Performance of anisotropic corrections for diffuse irradiance measured by the meo shadowring method applied for hourly and daily energetic time partitions.

Dal Pai, A. and Escobedo, J. F. and Dal Pai, E. (2013) Performance of anisotropic corrections for diffuse irradiance measured by the meo shadowring method applied for hourly and daily energetic time partitions. Energías Renovables y Medio Ambiente, 32 . pp. 45-51. ISSN 2684-0073

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Resumen

The objective of this paper is to apply and verify the performance of the anisotropic correction model developed for the MEO diffuse solar irradiance in the integrated values of the hourly and daily diffuse solar irradiations. Global, diffuse and direct irradiations from 1996 to 2005 were provided by the Laboratory of Solar Radiometry of Botucatu-UNESP. The anisotropic correction was developed for instantaneous values (5-minute-mean partition in W/m2) and applied to the integrated values on hourly and daily energetic time partitions. The validation was performed by the MBE and RMSE statistical indicators and slope of the correlation between the shadowring and reference diffuse irradiations. It was found that only the application of the geometrical correction was not sufficient to adjust the values of the MEO shadowring diffuse irradiations. The joint application of geometric correction and the anisotropic correction as a function of atmospheric transmissivity Kt significantly reduced the difference between the hourly and daily reference and shadowring diffuse irradiations, with a difference less than 0.8% between hourly values and less than 1.3% between daily values. The use of the geometric correction and the anisotropic correction significantly improves the precision of MEO shadowring method for measurement the diffuse solar radiation, representing a viable alternative for radiometric stations with limited financial resources that monitor hourly and daily diffuse radiation.

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