An evaluation of illuminance measurements at Valladolid (Spain)

Data used in this study are obtained from a solar radiation station sited at the Low Atmospheric Research Center, CIBA, at Valladolid (Spain). Measurements from different sensors have been collected and put together in order to analyze different types of correlations. Results from two data sets, corresponding to years 2003 and 2004, are shown in this work. Data are firstly divided into eight categories according to the clearness of the sky. Then each category is analyzed independently in order to get conclusions about the parameter of interest, the solar illuminance. Here, an attempt to model hourly global horizontal illumination data is made; the year 2003 is used for calibration and 2004 for validation of the model.