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Proceedings Paper

Spectrally Selective Surfaces For High-Temperature Photothermal Solar Energy Conversion
Author(s): Keith D. Masterson
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Paper Abstract

A selective surface that absorbs the incident solar energy but suppresses its thermal reradiation can in some cases substantially improve the efficiency of a solar energy converter. In high-temperature applications, selective surfaces are shown to be most beneficial to systems using low or intermediate concentration ratios, although substantial economic savings can arise when used with large power systems having high concentration ratios. The optical performance and high temperature stability are discussed for coatings that rely on each of the five different methods for producing spectral selectivity. Each method has disadvantages as well as advantages, with most of the successful coatings using two or more of the methods. A particular coating that utilizes a silicon absorber over a silver reflector layer is described. The silicon is added by chemical vapor deposition (CVD) at elevated temperatures (>600°C). This is a unique application for CVD and has the potential for large-scale production in a flow-through system. At 500°C the solar absorptance and total normal emittance for these coatings are 0.76 and 0.07, respectively. They have withstood lifetime testing for 1000 hours of cycling (2/h) between 150°C and 450°C, plus 100 h continuously at 600°C with little degradation. Future improvements should allow the entire stack to be fabricated by CVD and at the same time achieve increases in both optical performance and high-temperature durability.

Paper Details

Date Published: 16 March 1976
PDF: 7 pages
Proc. SPIE 0068, Optics in Solar Energy Utilization I, (16 March 1976); doi: 10.1117/12.978113
Show Author Affiliations
Keith D. Masterson, University of Arizona (United States)

Published in SPIE Proceedings Vol. 0068:
Optics in Solar Energy Utilization I
Yale Katz, Editor(s)

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