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Project 'Colored solar collectors' - Annual report 2005

Abstract

The architectural integration of thermal solar collectors into buildings is often limited by their black color, and the visibility of tubes and corrugations of the absorber sheets. A certain freedom in color choice would be desirable, but the colored appearance should not cause excessive performance degradation. Multilayered thin film interference filters on the collector glazing can produce a colored reflection, hiding the corrugated metal sheet, while transmitting the non-reflected radiation entirely to the absorber. These interference filters are designed and optimized by numerical simulation and shall be manufactured by the sol-gel dip-coating process. The proposed colored glazed solar collectors will be ideally suited for architectural integration into buildings, e.g. as solar active glass facades. The availability of thin film materials with a refractive index lower than that of silicon favors a higher solar transmission at a given value of visible reflectance. The feasibility of the sol-gel deposition of such low refractive index materials has been demonstrated. For the development of nanostructured materials, analytical methods such as electron microscopy are extremely helpful. Important techniques of substrate pretreatment, sample cleaving, polishing, mounting, and microscope handling have been acquired. First measurements yield images of nanostructures produced by the sol-gel dip-coating process. Nanocomposite Ti{sub  More>>
Publication Date:
Dec 15, 2005
Product Type:
Technical Report
Report Number:
SFOE-250184
Subject:
36 MATERIALS SCIENCE; 14 SOLAR ENERGY; SOLAR COLLECTORS; SOLAR ABSORBERS; GLASS; OPTICAL FILTERS; INTERFERENCE; COATINGS; THIN FILMS; STACKS; DEPOSITION; SOL-GEL PROCESS; NANOSTRUCTURES; MATERIALS; SILICON OXIDES; TITANIUM OXIDES; BENCH-SCALE EXPERIMENTS; CHEMICAL PREPARATION; TESTING; PROGRESS REPORT; SOLAR ARCHITECTURE; COMPUTERIZED SIMULATION; DIP COATING
Sponsoring Organizations:
Swiss Federal Office of Energy, Berne (Switzerland)
OSTI ID:
22122484
Research Organizations:
Swiss Federal Institute of Technology (EPFL), Laboratoire d'Energie Solaire et de Physique du Batiment LESO-PB, Lausanne (Switzerland)
Country of Origin:
Switzerland
Language:
English
Other Identifying Numbers:
TRN: CH11E1067
Availability:
Commercial reproduction prohibited. Available from ETDE as OSTI ID: 22122484;
Submitting Site:
CH
Size:
15 page(s)
Announcement Date:
Aug 29, 2013

Citation Formats

Schueler, A., Chambrier, E. De, Roecker, Ch., and Scartezzini, J. -L. Project 'Colored solar collectors' - Annual report 2005. Switzerland: N. p., 2005. Web.
Schueler, A., Chambrier, E. De, Roecker, Ch., & Scartezzini, J. -L. Project 'Colored solar collectors' - Annual report 2005. Switzerland.
Schueler, A., Chambrier, E. De, Roecker, Ch., and Scartezzini, J. -L. 2005. "Project 'Colored solar collectors' - Annual report 2005." Switzerland.
@misc{etde_22122484,
title = {Project 'Colored solar collectors' - Annual report 2005}
author = {Schueler, A., Chambrier, E. De, Roecker, Ch., and Scartezzini, J. -L.}
abstractNote = {The architectural integration of thermal solar collectors into buildings is often limited by their black color, and the visibility of tubes and corrugations of the absorber sheets. A certain freedom in color choice would be desirable, but the colored appearance should not cause excessive performance degradation. Multilayered thin film interference filters on the collector glazing can produce a colored reflection, hiding the corrugated metal sheet, while transmitting the non-reflected radiation entirely to the absorber. These interference filters are designed and optimized by numerical simulation and shall be manufactured by the sol-gel dip-coating process. The proposed colored glazed solar collectors will be ideally suited for architectural integration into buildings, e.g. as solar active glass facades. The availability of thin film materials with a refractive index lower than that of silicon favors a higher solar transmission at a given value of visible reflectance. The feasibility of the sol-gel deposition of such low refractive index materials has been demonstrated. For the development of nanostructured materials, analytical methods such as electron microscopy are extremely helpful. Important techniques of substrate pretreatment, sample cleaving, polishing, mounting, and microscope handling have been acquired. First measurements yield images of nanostructures produced by the sol-gel dip-coating process. Nanocomposite Ti{sub x}Si{sub 1-x}O{sub 2} thin films provide a large range of refractive indices. Aiming a high efficiency of the colored reflection, Ti{sub x}Si{sub 1-x}O{sub 2} based multilayered coatings have been designed and subsequently prepared by sol-gel dip-coating. The energy efficiency M = R{sub VIS}/(100%-T{sub sol}) of the obtained colored reflection amounts up to 2.4. For a convincing demonstration sufficiently large samples of high quality are imperatively needed. An infrastructure for the handling of A4 sized samples has been established regarding substrate cleaning, multiple dip-coating and dust protected thermal annealing. All aspects of the cyclic process for multilayer deposition has been optimized yielding homogenous coatings free of visible defects on a size scale suitable for demonstration (A4). One of the main technical risks of the project is now under control. (authors)}
place = {Switzerland}
year = {2005}
month = {Dec}
}