January 6, 2026
Bidirectional charging, whether it’s powering a home during an outage or feeding energy back to the grid, depends on a steady stream of trusted information to coordinate millions of mobile batteries safely and profitably. We need to know not only how much energy an EV can deliver, but also when, where, and under what conditions.
For every bidirectional charging session, the data foundation looks roughly the same: state of charge (SoC), plug status, rate of export, energy delivered, location, battery health, and driver preferences such as minimum SoC or next-trip timing. Together, these parameters tell an aggregator or utility how the vehicle can contribute without compromising mobility or safety.
That information can come from two main places, the charging equipment or the vehicle’s onboard telematics, and increasingly from both. Understanding how these data streams differ, and how they can work together, is becoming central to scaling vehicle-to-grid (V2G) and other bidirectional charging use cases.
Two Pathways to the Same Goal
Electric Vehicle Supply Equipment (EVSE) data, from networked chargers or inverter-based systems, has historically been the default source of energy measurement and session data in managed charging programs. Because it sits at the grid connection point, the charger can record start and stop times, power levels, and total energy flowing to the vehicle during charging and from the vehicle during discharge in bidirectional operation. For utilities, this looks familiar: it’s metered data tied to a physical device and certified under established standards such as IEEE 1547, with conformance tested through UL 1741, which together ensure safe, reliable bidirectional operation similar to other distributed energy resources like rooftop solar.
Certified bidirectional EVSE can measure both import and export energy as part of its inverter and protection functions, though not all devices are revenue-grade or expose these readings through open APIs. EVSE data provides the most direct link to the grid and remains the foundation for interconnection compliance and program settlement.
The EVSE alone offers only a partial picture; it records how much energy has flowed, but not the vehicle’s internal state or charging intentions. That deeper view comes through telematics data, transmitted securely via the car’s embedded connectivity or through approved third-party applications using OEM APIs. This information, including state of charge, temperature, charge limits, and driver preferences, enables precise bidirectional control, ensuring power is exported only when it won’t compromise driving range or battery health.
When combined, these data sources complement each other: the EVSE provides metered accuracy and grid compliance, while telematics, or an authorized data intermediary, supplies real-time operational intelligence. The charger records what happened; the vehicle reveals what’s possible next.
The Data Challenge for Bidirectional Charging
Bidirectional charging raises the bar on data quality. Unlike today’s managed charging programs, where approximate kWh is usually “good enough,” V2G requires accurate measurement of both import and export to support fair compensation and settlement. That’s where today’s data sources fall short.
New York’s Technical Standards Working Group (TSWG) recently commissioned a study, carried out by the Electric Power Research Institute (EPRI), that tested EVSE metering, vehicle telematics, and third-party data under controlled conditions. The goal wasn’t to set accuracy thresholds but to demonstrate how an accuracy testing methodology could work. The takeaway: all methods underreported energy relative to laboratory reference meters. Level 2 EVSE generally performed best, while telematics varied widely, especially when auxiliary loads were active. With only a small number of chargers and vehicles tested, the results aren’t statistically representative, but the signal is clear: neither EVSE nor telematics today provides revenue-grade data suitable for V2G settlement.
California offers a glimpse of what a solution looks like. In 2022, the CPUC adopted a Plug-in Electric Vehicle Submetering Protocol using NIST Handbook 44 accuracy standards, 1% in the lab, 2% in the field, and created a formal certification pathway for EVSE submeters. While these rules apply only to import (charging), not export, they demonstrate that states can set clear, achievable accuracy standards for EV charging equipment.
Another wrinkle: many aggregators apply their own correction factors (SOC conversions, loss adjustments), which help normalize customer experience but are not transparent and cannot stand in for utility metering accuracy requirements for customer billing and settlement.
The path forward is taking shape. For now, accuracy levels are sufficient for managed charging incentives, and programs should continue. But for V2G, regulators will need standards, just as California created for EVSE submetering, so that telematics and chargers can support fair, auditable settlement as the market matures.
Why Telematics Is Becoming Indispensable (But EVSE Isn’t Going Anywhere)
Telematics is clearly on the rise. The 2024 SEPA State of Managed Charging report highlights a rapid shift toward telematics integration as utilities look to scale active management across tens of thousands of vehicles, without rolling a truck to every driveway. The same logic applies to bidirectional charging: telematics is uniquely well-suited to capture the mobility context, where the vehicle is, when it’s plugged in, what the driver’s plans are, which determines when export is truly available.
Customer experience is where the tradeoffs show up most clearly. Program designers tend to treat the enrollment pathway as a first-order decision, not an afterthought. Telematics can lower participation costs because customers don’t have to buy an eligible charger or swap out hardware; they enroll through an OEM app and link their vehicle in a few clicks. But that story isn’t universal. Some drivers are wary of a third party “messing with” their car and are more comfortable with a dedicated EVSE pathway, something they can see on the wall, unplug if they choose, and mentally separate from the vehicle itself. It’s no accident that many of today’s leading programs are still built around EVSE-based incentives. In practice, we’re still in a hybrid phase where both EVSE and telematics pathways matter.
Telematics still brings a set of advantages that are hard to ignore. In residential V2G, the real value proposition is avoiding hardware constraints altogether. Drivers can enroll directly through their OEM app without needing a specific charger model or installing new equipment, significantly lowering friction for early V2G programs where enrollment ease can make or break pilot participation.
For fleets, telematics adds a layer of operational intelligence that EVSE alone can’t provide. Depot managers gain visibility into which vehicles are charged, which can safely export, and which ports are available, insights that flow through fleet software already connected to vehicle APIs. In this model, EVSE remains the primary tool for measuring energy flows, while telematics becomes the coordination and decision layer that enables real-time, fleet-wide dispatch.
Trust and control will ultimately decide how far telematics can go. When OEMs and aggregators manage the data link using tokenized consent (OAuth 2.0), drivers explicitly authorize participation and can revoke access at any time, an important privacy safeguard as millions of vehicles become grid assets. But the lesson from today’s programs is straightforward: there is no single “right” pathway. The most resilient V2G ecosystem will let customers choose the experience that feels right, EVSE-centric, telematics-centric, or a blend, while regulators and utilities work in parallel to bring both data streams up to the accuracy and transparency standards V2G will eventually require.
Barriers Still Standing
Even as the technology matures, telematics integration remains anything but plug-and-play.
Accuracy and standardization: Automakers use different data models, sampling intervals, and SoC definitions. Without harmonized protocols, aggregators must build one-off integrations for each brand. Standards like ISO 15118-20 and SAE J3072 point the way toward interoperability, but adoption will take time.
Data access and trust: Data access is quickly becoming a major competitive battleground. Vendors with direct, authorized API connections to automakers can offer stable, secure, and verifiable data, while others still rely on reverse-engineered links that can break when OEMs update security protocols. This creates real concerns around reliability and cybersecurity, but authorized integrations come with their own risk: they can lock in exclusive relationships between OEMs and a limited set of aggregators, narrowing interoperability and customer choice. As telematics becomes more central to V2G participation, regulators will need data-sharing frameworks that protect security without enabling market fragmentation or proprietary gatekeeping.
Regulatory alignment: Across jurisdictions, the rules for verifying and compensating energy data have not caught up with the realities of connected vehicles. As noted above in New York, the TSWG found that both EVSE and telematics data underreported energy use and lacked consistency across tests. Although EVSE and telematics cannot currently be counted on as alternative meters for billing purposes, they can continue to be used to support managed charging incentive calculations while solutions continue to improve. The finding highlights a broader regulatory gap: most states have no defined accuracy tiers or validation methods for telematics data, leaving utilities and aggregators without clear guidance on how to incorporate it into managed-charging or V2G programs. Establishing “fit-for-purpose” standards, stricter for billing, more flexible for incentives, will be essential to ensure consistency, fairness, and consumer protection as telematics-based programs scale.
Until that framework exists, program designers must balance innovation with prudence, using telematics for visibility and control, and EVSE for verification and compliance.
A Hybrid Future and the Policy Path Ahead
The most realistic near-term model for bidirectional charging is hybrid data orchestration, pairing EVSE metering with telematics intelligence. During a V2G session, the charger provides precise, certified measurements of power flow, while the vehicle contributes state of charge, battery limits, and driver preferences. This combination allows aggregators and utilities to both optimize dispatch and verify performance.
Over time, these data streams will converge. Standards like ISO 15118-20, SAE J3072, and UL 1741 SB are aligning how chargers and vehicles exchange energy and synchronization data, while open-API efforts led by CharIN and SEPA aim to make authorized data access simpler and more secure. As V2G-AC architectures mature under SAE J3072, onboard grid-interactive inverters will take on some measurement and control functions once confined to the charger. Still, the EVSE, or another certified grid-edge metering point, will remain essential for interconnection safety and verified energy accounting. For detailed coverage of standards and V2G interoperability, see the article Vehicle-to-Grid Interoperability: From Custom Integration to Common Infrastructure in Volume 1 | Issue 7 of V2G News.
Scaling this hybrid model will depend as much on data governance as on hardware readiness. Regulators can accelerate progress by:
- Establishing fit-for-purpose accuracy tiers that permit the use of telematics data for program verification while charting a path to revenue-grade certification.
- Advancing open, consent-based data-sharing frameworks, building on early discussions in New York and California around managed-charging and submetering protocols.
- Recognizing shared certification pathways for EVSE and onboard inverters under SAE J3072, IEEE 1547, and UL 1741 SB.
Federal and state agencies can further support progress through OEM utility data-access agreements that guarantee interoperability and protect customer privacy. Together, these steps would give utilities and aggregators the trusted, standardized data foundation needed for V2G to operate as a reliable grid resource.
The grid doesn’t just need more chargers; it needs trustworthy data links between vehicles, automakers, and utilities. Establishing that digital trust is what will make bidirectional charging a dependable, compensated grid resource, not just a promising idea.
Note: The author would like to thank Lauren Kastner, Director, Transportation Electrification at ICF Consulting, for her review and helpful comments on an earlier draft. Any remaining errors or omissions are the sole responsibility of the author.
