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Improved accuracy models for hourly diffuse solar radiation.

Muneer, Tariq and Munawwar, Saima (2006) Improved accuracy models for hourly diffuse solar radiation. ASME Journal of Solar Energy Engineering, 128 (1). pp. 104-117. ISSN 0199 6231

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Abstract/Description

Solar energy applications require readily available, site-oriented, and long-term solar data. However, the frequent unavailability of diffuse irradiation, in contrast to its need, has led to the evolution of various regression models to predict it from the more commonly available data. Estimating the diffuse component from global radiation is one such technique. The present work focuses on improvement in the accuracy of the models for predicting horizontal diffuse irradiation using hourly solar radiation database from nine sites across the globe. The influence of sunshine fraction, cloud cover, and air mass on estimation of diffuse radiation is investigated. Inclusion of these along with hourly clearness index, leads to the development of a series of models for each site. Estimated values of hourly diffuse radiation are compared with measured values in terms of error statistics and indicators like, R2, mean bias deviation, root mean square deviation, skewness, and kurtosis. A new method called "the accuracy score system" is devised to assess the effect on accuracy with subsequent addition of each parameter and increase in complexity of equation. After an extensive evaluation procedure, extricate but adequate models are recommended as optimum for each of the nine sites. These models were found to be site dependent but the model types were fairly consistent for neighboring stations or locations with similar climates. Also, this study reveals a significant improvement from the conventional k-kt regression models to the presently proposed models.

Item Type: Article
Print ISSN: 0199 6231
Related URLs:
Uncontrolled Keywords: Solar radiation; Diffuse irradiance; Measurements; Predictions; Regression models; Site dependence; Atmospheric conditions; Statistical studies; Accuracy;
University Divisions/Research Centres: Faculty of Engineering, Computing and Creative Industries > School of Engineering and the Built Environment
Dewey Decimal Subjects: 500 Science > 510 Mathematics > 519 Probabilities & applied mathematics
600 Technology > 620 Engineering > 620 Engineering & allied operations
Library of Congress Subjects: T Technology > TK Electrical engineering. Electronics Nuclear engineering
Q Science > QA Mathematics
Item ID: 1879
Depositing User: RAE Import
Date Deposited: 14 May 2008 16:24
Last Modified: 26 Mar 2013 11:17
URI: http://researchrepository.napier.ac.uk/id/eprint/1879

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