A new method for correcting shadow band diffuse irradiance data.

Muneer, Tariq; Zhang, Xiaodong

Abstract

An instrument commonly used to measure diffuse irradiance is the polar-axis shadow band pyranometer. However, the shadow band that is used to prevent the beam energy from entering the pyranometer also obscures part of sky-diffuse irradiance. A correction factor must hence be applied to obtain as accurate as possible the estimation of the true diffuse irradiance. In this article, the development of a new model based on an anisotropic sky-diffuse distribution theory is presented. The proposed model is validated using two databases from different sites with various sky conditions. Drummond's method, which is based on geometrical calculation, is also examined using the same databases. Comparison of the results obtained through application of the proposed model, with those generated by Drummond's method shows that, for the case of Bracknell, UK the proposed method gives a root mean square error (RMSE) of 12 W/m2, as compared to Drummond's figure of 16 W/m2. For the case of Beer Sheva, Israel the proposed model produces an RMSE of 17 W/m2, while Drummond's procedure results in 23 W/m2. It has been demonstrated herein that the proposed method is not site specific.

Citation

Muneer, T., & Zhang, X. (2002). A new method for correcting shadow band diffuse irradiance data. Journal of Solar Energy Engineering, 124, 34-43. https://doi.org/10.1115/1.1435647

• Journal Article Type: Article
• Publication Date: Feb 1, 2002
• Deposit Date: May 27, 2008
• Print ISSN: 0199-6231
• Electronic ISSN: 1528-8986
• Publisher: American Society of Mechanical Engineers
• Peer Reviewed: Peer Reviewed
• Volume: 124
• Pages: 34-43
• DOI: https://doi.org/10.1115/1.1435647
• Keywords: Solar energy; Diffuse irradiance; Measurement; Shadow band Pyranometer; Anisotropic sky-diffusion theory; Case studies; Databases; Mathematical models; Comparison;; Drummond's geometric irradiance calculation; Anisotropic diffusion method; Accuracy evaluations
• Public URL: http://researchrepository.napier.ac.uk/id/eprint/1880
• Publisher URL: http://dx,doi.org/10.1115/1.1435647