Comparison of Solar Irradiance Models with Measurements for Two Regions in Southern and Northern Europe

This paper presents a comparative assessment of tilted irradiation models, using mean hourly measurements of total solar irradiation on a surface tilted 50 and 90 degrees and oriented south in Athens and Edinburgh respectively. Twelve sky-diffuse sub-models are used to estimate the global irradiation on the tilted surface from data on the horizontal plane. The best performing models seems to be MUNEER for both sites, but specifically PEREZ for Edinburgh and a combination of ISOTROPIC/PEREZ/REINDL for Athens.