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Proceedings Paper

Fabrication and comparison of selective, transparent optics for concentrating solar systems
Author(s): Robert A. Taylor; Yasitha Hewakuruppu; Drew DeJarnette; Todd P. Otanicar
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Paper Abstract

Concentrating optics enable solar thermal energy to be harvested at high temperature (<100oC). As the temperature of the receiver increases, radiative losses can become dominant. In many concentrating systems, the receiver is coated with a selectively absorbing surface (TiNOx, Black Chrome, etc.) to obtain higher efficiency. Commercial absorber coatings are well-developed to be highly absorbing for short (solar) wavelengths, but highly reflective at long (thermal emission) wavelengths. If a solar system requires an analogous transparent, non-absorbing optic – i.e. a cover material which is highly transparent at short wavelengths, but highly reflective at long wavelengths – the technology is simply not available.

Low-e glass technology represents a commercially viable option for this sector, but it has only been optimized for visible light transmission. Optically thin metal hole-arrays are another feasible solution, but are often difficult to fabricate. This study investigates combinations of thin film coatings of transparent conductive oxides and nanoparticles as a potential low cost solution for selective solar covers. This paper experimentally compares readily available materials deposited on various substrates and ranks them via an ‘efficiency factor for selectivity’, which represents the efficiency of radiative exchange in a solar collector. Out of the materials studied, indium tin oxide and thin films of ZnS-Ag-ZnS represent the most feasible solutions for concentrated solar systems. Overall, this study provides an engineering design approach and guide for creating scalable, selective, transparent optics which could potentially be imbedded within conventional low-e glass production techniques.

Paper Details

Date Published: 5 September 2015
PDF: 14 pages
Proc. SPIE 9559, High and Low Concentrator Systems for Solar Energy Applications X, 955905 (5 September 2015); doi: 10.1117/12.2185742
Show Author Affiliations
Robert A. Taylor, The Univ. of New South Wales (Australia)
Yasitha Hewakuruppu, The Univ. of New South Wales (Australia)
Drew DeJarnette, The Univ. of Tulsa (United States)
Todd P. Otanicar, The Univ. of Tulsa (United States)

Published in SPIE Proceedings Vol. 9559:
High and Low Concentrator Systems for Solar Energy Applications X
Adam P. Plesniak; Andru J. Prescod, Editor(s)

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