A method to generate synthetic hourly solar radiation globally

This paper develops a stochastic procedure for generating synthetic sets of hourly solar irradiation values, suitable for use in solar simulation design work. The daily atmospheric transmittance K_t for the day in question is broken down into hourly irradiation events by a stochastic disaggregation procedure. The necessary disaggregation models were constructed using the quasi-universal hourly atmospheric transmittance k_t, instead of the irradiation itself, as the random variable. Analyses of meteorological records revealed that both the marginal probability and stochastic features of sets of hourly events k_t within an individual day can be closely predicted using the K_t for the day. Results indicated that the parameters defining the disaggregation procedure were independent of geographical location. The values of k_t are found to be closely modeled by a Beta distribution, and a mean correlation coefficient between successive hourly values of k_t was found to be 0.54±0.14. An algorithm is described from which unlimited hourly solar irradiation data may, therefore, be generated using only the 12 monthly means of daily events, K_t.