On May 15, 2026, the North American Electric Reliability Corporation’s (NERC) Category 2 Inverter-Based Resource (IBR) Reliability Standards became effective. The new IBR standards are the result of directives issued in 2022 by the Federal Energy Regulatory Commission (FERC) to address the interconnection and reliability challenges caused by IBRs. In 2023, NERC in response began implementing a multi-phase plan to include Category 2 IBRs within the scope of its Reliability Standards, resulting in an aggressive outreach effort to register IBR generation for purposes of NERC compliance and leading to implementation of a first phase of mandatory Reliability Standards applicable to Category 2 IBRs.
What are IBRs?
IBRs are electronic power devices which are connected to the bulk power system (BPS) to convert direct current (DC) to the power grid’s alternating current (AC) electricity. IBRs include modern wind turbines, solar photovoltaic, and battery energy storage resources. In a 2023 report, NERC described IBRs as “the most significant driver of grid transformation today,” and noted the challenges the industry faces while integrating significant levels of IBRs due to differing technologies that are not immediately compatible with the power grid.
Category 2 IBRs are mid-scale generators, whereas larger Bulk Electric System (BES) Category 1 IBRs generate at higher capacity (75 MVA and above) and were already subject to NERC’s Reliability Standards. Category 2 IBRs are defined by NERC as generator operators (GOPs) or generator owners (GOs) of non-BES inverter-based resources which (1) either have or contribute to an aggregate nameplate capacity of greater than or equal to 20 MVA, and (2) are connected through a system designed primarily for delivering such capacity to a common point of connection at a voltage greater than or equal to 60kV. NERC created new registrations for GOs and GOPs (Category 1 and Category 2 for each respectively).
Why require Category 2 IBR participation in NERC Reliability Standards?
Following the 2022 directives, in 2023 FERC issued Order No. 901, instructing NERC to develop comprehensive IBR Reliability Standards as mid-sized IBRs in the aggregate can cause material disruptions on the BPS due to inverters suddenly tripping off and shutting down. Tripping is generally the result of inverter technology detecting a system condition outside of its safe operational limits. While Category 2 IBRs manage less voltage than Category 1, they are still utility-scale generators and tripping events in the aggregate can cause widespread reliability issues.
NERC’s Reliability Standards ensure that batteries and renewable generators with unique technologies remain reliable sources of energy in a time where energy demand is growing alongside the rapid development of large-load interconnections. Furthermore, the expansion of the Reliability Standards to include mid-size IBRs ensures that these generators support the power grid rather than cause instability due to unexpected inverter tripping.
What do the NERC Standards require of new IBR registrants?
Category 2 IBRs are now required to meet NERC compliance and Reliability Standards pursuant to the Compliance Monitoring and Enforcement Program (CMEP). The CMEP includes audits, self-certifications, self-reports, and enforcement actions and penalties. Furthermore, the following NERC Reliability Standards are effective to Category 2 IBRs without any modifications as of May 15, 2026:
- BAL-001-TRE: The Primary Frequency Response in the ERCOT Region
- IRO-010-5: Reliability Coordinator Data and Information Specification and Collection
- MOD-032-2: Data for Power System Modeling and Analysis
- PRC-012-2: Remedial Action Schemes
- PRC-017-1: Remedial Action Scheme Maintenance and Testing
- TOP-003-6.1: Transmission Operator and Balancing Authority Data and Information Specification and Collection
- VAR-001-5: Voltage and Reactive Control
- VAR-002-4.1: Generator Operation for Maintaining Network Voltage Schedules
The above-listed standards in general require Category 2 IBRs to provide information to Transmission Owners, Reliability Coordinators, and other entities, as well as maintain certain voltage control requirements. Note that further standards and standard revisions applicable to Category 2 IBRs are being considered and/or will become effective at a later date.
The May 15 effective date begins a new phase of regulatory monitoring and compliance for IBRs, and consultation with a professional can help applicable IBRs navigate the new requirements.
For more information, please contact Sean Neal and Lisa Gast.
Article By DWGP Summer Associate Juliette Gaggini – The George Washington University Law School, May 2027
