Reflective coatings for large-area solar concentrators

Journal Article · Wed May 01 04:00:00 EDT 1996 · Journal of Vacuum Science and Technology, A

DOI:https://doi.org/10.1116/1.580378· OSTI ID:284650

Martin, P M; Affinito, J D; Gross, M E; Stewart, D C; Bennett, W D ^[1]; Kelley, R J ^[2]; Horne, W E ^[3]

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1. Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)
2. United Solar Technologies, Olympia, Washington 98506 (United States)
3. EDTEK, Inc., Kent, Washington 98032 (United States)

Reflective/protective coatings were applied to pre-formed 2.5-m-long solar concentrator panels by the magnetron sputtering process. Low-cost manufacturing processes such as hydrostatic forming of aluminum solar concentrator panels are needed to keep the costs of domestic power generation low. Without treatment, the specular reflectance of the aluminum panels was less than 20{percent}. As expected, silver (Ag) and aluminum (Al) coatings applied directly over the untreated panels did not significantly increase specular reflectance. To provide a specular base surface, approximately 100-{mu}m-thick urethane layers were applied to the panels before deposition of the reflective coating. This smoothing layer filled in scratches and defects. Reflective Ag and Al layers, with protective overcoats of Al{sub 2}O{sub 3} and Si{sub 3}N{sub 4}, were deposited onto the urethane-coated panels by reactive magnetron sputtering with ion assist in Pacific Northwest National Laboratory{close_quote}s 3 m coating chamber. The specular reflectance of the panels increased to an average of 92{percent} at visible wavelengths, very near the reflectance of Al coatings on highly polished glass. Panels with Ag metal layers displayed similar increases. The optical performance uniformity of the coating was better than {plus_minus}5{percent}. The measured primary concentration ratio of the panels was 800:1, which far exceeded the design ratio of 500:1. The total concentration ratio was 2400:1. The coatings passed MIL-spec environmental and durability tests. Field testing of the concentrator dishes and coatings is continuing, and test results will be reported. {copyright} {ital 1996 American Vacuum Society}

• OSTI ID: 284650
• Report Number(s): CONF-9510385--
• Journal Information: Journal of Vacuum Science and Technology, A, Journal Name: Journal of Vacuum Science and Technology, A Journal Issue: 3 Vol. 14; ISSN 0734-2101; ISSN JVTAD6
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
36 MATERIALS SCIENCE
ALUMINIUM
ALUMINIUM OXIDES
DEPOSITION
PROTECTIVE COATINGS
REFLECTIVE COATINGS
REFLECTIVITY
SILICON NITRIDES
SILVER
SOLAR CONCENTRATORS
SPUTTERED MATERIALS
TESTING