National Solar Radiation Data Base
Using data collected from 1961 through 1990, the National Solar
Radiation Data Base will replace the SOLMET/ERSATZ dats base derived
from data collected from 1952 through 1975. The new data base will
more accurately portray the solar resource for the following reasons:
The 30-year period of data collection is long enough to establish
averages and extremes of solar radiation paramaters, and it coincides
with the same 30-year period used for the National Oceanic and Atmospheric
Administration's latest update of climate statistics.
More measured data were available during 1961 through 1990. For
the SOLMET/ERSATZ data base, there was only one measured parameter;
global horizontal solar radiation at 26 sites. The new data base has
measured data for up to 55 of the 250 sites. For a majority of these
55 sites, two parameters were measured: global horizontal solar radiation
and direct beam solar radiation. Diffuse solar radiation was also
measured for several years at nine sites.
Better models estimate solar radiation at sites and times where no
measurements are available. A meteorological statistical model provides
better estimates of solar radiation for sites and times where no
measurements are available.
The certainty of the measured data is better. A radiometer calibration
facility, set up by the National Oceanic and Atmospheric Administration
in Boulder, Colorado, performed routine calibrations to ensure the
accuracy of instruments used to measure solar radiation.
Quality assessment procedures flag solar radiation data to show the
source of the data (measured or modeled) and the uncertainty. Unlike the
SOLMET/ERSATZ data, this permits the user to assess the uncertainty of the
Return to RReDC Homepage ( http://www.nrel.gov/rredc )