Assessing VGI in California: Techno-Economic Merit and Implementation Strategies
Project Update
The project team held a CEC kickoff meeting on November 18, 2025. In 2026, EPRI plans to hold a technical advisory committee meeting with key external stakeholders, conduct detailed analysis on approximately 100 distribution feeders from California IOUs to evaluate the technical merit, economic value, and also compare practical strategies to effectively realize the VGI benefits for California ratepayers. EPRI plans to work with the California IOUs to do a representative analysis.
The Issue
Vehicle-grid integration (VGI) implementation strategies are essential for meeting California’s climate and air quality goals, which rely in part on accelerating transportation electrification. Without VGI, industry stakeholders acknowledge that infrastructure upgrades alone cannot be deployed quickly enough to manage the charging peaks from the approximate 15 million electric vehicles (EVs) expected on California’s roads by 2035. Moreover, the costs of relying solely on conventional grid upgrades may be too high for California ratepayers to bear.
Project Innovation
Since VGI benefits are inherently location dependent, grounding the analysis and resulting insights based on actual distribution feeder data and detailed telematics and fleet data is the key strength of this project. The project intends to use a bottom‑up EV modeling approach built through the eRoadMAP platform, which incorporates geospatially and temporally detailed telematics, registration, OEM, and fleet data to represent vehicle behavior at a 0.25‑square‑mile resolution across California. This detailed model enables the team to capture when and where vehicles actually dwell at charging locations, allowing for an accurate assessment of VGI feasibility that would not be possible with a top‑down EV model. The project will also evaluate distribution‑level flexibility opportunities using real‑world California IOU feeders, analyzing approximately 100 feeders under scenarios that reflect load growth, DER penetration, and EV adoption using EPRI’s DRIVE distribution system modeling tool. In addition, the project will use the open‑source DER‑VET platform to assess VGI scenarios by simulating EV customer responses to different VGI mechanisms and evaluating the technical feasibility and economic value of participation in CAISO markets as part of value‑stacking strategies. Finally, by integrating inputs from eRoadMAP and DRIVE into DER‑VET, the project will establish a replicable analysis framework that other stakeholders can adapt even if they use different datasets or distribution system modeling tools.
Project Goals
Project Benefits
This project addresses key knowledge gaps that currently hinder the widespread deployment of VGI in California. VGI strategies are essential for meeting California’s climate and air quality goals, which rely in part on accelerating transportation electrification. Transportation electrification provides huge benefits in terms of emissions reductions compared to conventional ICE vehicles, but the magnitude of the distribution grid impact upgrades to support transportation electrification will be costlier to ratepayers without exploration of VGI. Without VGI, industry stakeholders acknowledge that infrastructure upgrades alone cannot be deployed quickly enough to manage the charging peaks from the approximate 15 million electric vehicles (EVs) expected on California’s roads by 2035. Moreover, the costs of relying solely on conventional grid upgrades may be costly for California ratepayers, based on the most recent rate case filings by the California IOUs.
Affordability
The project will evaluate the capability, opportunity, and operational consideration of VGI solutions, as a potential cost-effective alternative to traditional grid upgrades.
Reliability
The project will quantify the potential value of VGI solutions and provide insights into the extent to which EV flexibility can be effectively harnessed via various mechanisms (e.g., flexible service agreements, grid services, time-varying retail pricing), informing policy decisions and business strategies.
Key Project Members
Subrecipients
Match Partners
