January 6, 2026
Tayarani, H., Rabinowitz, A., Jenn, A., & Tal, G. (2025). Assessment of vehicle-grid integration profitability subject to real-world driver behavior and electricity tariff. Energy, 341, 139302. https://doi.org/10.1016/j.energy.2025.139302.
As bidirectional charging moves from demonstrations toward early commercialization, the industry continues to grapple with a fundamental question: under real-world conditions, does vehicle-to-grid participation deliver enough value to justify the added complexity, cost, and perceived risk? A new peer-reviewed study from researchers at the University of California, Davis offers one of the most grounded answers to date by examining V2G not in theory, but as it would operate in the lives of actual drivers, under today’s electricity tariffs, and with battery degradation fully accounted for.
Published in a peer-reviewed journal at the end of 2025, the study arrives at a pivotal moment for the industry. Rather than asking whether bidirectional charging can work in principle, the authors focus on when it creates durable, repeatable value under everyday conditions, and when it does not. In doing so, the analysis helps explain both why V2G has struggled to scale uniformly to date and where it is most likely to succeed as commercialization begins.
Purpose of the Study: Stress-Testing V2G Against Reality
The central purpose of the study is to assess the economic and environmental value of vehicle-grid integration, particularly bidirectional charging, once real-world constraints are applied. The authors are explicit that prior V2G analyses have often overstated value by relying on idealized assumptions about driving behavior, plug-in availability, electricity prices, or battery wear. This study deliberately strips those assumptions away, grounding its analysis in observed driver behavior, realistic parking durations, actual charging power levels, and empirically derived battery degradation costs.
At its core, the study is about usable flexibility: how much grid-supportive capacity real vehicles can provide, when that capacity is actually available, and what factors constrain its value in practice. For V2G specifically, the authors seek to understand how often vehicles are parked, and plugged in, long enough to support bidirectional operation without compromising driver mobility; how sensitive V2G value is to charging power, particularly within the Level-2 power range (6.6 kW – 19 kW) most relevant for near-term deployment; how much of the gross revenue from bidirectional charging is offset once battery degradation is treated as a real economic cost rather than an abstract concern; and how strongly retail electricity tariffs shape the viability of V2G relative to simpler managed-charging strategies.
By examining these questions together rather than in isolation, the study provides a clearer signal about where bidirectional charging meaningfully outperforms managed charging and where it does not. In doing so, it helps explain why V2G appears compelling in some markets and marginal in others, and why progress toward scale has been uneven despite growing technical readiness across vehicles, chargers, and control systems.
Methodology: Modeling Bidirectional Charging as It Would Actually Operate
The analysis is grounded in detailed data from 50 battery electric vehicles, primarily Chevrolet Bolts and Tesla Model S vehicles, each observed for roughly one year between 2015 and 2020. Across nearly 50,000 parking events and more than 11,000 charging sessions, the authors identify when vehicles are parked at home, at work, or elsewhere, and how often they are actually plugged in.
One of the most important findings for V2G emerges here: vehicles are parked far more often than they are charging, especially at home and work. Daily driving distances are modest for most vehicles, leaving significant unused battery capacity on most days. In theory, this creates ample opportunity for V2G. In practice, that opportunity only materializes if vehicles are plugged in and if control systems can operate automatically during long parking windows.
To quantify the value of that flexibility, the authors develop an optimization model that allows vehicles to charge and discharge only when parked and plugged in, subject to state-of-charge constraints that ensure drivers can meet their next trip. The model explicitly evaluates V2G operation under different charging power levels and under three electricity pricing regimes: standard residential time-of-use rates (TOW), EV-specific TOU rates, and simulated real-time pricing adjusted to reflect consumer-side conditions.
Crucially for V2G, battery degradation is embedded directly in the optimization. Using real-world data from more than 1,800 Tesla vehicles tracked over nearly a decade, the authors apply a conservative linear relationship between cumulative energy throughput and battery depreciation. This approach likely overstates degradation during V2G, since bidirectional charging typically occurs at lower C-rates than driving, but it ensures that V2G value is not overstated.
The analysis is then applied across four utility service territories, PG&E in California, Con Edison in New York, Duquesne Light in Pennsylvania, and Austin Energy in Texas, chosen specifically to test how different rate designs and grid conditions affect bidirectional charging value.
Key Findings: Where V2G Works, and Where It Struggles
The most important finding for the bidirectional charging industry is that V2G value is overwhelmingly determined by rate design. In high-price, high-volatility regions such as California and New York, bidirectional charging delivers substantial net benefits. Even when drivers do not change their existing plug-in behavior, V2G often generates annual savings on the order of $1,500 to $3,000. When drivers plug in more consistently during long parking sessions, annual savings frequently rise into the $3,000 to $5,000 range.
Under idealized real-time pricing conditions, V2G value increases dramatically. In PG&E territory, the study finds that high-speed V2G operation can deliver more than $10,000 per year in gross value under perfect coordination, illustrating the upper bound of what bidirectional charging could provide when price signals are strong and flexibility is fully utilized.
In contrast, in regions with low or flat electricity rates, V2G struggles to distinguish itself from managed charging. In Duquesne Light and Austin Energy territory, incremental V2G value is often modest, frequently measured in the hundreds of dollars per year. In these markets, the study shows that managed charging captures most of the available economic benefit, leaving limited additional upside for bidirectional operation.
Charging power also plays a decisive role in how V2G performs. Across most regions, medium-power Level-2 charging, around 12 kW, emerges as the most cost-effective option once infrastructure costs and battery degradation are considered. While higher power increases theoretical flexibility, the returns diminish quickly, particularly given that mass-market bidirectional hardware at higher power levels is not yet widely available. For near-term V2G deployment, the study strongly reinforces the case for medium-power bidirectional charging as the practical sweet spot.
The study also sheds light on the often-assumed role of workplace charging in V2G. While vehicles are parked for long durations at both home and work, the data show that most energy, and most near-term economic value, is captured through residential charging, largely because vehicles are more consistently plugged in at home. Workplace locations, however, represent a significant source of untapped flexibility. Long, predictable daytime parking windows create an opportunity for employers to offer bidirectional charging options that allow employees to participate in V2G without relying solely on home infrastructure. The analysis suggests that while the incremental economic value of adding workplace bidirectional chargers is often modest under current plug-in behavior, improving access, automation, and participation at workplaces could meaningfully expand aggregate grid flexibility and complement home-based V2G as the technology moves toward scale.
Battery degradation, often cited as a fundamental barrier to V2G, emerges here as a manageable and quantifiable cost rather than a showstopper. The authors introduce the concept of “virtual miles” to describe the equivalent driving distance imposed on the battery by V2G cycling. In some scenarios, V2G can add tens of thousands of virtual miles per year. Importantly, however, in high-value markets, the economic gains from bidirectional charging generally outweigh these degradation costs.
The more significant issue raised by the study is not degradation itself, but the misalignment between cycling-based battery use and today’s mileage-based warranty frameworks, a challenge that becomes more acute as V2G scales.
Study Limitations
While the study’s methodology is notably grounded in real-world data, several limitations are important to acknowledge when interpreting the results. The analysis relies on a relatively small, non-random sample of 50 battery electric vehicles, primarily located in California and observed between 2015 and 2020. As a result, the findings may not fully represent driving behavior, charging access, vehicle models, or grid conditions in other regions or in more recent years as EV adoption has broadened. In addition, the optimization framework assumes perfect foresight of electricity prices and vehicle travel schedules, which represents an upper bound on achievable V2G value and does not fully reflect the operational uncertainty faced by drivers and aggregators in practice.
Battery degradation is modeled using a linear approximation derived from historical fleet data, providing a conservative and transparent estimate but not capturing nonlinear effects related to temperature, depth of discharge, or charging rate that may influence long-term battery health. The analysis also assumes full pass-through of V2G value from aggregators to drivers and does not explicitly model regulatory and market constraints such as interconnection rules, export compensation limits, or restricted access to wholesale price signals. Accordingly, the results should be interpreted as directional and comparative insights into bidirectional charging potential, rather than precise predictions of realized driver revenues under current market conditions.
What This Study Tells Us About Advancing V2G
The study provides several critical insights for advancing bidirectional charging beyond pilots.
First, the study underscores that V2G’s path to scale is inherently selective rather than universal. Value emerges only where retail rate structures create sustained incentives for flexibility, making market choice a strategic consideration rather than an afterthought. This helps clarify why pilot outcomes have diverged so widely across regions and suggests that successful commercialization will depend less on proving technical capability and more on aligning deployment with pricing environments that reward bidirectional operation.
Second, the analysis points to moderate-power bidirectional charging as the most credible foundation for early commercialization. Rather than chasing maximum dispatch capability, the results favor solutions that balance flexibility with cost, availability, and durability. This reinforces the role of residential and workplace locations—where vehicles already sit for long, predictable periods, as the natural starting point for scale, without requiring a step-change in power levels or infrastructure complexity.
Third, the study highlights that behavior and automation are as important as hardware. Much of the modeled V2G value only materializes when vehicles are plugged in during long parking sessions, underscoring the importance of default participation, low-friction user experiences, and aggregator-led optimization rather than active, ongoing driver engagement.
Finally, the introduction of “virtual miles” brings battery warranties into focus as a structural issue for scale. As bidirectional charging increases cycling without increasing odometer mileage, existing warranty frameworks become increasingly misaligned with how batteries are actually used. Resolving this tension will be critical for building confidence among automakers, fleet operators, and consumers as V2G moves beyond pilots.
Taken together, the study helps shift the V2G conversation away from abstract potential and toward practical readiness. It clarifies where bidirectional charging can create durable value today, what conditions are required to unlock that value, and which institutional barriers, not technical ones, now matter most. In that sense, it does not just evaluate V2G; it helps chart the path forward.
