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This work presents a up-date of the solar radiation data for Madrid. All the available data has been collected and systematically written in a computer readable form. This allowed us to create a daily and an hourly data base, containing 34 and 17 years respectively. From these data a Reference Year has been defined. The validity of different correlations between global radiation and its diffuse fraction, models to convert from horizontal to tilted surfaces and the solar energy potential over some representatives fixed and tracking surfaces have been analyzed.
Macagnan et al. (1994) studied this question.