December 16, 2025
Introductuction
As we wrap up 2025, two major reports offer some of the clearest signals yet about where vehicle-to-grid (V2G) is heading in the coming years. One comes from Massachusetts’ Electric Vehicle Infrastructure Coordinating Council (EVICC), which has evolved into one of the most thoughtful and data-driven state bodies planning for the EV–grid future. The other is a national market study focused on the round-trip efficiency (RTE) of bidirectional charging systems. This underexamined but crucial topic defines the technical and economic viability of bidirectional charging. Together, these reports illuminate both the policy readiness and the technology performance questions that will shape V2G’s trajectory over the next several years.
Massachusetts Steps Forward: EVICC’s Second Assessment
When Massachusetts created EVICC under the 2022 Climate Act, the original mandate was straightforward: build a roadmap for charging deployment and identify barriers to meeting the Commonwealth’s electrification goals. Two years later, the Council’s work has matured into something deeper. EVICC is no longer simply mapping where chargers must go; it is assessing how charging interacts with the grid, how managed charging can reduce system costs, and how bidirectional technologies fit into long-term strategies for resilience and affordability.
The Second Assessment reflects this evolution. Modeling from Synapse Energy Economics, Resource Systems Group (RSG), and the Center for Sustainable Energy (CSE) shows that the state is thinking in integrated terms, asking not just how many chargers Massachusetts needs, but how they should behave and how EV loads should be shaped so that infrastructure upgrades are targeted, not reactive. This perspective puts vehicle-grid integration (VGI) at the center of the electrification strategy, rather than treating it as an add-on.
One of the most notable developments is the Assessment’s treatment of V2X. Instead of describing bidirectional charging as an emerging curiosity, EVICC frames it as a practical set of tools with near-term applications. V2G is identified as a means to help shave peaks and support demand response; V2H and V2B provide resilience benefits during outages; and school bus V2G stands out as the most immediately scalable use case because of its predictable duty cycles and concentrated charging at depots. The Council is appropriately measured about light-duty V2X, but it clearly anticipates growth and acknowledges the need for demonstrations, standards, and alignment across state and utility programs.
That alignment is already taking shape. The Assessment highlights Massachusetts Clean Energy Center’s (MassCEC’s) $6 million V2X Demonstration Program, which V2G News covered in Volume 1 | Issue 6. The project will deploy roughly 100 bidirectional chargers in residential, commercial, and school applications. Installations should be complete in early 2026, and data collection will extend throughout the year. This multi-use-case, real-world testbed will be one of the most important V2G learning opportunities in the nation. Early results have already revealed familiar national challenges: terminology inconsistencies, rapidly shifting OEM capabilities, and uneven commercialization in the charger market. But these are exactly the kinds of issues a demonstration program should surface and address.
Across the Assessment, EVICC consistently returns to a central theme: managed charging is the essential precursor to V2G. Whether achieved through time-varying rates, utility-directed charging, or strong customer signals, managed charging establishes the behavioral and technical foundation on which V2G can eventually scale. Massachusetts is building this foundation thoughtfully, supported by the Interagency Rates Working Group, evolving utility proposals, and a growing understanding of how load flexibility will shape future distribution system planning.
What makes EVICC nationally significant is not simply what it says, but how it approaches the work: methodically, transparently, and with a long-term view grounded in practical realism. The Commonwealth isn’t betting on a sudden surge in bidirectional charging adoption; it is preparing its institutions, programs, and infrastructure for the moment when standards, products, and customer offerings align. That is the kind of disciplined planning that will enable bidirectional charging to scale responsibly in the second half of this decade.
A National Look at Performance: The V2X Round-Trip Efficiency Study
V2X Round-Trip Efficiency Market Study: Final Report, ET25SWE0028 (December 2025)
While the EVICC assessment shows how a state is preparing for bidirectional charging, the V2X Round-Trip Efficiency Market Study tackles a very different challenge: understanding how efficiently energy moves through bidirectional systems. This is not academic. Round-trip efficiency (RTE) determines how much energy is lost during a charge–discharge cycle and therefore affects customer economics, program design, avoided cost modeling, and grid-level forecasting. It is surprising how little consensus the industry has had on this topic until now.
The study begins by highlighting an uncomfortable reality: unlike stationary storage, V2X systems have no standardized method for measuring or reporting efficiency. Manufacturers use different measurement boundaries, different testing conditions, and different assumptions. Some report AC-to-battery charging efficiency; others report DC-to-AC discharge efficiency; few specify temperature or duty cycle. Without common conventions, it is nearly impossible to compare products or value streams.
To address this, the research team combined an extensive literature review, a catalog of V2X-capable EVs and chargers, and structured interviews across OEMs, utilities, standards bodies, aggregators, and software firms. The result is the clearest synthesis yet of how energy flows, and is lost, across V2X systems.
One of the study’s most important findings is that real-world V2G efficiency is significantly lower than many program models assume. While planners often use an 80–85 percent RTE assumption, empirical studies put AC-AC V2G efficiency between 53 and 62 percent. This gap has substantial implications. If efficiency losses are understated, customer-facing revenue projections become inflated, and utilities risk underestimating the net load impacts of large-scale V2G deployment.
The study also isolates the two parameters that most strongly affect efficiency: power level and ambient temperature. Low-power operation magnifies fixed conversion losses, while high-power operation improves efficiency until thermal limits interfere. Temperature, meanwhile, affects both the battery and the inverter, meaning an EV operating outdoors in winter or summer may perform quite differently than lab tests suggest. Other parameters, state of charge, depth of discharge, and battery chemistry, play roles but have comparatively less influence on operational efficiency.
One challenge highlighted in the report is the underappreciated impact of standby consumption. A typical residential EVSE may consume roughly 219 kWh per year solely in standby mode. Commercial chargers consume more. These losses accumulate across fleets and become non-trivial. The study points to sleep-state controls as a promising solution, though more validation work remains.
The report also offers encouraging evidence that efficiency-aware smart charging algorithms can meaningfully reduce losses. Some strategies tested in simulated fleet and frequency-regulation scenarios demonstrated measurable reductions in energy waste. These are early but important signals of how software and optimization could complement hardware improvements in raising overall system performance.
The one short list worth preserving here summarizes the three V2X applications that consistently emerged as the most commercially mature across interviews and case evaluations:
- Resilience during outages
- Behind-the-meter peak shaving
- Load shifting aligned with lower-cost or lower-emission periods
These use cases depend on targeted events rather than continuous cycling, helping balance value with battery health and efficiency constraints.
Where These Reports Point the Industry Next
Viewed together, the EVICC Assessment and the round-trip efficiency study tell a coherent story about where V2G stands today. Policy institutions are becoming more sophisticated in their understanding of V2X, integrating it into long-term planning frameworks and establishing demonstration programs that will shape future rules and incentives. At the same time, the technical community is beginning to build the standardized methodologies and performance metrics necessary for V2G to function as a trusted, compensable grid asset.
The implications are clear. States must continue building the programmatic and regulatory foundations that will eventually support V2G participation. OEMs and charger manufacturers will need to prepare for greater transparency around performance, efficiency, and interoperability. Utilities will require accurate RTE data to design tariffs, evaluate cost-effectiveness, and forecast system impacts. And aggregators must refine their models to reflect real-world, not theoretical, performance.
Perhaps most importantly, both reports underscore that the move from pilots to scale will require a shift from aspirational framing to empirical grounding. Managed charging will remain the critical on-ramp. Standards will play an increasingly central role. Demonstrations like those in Massachusetts will generate the operational data needed to inform rulemaking. And efficiency characterization, once a niche topic, will become a defining metric of market credibility.
If 2025 was the year V2G reentered the national conversation, 2026 will be the year the industry begins tying that conversation to real data, real programs, and real customer value. These two reports offer a roadmap for what comes next, and a reminder that responsible scaling depends on both policy readiness and technical rigor.
