VALIDATION OF THE MONTHLY MEAN HOURLY SOLAR IRRADIANCE HELIOS MODEL FROM VALENCIA (SPAIN) EXPERIMENTAL-DATA

Estimated irradiance values from the Helios model have been compared w ith experimental global irradiance values on four vertical planes meas ured in Valencia (Spain). The two versions of the model, based on the CEC and the Perez models for diffuse irradiance estimation, deviate to the same degree from the experimental values for the South and East p lanes. The version of Helios that uses the Perez model shows smaller d eviations than that based on the CEC model in the North plane, whilst the version based on the CEC model produces smaller deviations in the West plane.