How Might EV Charging Impact the Bulk Power System? NERC Issues Findings and Solutions

Davis Wright Tremaine LLP

Davis Wright Tremaine LLP

NERC releases white paper on BPS reliability in different regions and makes grid-friendly recommendations for vehicle manufacturers and the electric industry

On February 8, 2024, the North American Electric Reliability Corporation ("NERC") published a white paper titled "Potential Bulk Power System Impact of Electric Vehicle Chargers."[1] The White Paper informs electric vehicle ("EV") stakeholders and policymakers about the need for greater cross-sector collaboration regarding the potential effects of the rapid growth of EV charging on Bulk Power System ("BPS") reliability.

The White Paper examines the impact of EV charging on the electric grid, discussing:

(1) electric charging traits and growth;

(2) industry preparedness; and

(3) NERC's own EV charger study, followed by an assessment of risks, potential solutions, and recommendations for further study.

Electric Charging Traits and Growth

With the automotive industry rapidly electrifying,[2] NERC recognizes that the increase in EVs and changes to their charging characteristics[3] will adversely impact the electric grid if not properly mitigated. For example, NERC addresses the special consideration required due to the impact of EV charging infrastructure on the load capacity requirements of the distribution and transmission systems.[4] The added load and strain on the electrical grid presented by EV charging will have different impacts depending on the scale of technology development, customer adoption, and the connection to the BPS.[5] NERC noted that EV charging falls into one of four classification levels[6] and that larger EV charging loads are anticipated to use higher charging levels that necessitate direct connection to the BPS due to a higher load capacity requirement.[7]

Furthermore, NERC notes that the ability of EV owners to charge at home and/or at public charging stations is an additional element of uncertainty in electric load forecasting for certain parts of the electric grid, potentially complicating BPS operations and planning.

Industry Preparedness

NERC has determined that there are significant knowledge gaps in how electric utilities and the EV charging community understand, plan, and model EV charging characteristics. In the White Paper, NERC identifies three critical areas of focus to address these gaps:

(1) modeling of EV charging behaviors;

(2) vehicle-to-grid programs; and

(3) transmission studies.

NERC points to the importance of adequate EV charging behavior modeling to help bridge the knowledge gap, stating that such modeling can be achieved through research, development, and iterative improvement.[8] NERC also recognizes that BPS operators have the need to integrate vehicle-to-grid programs and the impacts thereof into their operational planning assessments.[9] Lastly, NERC identifies the need for transmission planners to conduct robust studies to capture the impact EVs and their charging characteristics may have on common transmission planning initiatives.[10]

Study Findings and Recommendations

To further help address knowledge gaps about EVs and their charging characteristics, NERC undertook a study to determine how EV chargers interact with the electric grid and developed the following findings and recommendations:

Key Finding 1: EV chargers can negatively impact BPS reliability depending on the way they draw current from the BPS. Recommendation: EV and charging system manufacturers must increase their collaboration with electric utilities and establish performance criteria and standards regarding grid-friendly EV charging methods.

Key Finding 2: Reliability implications vary depending on the characteristics of the grid in specific locations and the number of EVs present. As a result, performance criteria are likely to vary based on location. Recommendation: Transmission planners will need to modify their planning criteria to indicate the types of charger performance criteria that are grid-friendly for their planning area. Different parts of North America will likely have different criteria, and it may be possible to address these criteria with EV charging software updates.

Key Finding 3: Knowledge gaps about EV charging behaviors create uncertainty in planning and understanding of the electrical impact that these devices may have on the BPS and associated policymaking. Recommendation: Vehicle manufacturers, the electric industry, and policymakers must increase collaboration to close knowledge gaps and address reliability concerns and benefits.


NERC's White Paper on the potential BPS impacts of EVs is a welcome addition to the industry's consideration of this important part of the energy transition. While it remains to be seen whether and to what extent NERC's recommendations are adopted by the industry, the recent moderation in EV sales and related consumer concerns with EV technology may provide ample additional time for NERC and other industry stakeholders to study more comprehensively the potential BPS impacts of EV charging technology, and take mitigating steps, before there is significant EV penetration on the nation's electric grid.

[1] See North American Electric Reliability Corporation, Potential Power System Impact of Electric Vehicle Chargers, January 2024 (the "White Paper").

[2] The Energy Information Administration has indicated that there will be significant EV growth through 2050. See White Paper at P 3.

[3] For the purposes of the White Paper, NERC defines charging characteristics as how and where the EVs will charge.

[4] White Paper at P 2.

[5] White Paper at P 3.

[6] The EV charging classification levels are: (a) Level 1 Chargers, which carry a range of 2.6 kW for a single-phase AC supply generally using a three-pin socket, which is the slowest of chargers available to end users; (b) Level 2 Chargers, which carry a range of 7.4 kW with a single-phase AC supply or 11 kW with a three-phase AC supply (maximum for at home); (c) Level 3 Chargers, which carry a range of 60–100 kW for "rapid" and up to 350 kW for "ultra-rapid" chargers and require a strong tie to the distribution substation or a connection for transmission service depending on the facility size and the total chargers in the location (e.g., public charging stations); and (d) Level 4 Chargers, which are at 1 MW or greater charging capacity and are planned for the trucking and other heavy equipment industries.

[7] White Paper at P 3.

[8] White Paper at P 5.

[View source.]

DISCLAIMER: Because of the generality of this update, the information provided herein may not be applicable in all situations and should not be acted upon without specific legal advice based on particular situations.

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