STOCHASTIC SIMULATION-MODEL OF HOURLY TOTAL SOLAR-RADIATION

A stochastic simulation model of hourly global solar radiation is presented in this paper. It is developed by introducing the concept of 'time dependent frequency distribution' (TDFD) of hourly insolation values. In this model the two most critical aspects of time series simulation, i. e. , the reproduced time series values which have the appropriate time dependent frequency distribution for the parameter being simulated and the correlation between successive values, are taken into account. The elimination of the TDFD of the data and the transformatioin of the data distribution to transformation Gaussian distribution (required for the stationary time series analysis) were carried out using a mapping technique. The autocorrelation function of the transformed data showed that the produced time series is stationary. Then, an antimapping coefficient matrix is developed, which provides a simple yet an effective simulation device. The described model has been applied in Athens (Greece) where hourly insolation data covering a period of two years are used. The theoretical results obtained using this simulation model, regarding both the TDFD and the correlation, are in agreement with the measured data.