Figure 11: Frequency distributions of the clearness index for Carpentras (France, 2001). For locations with higher yearly global irradiation, the second peak (clear sky) of the distribution grows. With the new method, the RMSE between measurement and synthesis can be reduced significantly (RMSE = 801 and 962 counts for Aguiar and Skartveit and RMSE = 248 counts for new method).