October 21, 2025

Vehicle-to-grid (V2G) technology offers a compelling vision: electric vehicles that don’t just consume electricity but also support the grid with stored energy and fast, controllable power flow based on real-time grid conditions. That vision is already visible in pilots and early deployments. But achieving scale beyond custom integrations hinges on one thing above all: interoperability: equipment and software that actually work together across brands, sites, and operators in the wild.

What Interoperability Means

Interoperability means any compliant [1] EV can plug into any compliant charger and deliver the same services (e.g., grid services or vehicle-to-building functions) regardless of brand, site, or operator. Today, that’s not the norm. An electric school bus that exports power at one depot may not work when connected to a different vendor’s bidirectional charger at another site. Likewise, an electric pickup truck that provides emergency backup power at the owner’s home may not work with a neighbor’s system from another manufacturer. These gaps aren’t just inconvenient; they raise integration costs and make it hard for utilities and fleet operators to count on V2G capacity at scale.

A core reason is the continued use of proprietary protocols or vendor-specific variations inside otherwise open standards. Open standards create the common rulebook, but true compatibility only emerges when they’re implemented consistently. In practice, interoperability is achieved when vendors build their products to open standards and demonstrate, through certification and multi-vendor testing, that these products operate together effectively in the field.

Why Proprietary Solutions Persist (and Their Limits)

There’s a genuine business tension in how interoperability evolves. Proprietary integrations can be quicker to launch and give vendors tighter control over features and customer experience. When you control both the vehicle firmware and the charging station software, you can optimize performance and deploy new features rapidly without coordinating with competitors. That speed advantage can win early pilot programs and create switching costs that feel like a competitive moat.

But this approach has structural limits that emerge at scale. Every new vehicle-charger pairing requires custom engineering and testing, support costs multiply with each unique combination, and customers face equipment that only works within a single vendor’s ecosystem, thereby limiting flexibility and depressing asset values.

Open, standards-based implementations require more up-front discipline, such as vendors must agree on feature sets, coordinate security protocols, and align on certification processes, which makes V2G more affordable. But once a vendor builds to certified open standards, that investment unlocks access to any compliant vehicle or charger. Utilities and fleet operators can issue procurement requirements that multiple vendors can meet, increasing competition and driving down prices.

When basic interoperability becomes table stakes, vendors differentiate on what actually matters: reliability, analytics, service quality, and total cost of ownership. A pragmatic path forward is emerging: build the core V2G functionality to open standards and certify it, then layer differentiated capabilities on top without breaking baseline compatibility.

That’s why coordination across industry groups and policies that reward certified, open implementations matter for getting from pilots to true plug-and-play.

From Standards to Real Interoperability

Standards are the prerequisite but not the same thing as interoperability. They define how systems should communicate and operate safely. But most standards leave room for interpretation and optional features; that flexibility is great for innovation, but terrible for consistency. Two devices can both be “standards-compliant” on paper and still fail to work together in practice.

To make products from different vendors behave the same way, the industry uses interoperability profiles, narrower implementation guides that sit on top of broad standards. An interoperability profile removes ambiguity for a given scenario by selecting required features, spelling out security and authentication details, and linking to specific tests that products must pass. In short, interoperability profiles turn broad standards into precise, certifiable implementations that vendors can build once and buyers can reference in procurement to get reliable, compatible solutions.

In the sections that follow, we’ll examine how this interoperability profile-based approach applies to each technical layer in the North American V2G ecosystem, from the plug-level connection between vehicle and charger, to grid safety requirements, to the back-office systems that manage everything.

The Technical Stack: Three Critical Layers

Layer 1: Vehicle ↔ Charger Communication

This is the conversation that happens at the plug, or how the EV and charging equipment recognize each other, authenticate securely, and coordinate power flow.

The standard: ISO 15118-20 defines the messages for “Plug-and-Charge” (automatic authentication) and bidirectional power transfer over both AC and DC charging. It works with both the CCS1 connector standard and the newer SAE J3400 connector (also known as NACS, the North American Charging Standard), though adoption for bidirectional charging on J3400 is still emerging.

For V2G systems with on-board grid-interactive inverters (V2G-AC), ISO 15118-20 provides a suitable framework in regions such as the EU, where local grid codes align with its current specifications. However, in North America and other jurisdictions that rely on IEEE-based interconnection requirements, the standard does not yet ensure compliance. An amendment to ISO 15118-20, which is currently under development, is expected to close this gap by standardizing V2G-AC functionality for these regions.

What’s needed for interoperability: Consistent implementation of ISO 15118-20 across all vendors, plus a robust Public Key Infrastructure (PKI), which is essentially a secure certificate system that handles authentication, similar to how your browser verifies secure websites. The CharIN organization runs “Testival” events where vendors bring their equipment to prove it works with competitors’ products, helping resolve ambiguities before they cause field failures.

The connector standard defines the physical plug; ISO 15118-20 plus PKI provide the secure session that V2G requires.

Layer 2: Grid Interconnection and Safety

Once power flows in both directions, the system functions as a distributed energy resource (DER), similar to rooftop solar or stationary storage, and must comply with established grid safety and performance requirements. The discussion that follows focuses on jurisdictions using the IEEE 1547 interconnection standard, primarily in North America. Regions that follow IEC-based standards, including the EU, apply different grid codes and certification pathways for V2G interconnection..

The standards: IEEE 1547 and 1547.1 specify safety requirements for any DER connecting to the grid. These include rules for disconnecting during grid faults, responding to voltage and frequency changes, and providing required telemetry. To implement these requirements, devices must support at least one of these three communication protocols: IEEE 2030.5, DNP3 (IEEE 1815), or SunSpec Modbus.

How it works: Utilities often publish required parameter sets (sometimes called Utility-Required Settings) that translate grid-code rules into concrete values, for example, “disconnect within 0.16 seconds if voltage exceeds X” or “reduce power output when frequency rises above Y.” These settings are delivered to the equipment digitally and can be updated as programs evolve.

For V2G-DC systems using a bidirectional DC charger, the bidirectional inverter (the component that converts between DC and AC power) lives inside the charging station. This means the system can be certified and controlled just like solar or battery storage: the pathway is well-established. However, for V2G-AC systems, the inverter capabilities are inside the vehicle, not directly accessible to utilities. Additional standards work is underway to define how the vehicle communicates required inverter data and control functions through the charger or cloud systems to ensure full interoperability and certification.

Layer 3: Back-Office and Market Signals

The top layer handles network management, billing, demand response programs, and coordination with grid operators. Interoperability at this level is achieved through standardized data exchange protocols and open interfaces that enable seamless communication between utility systems, aggregators, and charging networks.

Key protocols:

• OCPP (Open Charge Point Protocol): Manages communication between chargers and network operators. Version 2.0.1 is widely deployed in Europe. The forthcoming 2.1 version better aligns with U.S. utility requirements and IEEE 1547 certification needs, but adoption remains limited.
• IEEE 2030.5: Can also operate at this layer, providing a more integrated path for utilities to manage charging equipment alongside other DERs.
• OpenADR (Open Automated Demand Response): Is focused on managing demand response (or managed charging) programs rather than interconnected DERs.
• OCPI (Open Charge Point Interface): Maintained by the EVRoaming Foundation, enables roaming and cross-network portability—allowing EV drivers to use chargers from different network operators seamlessly.

Who’s Building the Ecosystem

Interoperability is being solved across multiple layers of the EV-grid stack, and no single organization owns the whole system. That diversity is healthy, so long as the pieces align.

The following organizations play key roles in advancing V2G interoperability:

• IEEE, SAE International, UL, and ISO/IEC – Develop the foundational standards that govern grid codes, safety, and communication protocols. (For example, OCPP is being adopted as an IEC standard. SAE also leads development of J3072 and contributes to ISO 15118-20 Amendment 1 to define requirements for V2G-AC functionality.)
• CharIN – Publishes ISO 15118-20 guidance, including bidirectional power transfer specifications, and hosts multi-vendor “Testival” events to validate real-world interoperability.
• SunSpec Alliance – Maintains CSIP and IEEE 2030.5 J3072 profiles that enable grid-code–compliant DER control and the SunSpec Modbus protocol.
• OpenADR Alliance – Develops open communication protocols for automated demand response programs.
• Smart Electric Power Association (SEPA) and NIST – Translate technical specifications into practical, buyer-ready profiles that can guide procurement and certification.
• IEA HEV Task 53 – Advances global testing methods and best practices for CCS-based V2G systems.
• EVRoaming Foundation – Ensures cross-network roaming and data portability for EV charging infrastructure.
• California Energy Commission (CEC) – Through its Chargeyard initiative, it funds and coordinates projects to validate V2G interoperability in real deployments.
• Open Charge Alliance, EVCan, EPRI’s Vehicle PowerLink (VPL), and the CEC’s V2G Equipment List – Provide reference tools and certification databases that confirm which products meet interoperability standards.

The Path to Plug-and-Play V2G

We don’t need universal interoperability to deliver value today. V2G will continue through proprietary and bilateral integrations, especially in controlled settings—single-operator sites where vehicles, chargers, and network systems are all known and managed. Those deployments aren’t a detour; they’re the proving ground that yields the data to refine profiles, tighten certification, and strengthen security.

To move from custom projects to true plug-and-play, policy and procurement need to pull in the same direction:

1. Funding and incentives: Tie public funding and program eligibility to open-standards profiles and certified implementations. Make interoperability a requirement, not an option.
2. Procurement language: Write compatibility requirements into utility and fleet procurements. Specify that equipment must be certified to recognized interoperability profiles.
3. Grid interconnection: Align requirements with IEEE 1547/1547.1 and companion certifications so V2G equipment follows the same proven pathway as solar and storage.
4. Testing infrastructure: Support neutral testbeds where vendors can validate compatibility. Publish conformance and interoperability test results so buyers can make informed decisions.
5. Security foundation: Establish clear PKI governance so Plug-and-Charge authentication works reliably across vendors and networks.

Do this while deployments continue, and V2G shifts from custom integration to common infrastructure, leading to lower costs, higher confidence, and real scale. The technology is ready. The standards are maturing. What’s needed now is coordination: aligning incentives, procurement, and certification to reward the open, testable implementations that will make V2G work for everyone.

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Note: The author would like to thank James Mater of QualityLogic and Matt Zebiak of 2050 Partners for their review and comments on an earlier draft of this article. Any remaining errors or omissions are the sole responsibility of the author.

[1] Compliant refers to adherence to the relevant open standards governing interoperability for both unidirectional and bidirectional charging.

For more information on V2G standards and interoperability, visit:

• QualityLogic, Webinar: Getting to EV Charging and V2G Interoperability. 
• Interstate Renewable Energy Council, Paving the Way: Vehicle-to-Grid (V2G) Standards for Electric Vehicles. 

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