Vehicle-to-grid (V2G) chargers allow electric vehicles to function as a distributed battery network, enabling electricity to be stored and returned to the grid when needed. This capability has the potential to smooth fluctuations in demand throughout the day, for example, by supplying power during evening peaks and recharging overnight. In principle, such systems could improve efficiency for utilities while offering incentives to EV owners, such as reduced charging costs or financial compensation for supplying energy back to the grid.

However, modelling from an international team of researchers indicates that V2G alone cannot fully offset the additional strain that widespread EV adoption places on existing electricity infrastructure. Even with advanced charging technologies, current grid systems are not equipped to handle the projected growth in electricity demand. As a result, relying on V2G to delay or substitute for grid upgrades may not be sufficient or cost-effective in the long term.

The researchers instead recommend prioritising early investment in grid infrastructure, with upgrades designed to meet long-term demand projections. Their analysis suggests that planning for future electricity needs—looking as far ahead as 2050—can reduce total system costs by avoiding repeated, incremental upgrades. While V2G technology remains valuable, it is most effective when deployed alongside a grid that has already been strengthened to accommodate increased loads.

The study examined detailed data from California’s Bay Area, where EV adoption is already high. Using census data and projections, the team modelled when households are likely to adopt EVs, where charging would occur, and how factors such as rooftop solar installations and rising baseline energy demand would influence electricity use. They compared different charging strategies, ranging from basic chargers to more advanced systems capable of flexible timing and bidirectional energy flow.

Their findings highlight that infrastructure lifespans play a crucial role in determining cost efficiency. Grid components such as transformers can last up to 40 years, whereas EV chargers typically have a lifespan of about a decade. This means that delaying major grid upgrades in favour of incremental improvements can lead to higher cumulative costs, as equipment may need to be replaced or upgraded multiple times. In contrast, undertaking larger, forward-looking upgrades early can avoid these inefficiencies.

The research also underscores that the benefits of V2G increase as EV adoption and renewable energy generation expand. In areas with significant solar power, for instance, EVs can store excess energy generated during the day and release it when demand rises, reducing pressure on transmission systems. This makes V2G particularly valuable in a mature energy ecosystem, rather than as a stopgap solution during early adoption phases.

Overall, the study concludes that the most cost-effective pathway is to upgrade the grid first and introduce V2G capabilities more gradually. By initially deploying simpler, lower-cost chargers and transitioning to advanced V2G systems later, utilities can better align infrastructure investments with evolving demand. This staged approach ensures that both grid capacity and charging technology develop in tandem, maximising efficiency while minimising long-term costs.

More information: Liangcai Xu et al, Proactive grid investment enables V2G for 100% adoption of electric vehicles in urban areas, Joule. DOI: 10.1016/j.joule.2026.102393

Journal information: Joule Provided by University of Michigan