Insolation Data Manual: Long-Term Monthly Averages of Solar Radiation, Temperature, Degree-Days, and Global Kt for 248 National Weather Service Stations

The number of individuals and businesses engaged in designing, installing and/or marketing solar energy conversion systems has been increasing rapidly in recent years. This trend has resulted in a growing need for solar radiation resource data for specific localities as well as for large geographic regions. The Insolation Data Manual presents monthly averaged data which describes the availabilityof solar radiation at 248 National Weather Service (NWS) stations, principally in the United States. Monthly and annual average daily insolation and temperature values have been computed from a base of 24-25 years of data, generally from 1952-1975, and listed for each location. Insolation values represent monthly average daily totals of global radiation on a horizontal surface and are depictedusing the three units of measurement: kJ/m2 per day, Btu/ft2 per day and langleys per day. Solar radiation data for 26 SOLMET stations are based on Standard Year Irradiance (SYI) corrected hourly measurements, while derived hourly estimations provide the basis for solar radiation values at the remaining 222 ERSATZ stations.