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Insight from a Detailed Comparison between the Solar Irradiance Measured in the North of France, and Its Satellite-Based and Simulation-Based Estimates
N. Ferlay, G. Chesnoiu, P. Dubuisson, F. Auriol, G. Brogniez, F. Parol, T. Elias, M. Compiègne, D. Ramon
PV Systems and Storage – Modelling, Design, Operation and Performance
Subtopic: Solar Resource and Forecasting
Event: 36th European Photovoltaic Solar Energy Conference and Exhibition
Session: 5CV.3.9
ISBN: 3-936338-60-4
0,00 EUR
Document(s): poster


An advanced analysis of PV cells performance should ideally come with a detailed knowledge of the solar radiation’s characteristics. Very important is of course the density of flux on the surface considered. But PV cells are also and differently sensitive to different radiation’s properties, e.g. the angular distribution of the downwelling radiation, its spectral content, the partition between its direct and diffuse components, or more subtly the solar circumsolar contribution. These properties of the radiation field vary with the meteorology state of the atmosphere, and very much when (broken) clouds are present. Being aware of the multiple aspects of this dependence is important. Also important, for different applications, is the ability to simulate correctly or not the cloud/radiation interaction, in order to provide accurately or not the solar irradiance from satellitebased measurements. To tackle and highlight these questions, we present here different characteristics of the solar irradiance as measured at a given site (North of France), their relation with the cloud covers, and the main differences between the solar ressource measured in situ, as routinely provided by satellite-based products (CMSAF), and as simulated by models assimilating the atmospheric state of the atmosphere. We show and attempt to explain the significative biases that exist concerning the estimate of the direct and diffuse radiation components, biases that often compensate to give quite accurate total irradiance. We show also that 3D radiative transfer effects can be commonly significative, and how they degrade the performance of satellite-based or simulation-based solar irradiance estimates.