U.S. Department of Energy

Solar Resource Assessment

DOE solar resource research focuses on understanding historical solar resource patterns and making future predictions, both of which are needed to support reliable power system operation. As solar technologies mature, more and increasingly larger solar energy systems are being installed across the country. Financing these systems requires assurance that they will produce the energy predicted through performance models. Failing to meet the minimum energy performance requirements can result in large financial penalties, requiring expensive risk mitigation measures. Accurate solar radiation data sets are the foundation of a successful performance model and are critical in reducing the expense associated with mitigating this performance risk.

Solar resource assessment provides the means to accurately determine the availability of solar radiation resources for developing, deploying, and operating cost-effective solar energy technologies per the SunShot goals. More information on solar resource assessment is available in the Solar Resource section of the High Penetration Solar Portal.

Within the SunShot Systems Integration activities, solar resource research and development (R&D) is being funded through DOE national laboratories and through competitive awards.

National Laboratory R&D

The National Renewable Energy Laboratory (NREL), with funding from DOE, is enabling the collection, analysis, and delivery of the accurate and sustainable solar resource information necessary to cost-effectively and reliably integrate high levels of solar electricity into the grid.


As solar energy systems become more prevalent, utility planners and grid system operators need to understand how high penetrations of systems that are dependent on a variable solar resource will impact the grid. Utility planners need to model the long-term performance and short-term variability of solar technologies and synchronize these models with the load and other variable generation sources, such as wind power. This requires solar radiation data at short time intervals, as well as a clear understanding of the spatial and temporal correlation of those measurements to determine the true impact of solar variability on the grid.

While accurate solar resource data are necessary for system planning, solar irradiance forecasts are also becoming critical for utility operators to cost-effectively plan for solar variability and ramping events. Providing an excessive amount of ancillary services for variability and ramping can be very expensive, and these costs will eventually be passed on to solar installations and their users. Providing operators with accurate forecasts will reduce overly conservative ancillary reserve requirements and thus reduce the cost of integrating solar into the grid. These forecasts may be necessary over a variety of temporal scales: 15 to 30 minutes, one to six hours, one day ahead, and potentially years ahead.

Therefore, the overall strategic goals for solar resource research at NREL are to:

  • Dramatically reduce the uncertainty of solar resource information used for component testing, power system design, financing, deployment, and operations
  • Deliver relevant and accurate solar resource information that is necessary to cost-effectively and reliably integrate high penetrations of solar technologies into the nation's electricity grid
  • Enhance capabilities to disseminate cutting-edge solar measurement technology and resource information to meet stakeholder needs in a timely and relevant fashion.

These issues are addressed in the solar resource assessment research activities at NREL, which encompass three key categories:

  • Solar resource informatics
  • Analysis, modeling, and forecasting
  • Partnerships and stakeholder engagement.

Success in each of these activities will be determined by increased confidence and reduced uncertainties in the solar radiation data used in performance and design models and other information products for R&D, decision making, system design, selection and operations, and solar portfolio decisions.


The specific objectives of NREL's solar resource research activities are to:

  • Improve the precision and accuracy of terrestrial solar resource measurements and model estimates from both ground and satellite-based observing platforms. This includes a national strategy to produce more refined solar and meteorological data at the appropriate temporal and spatial scales needed to advance renewable energy conversion technologies.
  • Enhance facilities to maintain and provide accredited radiometer calibrations and solar radiation measurements
  • Derive serially complete resource data sets from available solar and meteorological measurements and satellite observations of the atmosphere for wide use in engineering applications, such as solar energy conversion system performance and grid integration studies
  • Integrate the latest information technology concepts to provide easy access to cutting-edge solar measurement systems, resource information, industry standard models, and associated best practices for applying these data and models to a wide variety of projects
  • Create a comprehensive solar forecasting roadmap and conduct integrated R&D of advanced solar resource forecasting methods and predictive models on a national scale
  • Develop best practices, provide guidance, process feedback on solar resource assessment development needs, and collaborate with key government agencies undertaking synergistic R&D activities.

Competitive Awards

The following competitive solicitations represent recent and ongoing solar resource research efforts:

Learn about other DOE competitive awards for systems integration research that are in progress.