Book excerpt: Solar Resources takes stock of the resource - sunlight - on which any plan for solar heat conversion technologies must be based. It describes the evolution of theoretical models, algorithms, and equipment for measuring, analyzing, and predicting the quantity and composition of solar radiation, and it reviews and directs readers to insolation databases and other references that have been compiled since 1975. Following an overview of solar energy research by the editor, Raymond J. Bahm presents a comprehensive guide to available insolation databases and other information resources in the United States. Charles M. Randall and Richard Bird discuss the theoretical models and algorithms used to characterize the transference of solar radiation through the earth's atmosphere. Their chapter also addresses the important question of the accuracy of the data sets produced by the various modeling methods and algorithms. The National Weather Service (NWS) monitoring network and other major monitoring networks in the United States are discussed by Kirby Hanson and Thomas Stoffel. And Eugene Zerlaut covers the instrumentation used to measure total solar irradiance and spectral solar irradiance; he describes types of equipment, their manufacturers, procedures for calibration, and the accuracy of the data produced. Richard Bird and Carol Riordan explain the nature of spectral solar irradiance at the earth's surface, and John Jensenius describes the NWS Operational Solar Insolation Forecast System, which predicts the daily total global-horizontal insolation for two days. In the concluding chapter, Claude Robbins summarizes daylighting models and resources, and details methods for converting insolation date to illuminance data. Solar Resources is volume 2 in the series Solar Heat Technologies: Fundamentals and Applications, edited by Charles A. Bankston