Electric cars that power the grid

How far away is vehicle-to-grid, where parked electric cars send power back to homes and the grid, from routine use?

Vehicle-to-grid is in pilot use. A UK household tariff, a Dutch car-sharing fleet and US school bus projects are running, and the communication standard for two-way charging has been published. The gaps are battery wear in everyday use, which has not been measured over years, G99 grid-export certification for each car and charger set-up, and owner payments that may be too small to justify the extra equipment. No programme running at scale has been reported in the sources reviewed.

AI illustration · Illustrative scene, not a photograph of the specific device or experiment.
WHERE WE AREPilots

Close. Early pilots are running in the real world.

Two-way charging runs in several real settings: a UK tariff with one listed car and charger combination, a Dutch car-sharing fleet reported live with 50 cars, and US school bus projects. The communication standard is published, and one manufacturer was reported certified to G99 for grid export in the UK. The stage is pilot rather than scaling, because the sources reviewed report no programme of routine use at scale, no measured battery wear from cars in everyday use, and no measured grid-service volumes from the Utrecht scheme.

The tech tree

Everything recorded on Vrulum that this future needs, oldest foundations at the top and the goal at the bottom. Lines show what each step requires.

What it takes: Electric cars that power the grid Unlocked Being researched Locked
  1. 1856ManufacturingIndustrial steelmakingCommercial Unlocked.
  1. 1774ManufacturingPrecision machine tools and interchangeable partsCommercialRequires: Industrial steelmaking. Unlocked.
  1. 1967Modern systemsCar electronics and engine controlCommercial Unlocked.
  2. 3500 BCMovementThe wheel and axleCommercial Unlocked.
  3. 1712PowerThe steam engineCommercialRequires: Precision machine tools and interchangeable parts. Unlocked.
  4. 1859PowerLead-acid batteriesCommercial Unlocked.
  5. 1859PowerPetroleum refiningCommercial Unlocked.
  1. 1816ControlVehicle steeringCommercialRequires: The wheel and axle. Unlocked.
  2. 1827ControlClutches, gearboxes and differentialsCommercialRequires: Precision machine tools and interchangeable parts. Unlocked.
  3. 1902ControlVehicle brakesCommercialRequires: Car electronics and engine control. Unlocked.
  4. 1901ManufacturingAssembly-line mass productionCommercialRequires: Precision machine tools and interchangeable parts. Unlocked.
  5. 1952Modern systemsVehicle safety systemsCommercial Unlocked.
  6. 1956Modern systemsCatalytic convertersCommercial Unlocked.
  7. 1964Modern systemsSatellite navigation (GNSS)Commercial Unlocked.
  8. 1750MovementSprings and vehicle suspensionCommercialRequires: The wheel and axle. Unlocked.
  9. 1794MovementRolling bearingsCommercialRequires: Precision machine tools and interchangeable parts. Unlocked.
  10. 1844MovementVulcanised rubber and pneumatic tyresCommercialRequires: The wheel and axle. Unlocked.
  11. 1821PowerThe electric motorCommercialRequires: Industrial steelmaking. Unlocked.
  12. 1860PowerThe internal combustion engineCommercialRequires: The steam engine, Petroleum refining, Precision machine tools and interchangeable parts. Unlocked.
  13. 1976PowerLithium-ion batteriesCommercialRequires: Lead-acid batteries. Unlocked.
  1. 1769VehicleThe motor carCommercialRequires: The wheel and axle, Vulcanised rubber and pneumatic tyres, Springs and vehicle suspension, Rolling bearings, The internal combustion engine, The electric motor, Lead-acid batteries, Vehicle steering, Vehicle brakes, Clutches, gearboxes and differentials, Assembly-line mass production, Industrial steelmaking, Car electronics and engine control, Vehicle safety systems, Catalytic converters, Satellite navigation (GNSS), Lithium-ion batteries, Petroleum refining, Precision machine tools and interchangeable parts, The steam engine. Unlocked.
  1. 2017Vehicle-to-gridPilot and early commercialRequires: The motor car, Lithium-ion batteries. Unlocked.
  1. 2017Battery wear from daily V2G use measured over years in normal useNot started Locked.
  2. 2021Domestic two-way chargers tested in UK homesDone Unlocked.
  3. 2022Communication standard for two-way power transferDone Unlocked.
  4. 2024Grid-code certification for exporting power from a car in the UKIn progress Being researched.
  5. 2025Car-sharing fleet with two-way cars in public useIn progress Being researched.
  6. 2026Two-way charging on a mainstream EV in a single US homeIn progress Being researched.
  7. 2026School bus fleets returning power to the gridIn progress Being researched.
  8. Date not recordedHousehold V2G tariff in the UKIn progress Being researched.
  9. Date not recordedRoutine V2G at national scaleNot started Locked.
  1. GoalElectric cars that power the gridGoalRequires: Vehicle-to-grid, Domestic two-way chargers tested in UK homes, Communication standard for two-way power transfer, Grid-code certification for exporting power from a car in the UK, Household V2G tariff in the UK, Car-sharing fleet with two-way cars in public use, Two-way charging on a mainstream EV in a single US home, School bus fleets returning power to the grid, Battery wear from daily V2G use measured over years in normal use, Routine V2G at national scale. Locked.

The road so far

2 of 9 steps done, 5 in progress.

  1. Done · Mar 2021Domestic two-way chargers tested in UK homes

    Project Sciurus ran from April 2018 to March 2021. Cenex's project page gives a target of at least 300 domestic bidirectional chargers of 6 kWh, and says over 320 installations were completed by August 2020. The page gives no bill-saving or grid-revenue figures, so none are stated here. [2]

  2. Done · 26 Apr 2022Communication standard for two-way power transfer

    ISO 15118-20:2022 defines communication messages and sequence requirements for bidirectional power transfer between an electric vehicle and its supply equipment. Only the publicly visible scope on the IEC webstore page was read, not the full standard. [6]

  3. In progress · 19 Nov 2024Grid-code certification for exporting power from a car in the UK

    TÜV Rheinland reported on 19 November 2024 that Nissan's V2G technology had been certified to G99, the UK grid code for connecting generation equipment to the distribution network, including EVs exporting power. The release describes its testing in general terms and gives no specific test procedures. No other manufacturer's G99 certification was named in the sources reviewed. [7]

  4. In progressHousehold V2G tariff in the UK

    Octopus Power Pack is a V2G tariff open to a qualifying car and charger. The page lists one combination, a V2G-enabled BYD Dolphin with a V2G-enabled Zaptec Pro charger. Eligibility also requires a smart meter, a G99 certificate and plug-in availability of 12 hours a day on 20 days a month. The page is undated. [1]

  5. In progress · 16 Jun 2025Car-sharing fleet with two-way cars in public use

    A car-sharing scheme in Utrecht was reported live in June 2025 with 50 Renault 5 E-Tech cars, and 500 V2G-capable cars are planned. MyWheels runs the fleet, and We Drive Solar supplies the bidirectional public chargers. The reports give no measured results. [5][4]

  6. In progress · May 2026Two-way charging on a mainstream EV in a single US home

    The Mobility House and Wallbox interconnected a Kia EV9 with a Wallbox Quasar 2 bidirectional charger in a San Diego County home in May 2026, reported as the first residential bidirectional charger interconnected in that county. The report makes no statement about certification or warranty, and no national approval for the EV9 was found. [8]

  7. In progress · 6 Aug 2026School bus fleets returning power to the grid

    World Resources Institute figures relayed by WAMC put about 230 of the roughly 6,700 electric school buses on US roads at 8 MWh that can be returned to the grid at any one time. The broadcast does not describe that figure as an estimate. It describes the 74-bus fleet of Oakland Unified School District as adding an estimated 2.1 GWh of clean energy back to the grid each year. [9]

  8. Not started · 31 May 2017Battery wear from daily V2G use measured over years in normal use

    A University of Hawaii lab study by Matthieu Dubarry and colleagues, reported in May 2017, found that capacity loss in commercial cells rose 75% with two V2G steps a day and 33% with one. The percentages are reported without a stated baseline. The same report gives no long-term data from cars in normal use, and the sources reviewed contain no field measurements of that kind. [10]

  9. Not startedRoutine V2G at national scale

    No nationwide V2G programme with a measured share of grid flexibility was found in the sources reviewed. The Utrecht figure of 10% of regional flexibility is a projection from the project's promoter, not a measured result.

Why it matters

If parked cars can return power when the grid is under strain, they could reduce the need for dedicated storage and let more wind and solar be used. The result depends on whether owners keep their batteries healthy and whether the payments justify the extra equipment. The answer will shape how grid operators, car makers and energy suppliers plan charging.

What stands in the way

  • Battery wear from discharging is not settled. Lab work on commercial cells reports faster capacity loss, and no measured data from cars in normal use were found.
  • Export to the grid needs G99 permission for each car and charger set-up. Only one manufacturer's G99 certification was reported in the sources reviewed.
  • Owner earnings look small. The Catapult project's modelling put a typical residential 7 kW charger at about £100 a year, and over £400 only in ideal circumstances. No source reviewed gives the cost of the extra equipment, so the comparison is not made here.
  • Few cars and chargers qualify. The Octopus tariff lists one combination, and the Utrecht fleet is still being built out.
  • Octopus requires a smart meter before a household can join its tariff, and the car, charger and operator need compatible communication, which ISO 15118-20 covers.

Published forecasts

What others have predicted. These are their estimates, not ours.

WhoForecastTimeframeMade
Energy Systems Catapult, Vehicle to Grid Britain project (modelled)Modelled outputs for Great Britain: V2G could save an additional £40 million to £90 million a year by 2030, and could save £270 million in cumulative distribution network investment by 2030. These are scenario outputs from the project, not measured results, and the page does not label each figure separately. [3]20301 Oct 2018

Signals to watch

  • Measured grid-service volumes from the Utrecht car-sharing scheme, rather than projected flexibility.
  • Further G99 certifications for other car makers, and more car and charger combinations on the Octopus Power Pack tariff.
  • Multi-year battery ageing data from two-way cars in normal use, from a source that publishes methods and sample sizes.
  • Measured, rather than estimated, V2G output from US school bus programmes.
  • A car maker stating V2G approval or warranty coverage for a mainstream model in a named market.

Sources

  1. company announcement
    Octopus Power Pack
    Octopus Energy, 2026.
  2. other
    Sciurus: Domestic V2G Demonstration
    Cenex, 2021.
  3. other
    Vehicle-to-Grid GB: Decarbonising Britain
    Catapult Energy Systems, 1 Oct 2018.
  4. news
    Utrecht to host vehicle-to-grid car sharing service
    Patrick Jowett. pv magazine, 28 Nov 2024.
  5. news
    Vehicle-to-Grid-enabled car-sharing service goes live in Netherlands city
    Charles Morris. Charged EVs, 16 Jun 2025.
  6. standard
    Road vehicles - Vehicle to grid communication interface - Part 20: Network and application protocol requirements
    International Electrotechnical Commission (IEC) webstore, 26 Apr 2022.
  7. company announcement
    First G99 grid code certification
    TÜV Rheinland, 19 Nov 2024.
  8. news
    Really quick charge: The Mobility House, V2G and building up the grid
    Jo Borrás. Electrek, 8 May 2026.
  9. news
    School buses for emergency power
    WAMC (Earth Wise), 6 Aug 2026.
  10. news
    New study finds V2G discharging harmful to EV batteries
    Matthieu Dubarry. Charged EVs, 31 May 2017.

Last reviewed 21 Oct 2026.