLECTANCE; URBAN AREAS; ARID LANDS; PHYSICAL PROPERTIES; SILOXANES; SURFACE WATERS; TESTING; 141000* - Solar Collectors & Concentrators

Citation Formats

Dake, L S, Lind, M A, and Maag, C R. Comparison of the effect of outdoor exposure on the optical properties of solar mirrors and transparent encapsulant materials. United States: N. p., 1981. Web. doi:10.2172/5283302.
Dake, L S, Lind, M A, & Maag, C R. Comparison of the effect of outdoor exposure on the optical properties of solar mirrors and transparent encapsulant materials. United States. https://doi.org/10.2172/5283302
Dake, L S, Lind, M A, and Maag, C R. 1981. "Comparison of the effect of outdoor exposure on the optical properties of solar mirrors and transparent encapsulant materials". United States. https://doi.org/10.2172/5283302. https://www.osti.gov/servlets/purl/5283302.
@article{osti_5283302,
title = {Comparison of the effect of outdoor exposure on the optical properties of solar mirrors and transparent encapsulant materials},
author = {Dake, L S and Lind, M A and Maag, C R},
abstractNote = {The effects of outdoor exposure on solar mirrors and transparent encapsulant materials are assessed and compared. The encapsulant materials tested included glasses, polymers and silicones. Samples of the materials were placed on stationary exposure racks in six locations that represented urban, desert, oceanside and high altitude mountain areas. Samples were removed periodically for optical characterizations. The spectral hemispherical and diffuse reflectance of the mirror samples and the spectral hemispherical transmittance and diffuse reflectance of the encapsulant materials was measured. The relative normal hemispherical transmittance of the encapsulant materials was measured. Correlations between the glass and mirror data showed that the average diffuse reflectance losses were six times larger for the mirrors than for the glass samples. The average specular reflectance losses for the mirror samples were seven times as large as the average hemispherical transmittance losses for the glass samples. These correlations may enable one to predict the performance of mirrors made using the other encapsulant materials for superstrates. It was found that the urban and oceanside sites were the dirtiest, while the desert and mountain sites were the cleanest. Average specular reflectance losses varied from 4% at the cleanest site to 50% at the dirtiest site. The range in hemispherical transmittance losses for the encapsulant materials varied between 0% and 6%. At one site, the average daily specular reflectance losses were .04% for the mirror samples and average daily hemispherical transmittance losses were about .01% for the glass samples. The polymer materials degraded somewhat more rapidly than the glasses, and the silicones irreversible degraded too rapidly and severely to be useful for either photovoltaic or solar thermal applications.},
doi = {10.2172/5283302},
url = {https://www.osti.gov/biblio/5283302}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Sep 01 00:00:00 EDT 1981},
month = {Tue Sep 01 00:00:00 EDT 1981}
}