Reliability Assessments
Each year, NERC is responsible for independently assessing and reporting on the overall reliability, adequacy, and associated risks that could impact the upcoming summer and winter seasons as well as the long-term, 10-year period. As emerging risks and potential impacts to reliability are identified, special assessments are conducted that provide similar technical framework and insights about the range and specific aspects of these to guide steps that may be warranted. Unbiased judgment of industry’s plans for maintaining electric reliability in the future are founded on solid engineering through collaborative and consensus-based assessments.
By identifying and quantifying emerging reliability issues, NERC is able to provide risk-informed recommendations and support a learning environment for industry to pursue improved reliability performance. These recommendations, along with the associated technical analysis, provide the basis for actionable enhancements to resource and transmission planning methods, planning and operating guidelines, and NERC Reliability Standards.
The Reliability Assessment group develops the following key ERO reports, which fulfill the statutory requirements of Section 215 in the Energy Policy Act of 2005.
  • Long-Term Reliability Assessments annually assess the adequacy of the Bulk Electric System in the United States and Canada over a 10-year period. The reports project electricity supply and demand, evaluate transmission system adequacy, and discuss key issues and trends that could affect reliability.
  • Summer and Winter Assessments assess the adequacy of electricity supplies in the United States and Canada for the upcoming summer and winter peak demand periods.
  • Special Assessments are conducted on a regional, interregional, or interconnection-wide basis, as needed.
  • Methods and Assumptions documents (provided below) include the methods and assumptions used in the development of the various assessments. This information is modified only as frequently as the assessment areas change or enhance processes for assessing reliability.

Additionally, the Reliability Assessments program coordinates forecast reliability data between planning areas, the seven Regional Entities, and governmental organizations through the Electricity Supply & Demand Database.

For more information, please send any questions or comments to
NERC SRA 2021.pdf2021 Summer Assessment5/26/2021
NERC_LTRA_2020.pdf2020 Long Term Reliability Assessment12/15/2020
NERC_WRA_2020_2021.pdf2020/2021 Winter Assessment11/18/2020
Short_Circuit_whitepaper_Final_1_26_18.pdfShort-Circuit Modeling and System Strength Whitepaper2/1/2018
expand Header : Long-Term Reliability Assessments ‎(27)
expand Header : Methods and Assumptions ‎(5)
expand Header : Security-Related Assessments ‎(2)
expand Header : Short-Term Reliability Assessments ‎(1)
expand Header : Special Assessments ‎(16)
expand Header : Special Assessments on Environmental Regulations ‎(12)
expand Header : Summer Assessments ‎(18)
expand Header : Variable Generation Assessments ‎(11)
expand Header : Winter Assessments ‎(17)