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Most cars are idly parked 90-95% of the time. With an accelerated shift to using electric vehicles (EVs), batteries of EVs offer enormous potential in terms of using their vast collective storage capacity as a flexible solution to support the grid, which can be taxed with an intermittent renewable energy supply. Bi-directional electric vehicle charging (V2X) refers to EV chargers that allow not only for charging the battery of the EV but also for taking energy from the car battery and pushing it back to the grid when needed.

There are two primary receivers of power from an EV: the grid (V2G) and the electricity from a home or building (V2H). Bi-directional charging creates greater synergy between the clean transport sector and renewable energy sources, as the car batteries can store excess energy created by variable renewable sources, such as wind and solar, and then provide power to the grid or home when demand is high or energy production is low. This reduces curtailment, lowers the need for grid infrastructure investments and allows for higher renewable energy integration. In addition, V2H charging can act as an emergency power source during power outages, and V2G can provide vehicle owners with extra income through arbitrage of time-variable energy prices.


Problems to be solved


Grid congestion Growing energy consumption Fluctuating generation of renewables Uneven peaks in energy usage




The main goal of bi-directional electric vehicle charging is to increase the grid flexibility. Thereby, it increases potential revenue streams through arbitrage or provision of ancillary services and the integration of solar PV as well as the self-reliance in case of electricity blackouts while enabling the optimisation of smart micro grids. In addition, the solution achieves the benefits listed below. While some benefits are likely to be fulfiled with a basic implementation of the solution, the fulfilment of the additional potential benefits depends on the functions implemented in a specific project.

Main Benefits
  • Improving energy supply efficiency

  • Shaving peak energy demand

  • Enhances grid stability

Potential Benefits
  • Reducing use of fossils

  • Reducing GHG emissions

  • Increasing share of renewables

  • Decreasing energy consumption in buildings


Functions help you to understand what the products can do for you and which ones will help you achieve your goals.
Each solution has at least one mandatory function, which is needed to achieve the basic purpose of the solution, and several additional functions, which are features that can be added to provide additional benefits.

Mandatory Functions
    Charging electric vehicles

    Bi-directional charging enables charging of electric vehicles

    Storing electricity into car battery

    Bi-directional charging enables not only to charging but also storing electricity in a car battery

    Feeding energy from the battery back into the grid

    Bi-directional charging enables feeding energy back into the grid

    Managing energy supply and demand

    Products that manage energy supply and demand

    Providing flexibility to the grid (V2G)

    With suitable control, flexibility is provided to the grid

Potential Functions
    Providing backup power (V2H)

    Products and services that enable the use of the EV as a backup power source

    Using the EV battery for balancing and frequency control

    Products and services that enable use of the battery of the EV to balance and control frequencies

    Informing customers

    Products that inform the customer about the services

    Paying for the energy fed back into the grid

    Services that enable payment for energy fed back into the grid

Products offering these functions

Vehicle-to-Grid Optimisation Solution from CENERO

Electric propulsion systems will significantly shape and change the future of mobility. Our V2G optimisation concept demonstrates bidirectional charging to enhance grid stability.


The variants of bi-directional charging concern whether power goes from the vehicle to the grid (V2G) or to a building or home (V2B or V2H).


The smart grid controls vehicle charging and returns electricity to the grid. The transmission system operator may be willing to purchase electricity from customers at times of peak demand or to use the EV battery capacity for ancillary services such as balancing and frequency control.

Supporting City Context

Cities with high solar photovoltaic (PV) generation profiles benefit more from bi-directional charging than those with high wind generation profiles because solar energy is generated and stored during the day and then can be dispatched at night when the vehicle is connected to the grid. Other supporting factors include dynamic electricity pricing and competitive ancillary service markets. (IRENA, 2019)

Use Cases



Vehicle to X (V2X) Charging for Electric Vehicles

In Barcelona, an innovative form of Vehicle-to-X (V2X) charging for Electric Vehicles has been implemented. This can increase the renewable energy penetration, energy storage, grid flexibility and facilitate energy management optimization.



The Parker Project- V2G Services

The Parker project tested the validity of a company fleet with Vehicle to Grid (V2G) services to support the power grid and support greater integration of renewable energy, whilst earning revenue.


Vehicles supply supplemental power to the building or home. This does not directly affect grid performance but rather provides a back-up power supply. It can also help the vehicle owner to avoid demand charges or increase the usage share of power produced on-site by distributed generation.

Supporting City Context

In the aftermath of the Fukushima disaster, commercial V2H has been available in Japan since 2012 to provide emergency electricity in case of a power outage. Market deployment has not yet been reached elsewhere.

Cost Structure

The costs of a bi-directional electric vehicle charging system occur due to the interface costs, which are 3-5 times higher than that of unidirectional smart charging. Additionally new hardware is neccessary and the batteries might be degredated more quickly.

City Context

As cities generate more and more renewable energy to reach their carbon neutrality targets, bidirectional charging offers a cheaper energy strorage system to balance and optimize the grid. However, for bi-directional charging to be successful in a city, there must be regulations and policy supporting such a solution:

  • For V2G technology to be enticing enough to be deployed at a high scale, EV owners must be able to ‘stack’ revenue streams from the flexibility services their car battery provides. A Danish pilot project found revenue streams of an average 1860 EUR per year (Andersen, 2021).
  • There also needs to be a high level of EV deployment in the city with the same V2X capabilities to enable aggregation of the EV batteries to create a sort of virtual power plant.
  • The EV charging stations and distribution networks need to be interoperable to prevent vendor lock-in and allow for cost-effective connectivity between EVs and diverse charging infrastructure.
  • Studies have additionally shown that solar-based electricity systems see the most incremental benefits from bidirectional charging.

As the technology is new, cities can promote sustainable behavior by building the infrastructure on a small scale (e.g. the municipal fleet) with the intention to build on the solution long-term. In addition, to support wide scale deployment of bi-directional charging, newly planned charging stations should be ‘smart’ chargers that are capable of facilitating the grid service described with the V2X solution.

Supporting Factors

  1. High EV deployment so EVs can be aggregated
  2. Regulation that enables price signals to optimise charging and discharging
  3. Interoperability between EVs, charging stations and distribution networks

Government Initiatives

  • In the UK, only home charge points that use smart technology are eligible for government funding under the Electric Vehicle Homecharge Scheme. (IRENA, 2019)
  • The EU Clean Energy Package removes ‘double charging’ fees for drawing and injecting power into the grid. (IRENA, 2019)

Stakeholder Mapping

Stakeholder Map of a Bidirectional Electric Vehicle Charging System (BABLE, 2021)

Market Potential

According to Germany’s Centre for Solar Energy and Hydrogen Research (ZSW), 5.6 million EVs were on the world’s roads as of the beginning of 2019. If most of the passenger vehicles sold from 2040 onwards were electric, more than 1 billion EVs could be on the road by 2050. This would mean that by mid-century around 14 terawatt-hours (TWh) of EV batteries would be available to provide grid services, compared to a projected 9 TWh of stationary battery capacity. EVs typically only need to charge for 10% of the time they stand idle and are parked 95% of the time, leaving 85% of their lifetime to, in theory, provide grid flexibility services (Mohammadi, 2019).

Cost Structure

Bi-directional charging points are still a nascent technology and very few are on the market. Thus, the cost structure varies widely and is expected to change as the technology matures.

Data and Standards

  • International norms to standardise V2X charging technology include IEC 63110 and IEC 61850 (IRENA, 2019)
  • An updated version of the ISO 15118 – 2 standard, which is concerned with communication between EV and a charging station, is expected to be released in Europe in 2021(ISO 15118-20). This will enable ‘Plug & Charge’ functionality. (IRENA, 2019)

The creation of this solution has been supported by EU funding

Use Cases



Vehicle to X (V2X) Charging for Electric Vehicles

In Barcelona, an innovative form of Vehicle-to-X (V2X) charging for Electric Vehicles has been implemented. This can increase the renewable energy penetration, energy storage, grid flexibility and facilitate energy management optimization.



The Parker Project- V2G Services

The Parker project tested the validity of a company fleet with Vehicle to Grid (V2G) services to support the power grid and support greater integration of renewable energy, whilst earning revenue.

Related solutions

Public Charging System for Electric Vehicles

The current EU regulation on emissions for cars is the strictest worldwide. Along with further restrictions the thresholds cannot be meet with conventional cars only anymore. One alternative technology, reducing the local emissions, are electric vehicles.

Building Energy Management System

According to the Energy Performance of Buildings Directive (EPBD), buildings are responsible for approximately 40% of energy consumption and 36% of CO2 emissions in the EU.

Urban Resilience

Urban resilience is the ability of an urban system and all its constituents across temporal and spatial scales to maintain or rapidly return to desired functions in the face of a disturbance.

Citizen Engagement

Citizen engagement plays an instrumental role in the way human settlements are governed. Decision-making processes are enhanced by engaging those most affected and intimately connected with societal challenges.

Smart Microgrids

Microgrids are emerging as an attractive, viable solution for cities, utilities, and firms to meet the energy needs of communities by leveraging more sustainable resources, while increasing resilience, reducing emissions, and achieving broader policy or corporate goals.

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