The simplified Solis clear sky scheme was developed in 2008 to be used in automatic on-line satellite irradiance evaluation processes. It is a fast analytical broadband version of the spectral clear sky model Solis developed within the Heliosat project. Its weakness was the divergence for high aerosol optical depths (aod > 0.45). A new model was developed that can be applied for aod values up to 7, even if these values are not realistic. This ensures that the irradiance based on the model remains coherent whatever the quality of the input values. The paper presents a validation of the model on data acquired in Geneva, in four turbid sites, and in Durban and Stellenbosch, Sauran network sites.