NREL NORTH AMERICAN SOLAR RADIATION ATLAS

This paper describes the online North American Solar Radiation Atlas, which displays solar collector performance at any location in the United States. The atlas is currently being developed at the National Renewable Energy Laboratory (NREL, Golden, CO). The new Atlas uses an interactive electronic map on the World Wide Web as an interface to multiple databases of solar collector performance and solar radiation data. The data delivered include estimated performance of various collector types such as tilted flat-plate surfaces, one- and two-axis tracking flat plate collectors, and concentrating collectors. The new World Wide Web user interface allows users to interact with maps of geographical features (terrain) and political features (state lines, county lines, cities, and roads) to select the location for which solar performance estimates are desired. Eventually, the Atlas will be a comprehensive electronic database of measured, modeled, and satellite-derived solar resource estimates, along with uncertainty statistics for the estimates at any location in the U.S. The principal data source for the first prototype version of the Atlas is the Climatological Solar Radiation (CSR) model, developed by NREL to estimate climatological averages of daily-total solar radiation at a 40 km spatial resolution (1). The model uses, as input, monthly climatological mean values of cloud cover, precipitable water vapor, aerosol optical depth, surface albedo, and total column ozone. These input parameters are available from various sources such as the National Aeronautics and Space Administration (NASA) and the National Climatic Data Center (NCDC). The model allows us to calculate the output for the various collector types such as tilted flat-plate surfaces, one- and two-axis tracking flat plate collectors, and concentrating collectors. A previous paper (2) described the revised model and the validation of the model results for four different solar collector orientations using ground-based measurements and models