Ten to thirty years of ground data acquired at 25 different sites are used to analyze the year to year variability of the solar global irradiation and to compare it to average and/or interpolated data, software generated typical years and satellite derived data. The main conclusions are that the majority of the average and typical years give values within the interannual variability, and that even with a low bias, the «real» years evaluated from satellite images follow in a satisfactorily manner the interannual variablility.