Climatological Solar Radiation Model

In 1995 the National Renewable Energy Laboratory (NREL) initiated the Data Grid Task under the U.S. Department of Energy Resource Assessment Program. The primary objective of the Data Grid Task is to estimate climatological averages of daily-total solar radiation at each point (cell) on a high-resolution (e.g., 40-km) uniform grid, using climatological parameters as input to a solar radiationmodel. This document describes the model, sources of input data, model products, and the initial evaluations of the model performance. The initial evaluations included comparisons of model output with 30-year averages derived from the U.S. National Solar Radiation Data Base and measured data for India, Saudia Arabia, Egypt, and Sudan. These comparisons indicate that the model is capable ofestimating monthly averages of daily-total solar radiation with an uncertainty of +/- 5%, when accurate input data are available. The results also indicate that available input data will yield results with an uncertainty of about +/- 10% for most locations around the world.