U.S. Data

NREL has provided solar resource data for the United States through the NRSDB for more than 25 years. We have also recently begun to collect data from a growing number of international locations, including India; to learn more, visit the NSRDB International page.

Available Versions

There have been substantial improvements in solar data collection and modeling technologies throughout the 25 years of existence of the NSRDB. As better technologies became available, NREL migrated to these new technologies and updated the NSRDB on an ongoing basis. NREL implemented major changes to the original database in 1991, 2005, and 2012.

These major changes have been referred to as "updates." In the most recent update, the NSRDB changed from using mainly empirical modeling and data collected at stations to using a physics-based modeling approach that provides solar radiation data for the entire United States in gridded segments (4 km x 4 km) using geostationary satellites.

With this shift to physics-based, gridded data collection, the version names were changed to distinguish them. The NSRDB updates that collected data from stations are now Meteorological Statistical Models (MTS) 1, 2, and 3. The most recent update that used the physics-based approach is now called the Physical Solar Model (PSM). Read more about the current version below.

Below is an overview of the NSRDB's versions. For detailed information about each, click on the links.

New Version Name

Prior Version Name

Temporal   Resolution

Spatial Resolution

Description

Physical Solar Model (PSM)

 

1998-2014 Update

1/2 hour

4 x 4 km

PSM uses a two-step process where cloud properties are retrieved using the adapted PATMOS-X model, which are then used as inputs to REST2 for clear sky and FARMS for cloudy sky radiation calculations. REST2 calculates both DNI and GHI. FARMS calculates GHI, and the DISC model is then used to calculate DNI. Aerosol properties are estimated using MODIS, MISR, and AERONET products. Water vapor is obtained from NASA MERRA. Additional meteorological parameters are also derived from MERRA.

Note: On March 21, 2016, the PSM version number changed from V2.0 to V2.0.1 because relative humidity and dew point data sets were corrected.

Meteorological Statistical Model 3 (MTS3)

1991-2010 Update

1 hour

1,454 stations

Solar data was obtained through the METSTAT (METeorological STATistical) model, and the meteorological data set was obtained from the National Climatic Data Center (NCDC) Integrated Surface Database (formerly Integrated Surface Hourly, ISH). http://www.nrel.gov/docs/fy12osti/54824.pdf

Meteorological Statistical Model 2 (MTS2)

1991-2005 Update

1 hour

1,454 stations

Solar data was obtained through the METSTAT and the State University of New York (SUNY) Empirical model (measured <1%) and the meteorological data set was obtained from the NCDC ISH database. http://www.nrel.gov/docs/fy07osti/41364.pdf

Meteorological Statistical Model 1 (MTS1)

(Original Version)

1961-1990

1 hour

239 stations

Solar data was obtained through METSTAT (modeled 93% and measured 7%), and the meteorological dataset was obtained from the NCDC for Surface Airways hourly data. http://rredc.nrel.gov/solar/pubs/NSRDB

About the Physical Solar Model

a test-image

The current version of the NSRDB (v2.0.0) was developed using the Physical Solar Model (PSM), and offers users the latest available data (1998–2014). NSRDB comprises 30-minute solar and meteorological data for approximately 2 million 0.038-degree latitude by 0.038-degree longitude surface pixels (nominally 4 km2). The area covered is bordered by longitudes 25° W on the east and 175° W on the west, and by latitudes -20° S on the south and 60° N on the north.

The PSM was developed by NREL in collaboration with the University of Wisconsin, the National Oceanic and Atmospheric Administration (NOAA), and Solar Consulting Services. PSM uses cloud properties from the satellite retrievals and then uses those properties to calculate surface radiation. The cloud properties in PSM are generated using the AVHRR Pathfinder Atmospheres-Extended (PATMOS-x) algorithms that have been adapted for use with GOES data. NREL developed the all-sky radiation model for solar applications (FARMS) that incorporates the cloud properties from PATMOS-x, aerosol optical depth (AOD), and precipitable water vapor (PWV) from ancillary sources to compute GHI in cloudy scenes. The DNI for cloudy scenes is then computed using the DISC model. The REST2 model is used to estimate DNI and GHI under clear sky conditions.  The meteorological data set associated with the NSRDB data was derived from NASA Modern Era-Retrospective Analysis (MERRA) datasets. MERRA has varying temporal and spatial resolution depending on the variable; however, the variables used in the NSRDB are hourly at 40 km2 spatial resolution, which is then interpolated to match the 4 km by 4 km grid and half-hourly temporal resolution.

Note: On March 21, 2016, the PSM version number changed from V2.0 to V2.0.1 because relative humidity and dew point data sets were corrected.

Descriptions of the variables included in the 4-km by 4-km NSRDB data are included in the tables below.

Data header (line1)

Element

Unit or Description

Source

NSRDB

Location ID

Site identifier

City

-

State

-

Country

-

Latitude

Decimal degree

Longitude

Decimal degree

Time Zone

Greenwich time zone, 0

Elevation

Meter

Local Time Zone

Hours from Greenwich, negative west

Data header (line2)

Element

Unit

Description

Clearsky DHI

Watt per square meter

- Modeled solar radiation on a horizontal surface received from the sky excluding the solar disk.
- This is assuming clear sky condition

Clearsky DNI

Watt per square meter

- Modeled solar radiation obtained from the direction of the sun.
- This is assuming clear sky condition

Clearsky GHI

Watt per square meter

- Modeled solar radiation on a horizontal surface received from the sky.
- This is assuming clear sky condition

Cloud Type

Unitless

Obtained from PATMOS-X 

Dew Point

Degree C

Calculated from specific humidity

DHI

Watt per square meter

Modeled solar radiation on a horizontal surface received from the sky excluding the solar disk.

DNI

Watt per square meter

Modeled solar radiation obtained from the direction of the sun.

GHI

Watt per square meter

Modeled solar radiation on a horizontal surface received from the sky.

Fill Flag

Unitless

'N/A': 0, 'Missing Image': 1, 'Low Irradiance': 2, 'Exceeds Clearsky': 3, 'Missing Cloud Properties': 4, 'Rayleigh Violation': 5

Snow Depth

Meters

Source: MERRA

Solar Zenith Angle

Degrees

Angle between the sun and the zenith

Temperature

Degree C

Source: MERRA

Pressure

Millibar

Source: MERRA

Relative Humidity

Percent

Calculated from specific humidity

Precipitable Water

Millimeter

Source: MERRA

Wind Direction

Degrees

Source: MERRA

Wind Speed

Meter per second

Source: MERRA

Data Availability

  • USA: 1998–2014
  • Other countries: 1998–2014, with 2005–2012 available publicly. To obtain the full 1998–2014 data set, please contactnsrdb@nrel.gov.
    • Anguilla, Antigua and Barbuda, Aruba, Bahamas, Barbados, Belize, Bermuda, Bolivia, Brazil, British Virgin Islands, Canada, Cape Verde, Cayman Island, Chile, Colombia, Costa Rica, Cuba, Curaçao, Dominica, Dominican Republic, Ecuador, El Salvador, Grenada, Guatemala, Guyana, Haiti, Honduras, Jamaica, Kiribati, Mexico, Montserrat, Nicaragua, Panama, Paraguay, Peru, Puerto Rico, Saint Barthélemy, Saint Lucia, Sint Maarten, St Vincent and the Grenadines, St-Martin, St. Kitts and Nevis, St. Pierre and Miquelon, Suriname, Trinidad and Tobago, Turks and Caicos Islands, U.S. Minor Outlying Islands, U.S. Virgin Islands, and Venezuela

Notes

  • Snow data has missing values.
  • 11/12/2015 – Relative Humidity data is incorrect; we are in the process of correcting the data.
  • 11/12/2015 – There is a time period in few pixels where the maximum DNI goes above the extraterrestrial values; we are in the process of correcting this.