Global Irradiance: Typical Year and Year to Year Annual Variability

Models converting satellite images into the different radiation components become increasingly performing and give often better estimation of the solar irradiation availability than ground measurements if the station is not situated in the near vicinity of the application. Two different kinds of models are used to circumvent the lack of ground measurements: «average» models based on 10 to 20 years of ground measurements and interpolation between stations, and satellite based models that give «real» time series for specific years. The present study analyzes the interannual variability (variation from one year to the other) of the solar irradiation and compares it to the corresponding annual irradiation obtained from different evaluation models.