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Applied Optics

Applied Optics


  • Vol. 38, Iss. 19 — Jul. 1, 1999
  • pp: 4189–4197

Angular solar absorptance of absorbers used in solar thermal collectors

Tuquabo Tesfamichael and Ewa Wäckelgård  »View Author Affiliations

Applied Optics, Vol. 38, Issue 19, pp. 4189-4197 (1999)

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The optical characterization of solar absorbers for thermal solar collectors is usually performed by measurement of the spectral reflectance at near-normal angle of incidence and calculation of the solar absorptance from the measured reflectance. The solar absorptance is, however, a function of the angle of incidence of the light impinging on the absorber. The total reflectance of two types of commercial solar-selective absorbers, nickel-pigmented anodized aluminum, and sputtered nickel/nickel oxide coated aluminum are measured at angles of incidence from 5° to 80° in the wavelength range 300–2500 nm by use of an integrating sphere. From these measurements the angular integrated solar absorptance is determined. Experimental data are compared with theoretical calculations, and it is found that optical thin-film interference effects can explain the significant difference in solar absorptance at higher angles for the two types of absorbers.

© 1999 Optical Society of America

OCIS Codes
(160.1190) Materials : Anisotropic optical materials
(260.3160) Physical optics : Interference
(310.1620) Thin films : Interference coatings
(310.6860) Thin films : Thin films, optical properties
(310.6870) Thin films : Thin films, other properties
(350.6050) Other areas of optics : Solar energy

Original Manuscript: December 15, 1998
Revised Manuscript: April 13, 1999
Published: July 1, 1999

Tuquabo Tesfamichael and Ewa Wäckelgård, "Angular solar absorptance of absorbers used in solar thermal collectors," Appl. Opt. 38, 4189-4197 (1999)

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