The purpose of the Insolation Resource Assessment Program is to collect, standardize, certify, process,, and archive geophysical data for solar energy applications. The principal solar parameters to be measured are global, direct, diffuse and total radiation on an inclined surface. The measurement of the spectral distribution of solar radiation is also important to the development of several technologies. The aim of many of the completed, current, and planned projects presented in the IRAP Plan is to improve solar data collection methods and procedures and to refine solar radiation forecasting capabilities.