UL 2594 4th Ed. Effective May 6, 2026: V2G Testing Mandatory for US DC Fast Chargers

UL Solutions has updated its safety standard for DC fast charging systems with the release of UL 2594, Fourth Edition, effective May 6, 2026. The revision introduces mandatory vehicle-to-grid (V2G) bidirectional energy interaction safety testing (Clause 8.12), directly impacting manufacturers, integrators, and suppliers of DC fast chargers targeting the U.S. market — particularly those seeking eligibility for federal and state clean transportation incentives such as the EPA Clean Bus Program and California Air Resources Board (CARB) subsidies.

Event Overview

On May 6, 2026, UL Solutions officially published UL 2594, Fourth Edition. This edition adds Clause 8.12, which specifies safety requirements and test procedures for V2G-capable DC fast charging equipment. The standard applies to all DC fast charging systems intended for sale or installation in the United States. Compliance is required for UL Listing; products failing V2G safety verification will not be granted UL certification.

Impact on Specific Industry Segments

DC Fast Charger Manufacturers

Manufacturers of DC fast charging hardware are directly affected because Clause 8.12 introduces new functional safety validation requirements tied to bidirectional power flow control, communication integrity, fault response timing, and grid-synchronization behavior. Impact manifests in product development timelines, certification costs, and design iteration cycles — especially for units previously certified under earlier editions without V2G functionality.

OEMs and EV Fleet Integrators

Original equipment manufacturers and fleet operators deploying or specifying V2G-enabled charging infrastructure must now verify that their selected chargers carry UL Listing under the 4th Edition. Absence of compliant certification may disqualify projects from EPA Clean Bus Program funding or CARB rebate applications, affecting procurement decisions and system architecture planning.

Charging Network Operators & Service Providers

Operators managing public or depot-based DC fast charging networks face operational implications: newly deployed units must meet the updated standard, and retrofits or upgrades involving V2G features require re-evaluation against Clause 8.12. This affects maintenance protocols, warranty terms, and interoperability assurance across heterogeneous charger fleets.

Testing Laboratories and Certification Bodies

Third-party labs authorized to conduct UL 2594 evaluations must implement updated test methodologies aligned with Clause 8.12, including V2G-specific fault injection, grid disturbance simulation, and ISO 15118-20 message validation. Capacity readiness, staff training, and equipment calibration for bidirectional energy testing become immediate priorities.

What Relevant Enterprises or Practitioners Should Focus On and How to Respond

Monitor official interpretations and implementation guidance from UL Solutions

UL Solutions may issue technical bulletins, FAQs, or transitional policies clarifying scope boundaries (e.g., whether legacy installations are exempt, or how “V2G-capable” is defined). Stakeholders should subscribe to UL’s regulatory alerts and review updates on ul.com/standards.

Prioritize verification of V2G-related hardware and software components in current designs

Manufacturers should audit firmware logic, isolation monitoring, contactor sequencing, and communication stack compliance with ISO 15118-20 and IEEE 2030.5 — as these underpin Clause 8.12 test execution. Early engagement with accredited labs for pre-assessment is advisable.

Distinguish between policy intent and enforceable compliance deadlines

While the standard takes effect May 6, 2026, enforcement timelines for specific programs (e.g., CARB’s rebate application windows or EPA’s fiscal year grant cycles) may differ. Enterprises should cross-reference program-specific eligibility rules rather than assume uniform cutoff dates.

Update internal documentation, supplier agreements, and procurement specifications

Procurement teams should revise RFQ templates and contractual clauses to explicitly reference UL 2594, Fourth Edition, and Clause 8.12. Suppliers must provide evidence of compliance — not just conformance statements — such as test reports from UL-authorized laboratories.

Editorial Perspective / Industry Observation

Observably, this update signals a formal institutional shift toward treating V2G not as an optional feature but as a safety-critical function requiring standardized validation. Analysis shows it reflects growing regulatory emphasis on grid stability and distributed energy resource integration — particularly in states with aggressive decarbonization targets. From an industry perspective, UL 2594 Ed. 4 is less a one-time compliance checkpoint and more an early marker of broader harmonization efforts likely to influence future versions of IEEE 1547, NEMA VE-1, and even international standards like IEC 62196-3. Current attention should focus less on whether V2G will be mandated and more on how quickly interoperable, certifiable implementations can scale across hardware platforms and utility interconnection processes.

Conclusively, UL 2594 Fourth Edition does not introduce new market access barriers per se, but it does raise the baseline for safety assurance in bidirectional DC fast charging. It is best understood not as a standalone regulatory event, but as a calibrated step in the ongoing alignment of EV infrastructure safety frameworks with evolving grid-edge functionality. For stakeholders, proactive technical alignment — rather than reactive certification — offers the most pragmatic path forward.

Source: UL Solutions official standard release notice (UL 2594, Fourth Edition, effective May 6, 2026); publicly available scope and clause details as published on ul.com/standards. Note: Implementation guidance, transitional provisions, and program-level enforcement timelines remain subject to ongoing clarification by UL Solutions and relevant incentive administrators (EPA, CARB) — these require continued monitoring.