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News Release: NREL Releases Updated Typical Meteorological Year Data Set

May 1, 2008

The U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) today released an updated typical meteorological year (TMY) data set derived from the 1991-2005 National Solar Radiation Data Base update. The TMY3 data and user’s manual are available at

The new data sets update and expand the TMY2 data sets released by NREL in 1994. The TMY3 data sets provide greater geographical coverage than previous TMY sets with information on 1,020 locations in the United States, project leader Steve Wilcox said. Only 239 locations were listed in the TMY2 data set.

A TMY data set contains typical meteorological values for specific locations. TMY data sets are widely used by building designers and others for modeling renewable energy conversion systems. Although not designed to show meteorological extremes, TMY data sets hold hourly values of solar radiation and meteorological elements for a one-year period that typify climate based on a much longer period of time.

Unless they are revised, computer programs designed for previous TMY data sets will not work with TMY3 data. NREL provides a software utility that allows reformatting of the TMY3 data to the TMY2 format at the TMY3 link above.

The TMY3 data sets and the users manual were produced by NREL's Electric and Systems Center under the Solar Resource Characterization Project, which is funded and monitored by DOE’s Energy Efficiency and Renewable Energy Office.

NREL is the U.S. Department of Energy's primary national laboratory for renewable energy and energy efficiency research and development. NREL is operated for DOE by Midwest Research Institute and Battelle.


—George Douglas