This paper describes selected aspects of the METSTAT (Meteorological/Statistical) solar radiation model. METSTAT was developed specifically to support the production of the National Solar Radiation Data Base for the United States. The model was used to estimate hourly values of direct normal, diffuse horizontal, and global horizontal solar radiation for those times and locations for which measured data were not available. The input parameters for METSTAT include total and opaque cloud cover, aerosol optical depth, precipitable water vapor, ozone, surface albedo, snow depth, days-since-last-snowfall, atmospheric pressure and present weather. The model employs deterministic algorithms to generate acc;rate monthly means for each element for each hour and statistical algorithms to simulate the statistical and stochastic characteristics of multiyear solar radiation data sets.