How electric vehicles could back up our power system
Cell Press
Electric vehicles (EVs) could do more for our environment than simply replace gasoline. Publishing in the Cell Press journal Joule on April 2, a new assessment of EV charging strategies suggests that EVs could serve as a vast network of mobile batteries, storing excess energy and feeding it back into the grid when demand surges. This approach could ease grid strain, cut emissions, and create revenue—but only if gradually paired with timely grid upgrades.
“People have debated whether electric vehicles are truly green and sustainable because much of our electricity still comes from fossil fuels,” says senior author and energy engineer Ziyou Song of the University of Michigan. “At the same time, the grid is struggling to absorb intermittent and unpredictable renewable energy sources like solar and wind.”
Vehicle-to-grid (V2G) technology—software that allows charging stations to communicate with the grid—bridges both challenges, allowing EVs to both draw power and send it back when needed. This two-way energy flow contrasts with current charging systems, where electricity flows only from the grid to the vehicle. However, critics question the feasibility of large-scale V2G deployment and the high upfront costs of the necessary infrastructure.
To assess the real-world potential of V2G, researchers examined the San Francisco Bay Area under different grid scenarios. They projected EV ownership and solar energy adoption, mapped when and where vehicles would charge, and evaluated the cost-effectiveness of upgrading the grid proactively versus in phases.
“I was surprised by the results,” says Song. “The optimal solution is to upgrade the power system as soon as possible.”
If the grid is updated proactively, each charger would need to generate just $0.12 to $0.18 per day to offset V2G costs, compared to $1.49 to $1.78 under phased updates. Under California’s proposed decarbonization policies, the model estimates that annual carbon emissions between 2030 and 2045 could be reduced by up to 59,200 metric tons of CO2 equivalent with V2G and proactive upgrades. The strategy could also yield up to $47.5 million in cumulative carbon rebate revenue, supporting the economic case for V2G adoption.
“First, we need to upgrade the power system to support incoming electric vehicles,” says Song. “Then we can scale V2G when needed. That’s really the key message.” Major grid assets, such as transformers, last for decades, while V2G chargers have a limited lifetime and can be scaled up as EV adoption grows.
The team notes that much of their work relies on forecasts, such as how many EVs will be on the road in 20 or 30 years, what policies will look like, and how quickly rooftop solar will spread. Political shifts, especially regarding EV incentives, could change the timeline.
“V2G is a promising technology to handle many issues in the power system, especially as we integrate more renewable energy,” says energy engineer and co-author Shunbo Lei of the Chinese University of Hong Kong, Shenzhen.
“As renewables grow, we face imbalances of different timescales. I envision that EVs could play an important role in energy storage coordination to build a reliable power system.”
###
Joule, Xu et al., “Proactive grid investment enables V2G for 100% adoption of electric vehicles in urban areas” https://www.cell.com/joule/fulltext/S2542-4351(26)00077-2
Joule, published monthly by Cell Press, is a home for outstanding and insightful research, analysis, and ideas addressing the need for more sustainable energy. A sister journal to Cell, Joule spans all scales of energy research, from fundamental laboratory research into energy conversion and storage to impactful analysis at the global level. Visit http://www.cell.com/joule. To receive Cell Press media alerts, contact press@cell.com.
Journal
Joule
Method of Research
Computational simulation/modeling
Subject of Research
Not applicable
Article Title
Proactive Grid Investment Enables V2G for 100% Adoption of Electric Vehicles in Urban Areas
Article Publication Date
2-Apr-2026
Reduce infrastructure costs of EV adoption by upgrading grid first, then adding V2G chargers
Vehicle-to-grid (V2G) chargers enable utilities to use EVs like a mobile battery network, but when and where they are deployed will determine how cost-effective they are
Photos of charging vehicle and solar panel
Key takeaways
Vehicle-to-grid (V2G) chargers enable electric vehicles to behave as a battery network, potentially helping to level out electricity demand throughout the day.
Since this cannot completely offset the increased demands on the grid from EV adoption, the grid should be upgraded first, with V2G charging added later.
The analysis by a team from the National University of Singapore, the Chinese University of Hong Kong, Shenzhen, and University of Michigan Engineering calls for grid upgrades targeting long-term demand expectations to reduce the total costs.
Vehicle-to-grid chargers, which enable grid operators to use plugged-in electric vehicles as a battery network, could help utilities distribute electricity more efficiently. But even with advanced chargers, existing infrastructure cannot supply enough electricity to growing numbers of EVs, computer models from an international team of researchers suggest.
The research team recommends focusing on grid upgrades that plan for anticipated power needs 30 years ahead, while installing cheaper, basic chargers now. Then, when more EVs are on the road, future charger buildouts should prioritize V2G, enabling the upgraded grid to make the most of the expanding fleet of grid-connected batteries.
The study was led by a University of Michigan Engineering researcher, working with colleagues at the National University of Singapore and the Chinese University of Hong Kong, Shenzhen.
Advanced chargers that support vehicle-to-grid (V2G) electricity flow could help smooth out the electricity demand that power plants must meet, as demand rises and falls throughout the day. For example, the vehicles of people who charge at home could discharge after their commutes to help with the evening demand peak and then charge up overnight. Participating drivers could charge their EVs for free or even be compensated for the use of their vehicle battery.
However, this picture is more complicated in urban areas, where home chargers may not be available, and daytime charging adds to the peak. Local solar energy changes the calculation again, with charging vehicles able to store energy when the sun is high and release it at other times of day. The research team wanted to get a handle on what all this means for the grid.
"V2G has been discussed for the past 20 years, and we all know that it is useful in some contexts, but nobody has clearly demonstrated what context that is. Our study lays a foundation to express the context that maximizes V2G capability," said Ziyou Song, U-M assistant professor of electrical and computer engineering and co-corresponding author of the study in Joule.
Case study: EV and solar projections plus census data
The team dug into data from California's Bay Area, which has already seen enthusiastic EV adoption. More than 25% of new cars registered in the area were EVs in 2024. Using census data, the researchers modeled factors such as when households were likely to begin using an EV, where they would likely charge it, potential solar panel installations and the projected rise in baseline energy demand.
They tried different circumstances for the charging build-out, with basic chargers that allow the car to draw energy on demand, those that allow the grid to provide energy anywhere within a set time window, and the V2G chargers that provide power to the vehicle or draw power from it, depending on the needs of the driver and the utility. They also experimented with likely solar panel installations.
With this information in hand, the researchers looked at various approaches to upgrading the grid. In one case, they gamed out installing next-level transformers, transmission lines and other equipment as needed in the near future. In another, they upgraded to match the projected needs of 2050, when nearly all California vehicles are expected to be electric.
"V2G can be a powerful tool for reducing emissions and grid stress, but it isn't a silver bullet. The most cost-effective path forward requires strategically pairing progressive V2G adoption with forward-looking grid investment," said Shunbo Lei, assistant professor of electrical engineering at the Chinese University of Hong Kong, Shenzhen, and co-corresponding author of the study.
The research team had anticipated that upgrading charging infrastructure to V2G might delay the need for grid upgrades, and it can, but they found that the smarter money is on upgrading the grid with 2050 in mind as soon as upgrades are needed. The key reason is that chargers last about a decade, while transformers have expected lifetimes of up to 40 years. Upgrading a transformer in 2030 and again in 2045 represents a significant loss compared to doing a larger upgrade once. In contrast, building out V2G offers a much bigger payoff when more EVs and solar panels are deployed.
"If grid upgrades are inevitable, relying on V2G to delay them is not the most cost-effective approach. In fact, upgrading the grid early turns out to be the more economical strategy in the long run," said Lingcai Xu, first author of the study and a postdoctoral research fellow in the department of built environment at the National University of Singapore.
Beefing up the grid early means that the initial charger build-out can be done with cheaper, basic chargers, and those can be replaced in a decade or so when the advantage V2G capability more than pays for the cost of the charger. V2G will shine particularly when local solar panels can store energy in the local EV network, reducing the load on transmission infrastructure.
Study: Proactive grid investment enables V2G for 100% adoption of electric vehicles in urban areas (DOI: 10.1016/j.joule.2026.102393)
Journal
Joule
