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Clearness-Based Sky Taxonomy and Predictions for Two Different Locations
D. Pavanello, W. Zaaiman, A. Colli, J. Heiser, S. Smith
Environmental Effect, PV System, Solar Radiation, Modelling / Modeling, Fuzzy Logic
Subtopic: PV System Reliability and Availability
Event: 28th European Photovoltaic Solar Energy Conference and Exhibition
Session: 5AO.9.5
3649 - 3655
ISBN: 3-936338-33-7
Paper DOI: 10.4229/28thEUPVSEC2013-5AO.9.5
0,00 EUR
Document(s): paper, presentation


This article presents a taxonomical analysis of the sky conditions, during 2012, for two different sites: the Joint Research Centre site in Ispra (Italy, European Solar Test Installation laboratories) and the site of Brookhaven National Laboratories in Upton (NY – USA). The key parameter is the sky clearness index kT, a dimensionless ratio of the global horizontal irradiance. In the first part, a taxonomical description using daily values of kT is presented, giving a general overview of the sky conditions during the year. In the second part the analysis is performed using short-term averages of the clearness index; remarkable properties of the statistical functions are highlighted and reinforced by using a fuzzy logic method, to extract time independent and site independent subsets. In the third part, a statistical analysis of the clouds intercepting the Sun’s trajectory is given, and finally, in the fourth part, some time-dependent correlations between the irradiance and other meteorological variables are studied.