Direct luminous efficacy and atmospheric turbidity - improving model performance

Journal Article · Tue Aug 01 04:00:00 EDT 1995 · Solar Energy

DOI:https://doi.org/10.1016/00380-92X9(50)0035P-· OSTI ID:219850

Molineaux, B; Ineichen, P ^[1]; Delaunay, J J ^[2]

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1. Univ. of Geneva, Conches (Switzerland)
2. Fraunhofer Institut fuer Solare Energiesysteme, Freiburg (Germany)

Of all the atmospheric constituents, aerosol content is shown to be responsible for the greatest variations in direct luminous efficacy. Some clarity is brought to the comparison between Linke`s and Angstrom`s turbidity coefficients, respectively T{sub L} and {Beta}. Grenier`s recent formulation of the optical thickness of a water and aerosol free atmosphere is presented here in a simplified expression. Based on these results and Dogniaux`s illuminance turbidity factor, T{sub il}, two direct luminous efficacy models are derived, one of which is tuned to our experimental data. The input parameters are optical air mass, {Beta}, and water vapor content in the tuned version. These models perform significantly better than any of twelve other models found in the literature when compared to 1 yr`s measurements from each of two sites in the U.S. and Switzerland. In both sites, {Beta} was derived from horizontal visibility estimated in a nearby airport. 43 refs., 5 figs., 2 tabs.

• Sponsoring Organization: USDOE
• OSTI ID: 219850
• Journal Information: Solar Energy, Journal Name: Solar Energy Journal Issue: 2 Vol. 55; ISSN SRENA4; ISSN 0038-092X
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
99 GENERAL AND MISCELLANEOUS
AEROSOLS
ATMOSPHERES
DAYLIGHTING
ILLUMINANCE
MATHEMATICAL MODELS
SOLAR RADIATION
TURBIDITY