V2G: vehicle to grid
What is V2G technology?
Imagine an electric car that can share its energy with the electrical network. Vehicle-to-grid (V2G) technology enables an electric vehicle to function as a battery and supply energy to a home or feed it back into the electrical network. This brings together the electricity and automotive sectors to optimise energy consumption – all in a society that is undergoing rapid electrification.
V2G, or vehicle-to-grid technology, offers the possibility of using electric cars as if they were stationary batteries, capable of storing electrical energy via a charging point and moving around without emissions, but also of feeding it back into the electrical network. In this case there are two options: feeding it back into the electrical network so that those kilowatt-hours can be used elsewhere in the electrical network or using it directly in the vehicle owner's home.
The aim is for electric mobility to become the future of transport, enabling journeys – long or short – to be made using electricity rather than fossil fuels such as petrol or diesel. But technology has gone a step further, and amid the electrification of society and industry, electric vehicles can become allies for optimising energy consumption beyond transport thanks to V2G technology.
In this way smart grids and electric mobility could work together to create a more sustainable, resilient and autonomous system, turning any car into a battery on wheels, provided that the facilities are ready for it.
In this regard, European DSOs are moving decisively towards the integration of V2G, promoting standardisation, certification and interoperability so that electric vehicles can offer flexibility to the electrical network in a safe and coordinated manner. Bidirectional charging and V2X vehicles (Vehicle-to-everything) are already being incorporated into new network codes, with strong collaboration between distribution and transmission network operators and charging operators to harmonise protocols and facilitate mass adoption.
How does V2G work? A bidirectional energy exchange
Unlike a normal charging point, where electrical energy is transferred through the plug to the vehicle until the battery is fully charged, V2G technology is characterised by its bidirectionality. For this to exist, the infrastructure must be prepared for it, offering the possibility of intelligently managing the battery charge – in this case of the electric car – and returning it to the electrical network at the right time.
The essential elements for installing a vehicle-to-grid system are as follows:
An electric car with a bidirectional charging system
Not all vehicles on the market have this capability. To implement a V2G system it is essential that the charging and battery system be able to receive and share energy. Several major manufacturers are already implementing this technology in their models.
A suitable charger and connectors
Both the charger and the connectors must be compatible with a bidirectional charging system.
An intelligent control system
As well as hardware, V2G systems must have various software programs to control different aspects. A smart grid is also recommended to charge at off-peak times and release stored energy when it is most beneficial. Likewise, batteries must have a Battery Management System (BMS) that authorises charging and discharging and ensures system stability (by monitoring temperature, degradation, power, etc.).
SEE INFOGRAPHIC: How bidirectional V2G charging works [PDF]
The useful life of a car battery with V2G systems
One of the fears about the implementation of this technology is related to the possible degradation of the electric vehicle battery when subjected to so many possible charging cycles. And although this is a valid concern given what is known about the charging cycle limits of other batteries or electric vehicles in operation, recent studies show vehicles that its impact can be very limited and even similar or slightly lower than that of conventional charging when charging levels are well managed (smart charging).
What are the main benefits of vehicle-to-grid (V2G)?
Although this is a nascent technology, its adoption and development is expected to generate benefits for both drivers and electrical networks.
Electric vehicles become distributed electricity storage
Thanks to V2G technology a car can become a way of storing electrical energy to be used later for transport, to supply a home or business or to be fed back into the electrical network, optimising its owner's energy expenditure and consumption.
Improving energy resilience
In the event of a failure in the electrical network, having a battery makes a huge difference, especially in areas with extreme temperatures or isolated locations. An electric vehicle connected to the electrical network can offer this service in addition to its characteristic mobility, guaranteeing power supply to its user for several hours, depending on the type of vehicle battery and the loss that occurs in the converter.
In addition to this physical resilience, V2G can become a strategic asset for national security: by distributing storage capacity across thousands of connected vehicles, the electrical system becomes less vulnerable to hacking or attacks targeting centralised infrastructure. Technical literature highlights that V2G introduces new cybersecurity challenges but also emphasises that if managed properly, a network with distributed resources can make it difficult for an isolated attack to cause a massive blackout and allows for responses more flexible and segmented to digital incidents.
Flexibility for networks
Vehicle to Grid will drive the incorporation of batteries capable of storing electricity produced by renewable sources at times of peak production and releasing it when needed through a decentralised and mobile network.
Savings on your bill
Whether it is a single vehicle or a fleet — in the case of a business — V2G or V2H/V2B (Vehicle to Home and Vehicle to Building respectively) technology contributes to improving energy efficiency and reducing costs.
Support for decarbonisation
Batteries are emerging as a very attractive option for creating flexible solutions that enable the expanded use of renewable energies, especially solar photovoltaic and wind power, whose intermittent nature prevents a continuous and stable supply throughout the day. To cope with market fluctuations and move away from fossil fuels, we need to incorporate more batteries into the electrical network to reduce dependence on this energy source and enable the use of electricity from renewable generation.
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Comparison between V2G and other storage technologies
There are various energy storage technologies that can be used to conserve surplus energy and use it later, increasing the efficiency of any home or building. V2G promises to become an option that combines mobility and storage to create a more decentralised and resilient network, but it is not the only option available for storing energy. BESS batteries or virtual batteries allow surplus energy to be stored in both buildings and homes, facilitating the maximum use of energy produced through renewable sources, especially photovoltaic solar.
SEE INFOGRAPHIC: Advantages and challenges of electrical energy storage technologies [PDF]
What are the main regulations and market prospects?
The legislative framework currently regulating Vehicle to Grid (V2G) technology varies depending on the geographical area. This inequality in legislating on this technology is due to the complexity of its implementation, as there are four important players to consider: the user, the mobility service provider or EMSP, the charging point operator CPO and the aggregator or energy market.
At European level, developers must take several standards into account when developing this technology. On the one hand, the Directive (EU) 2019/944 promotes a consumer-focused internal market and actively includes consumers through aggregation so that they can contribute surplus electricity for self-consumption to the energy mix. On the other hand, the Regulation (EU) 2019/943 states that tariffs should not discriminate against or discourage energy storage or aggregation with the aim of promoting a more flexible energy system, in which batteries of all types play a leading role. But perhaps the most relevant regulation of all is the Directive (EU) 2023/2413, which considers bidirectionality and smart charging as a measure of flexibility and renewable energy utilisation, which directly affects V2G, putting it on the map as an emerging technology to be taken into account.
Regulation of mobility with alternative fuels is also advancing in legislation with Regulation (EU) 2023/1804, which focuses on improving the user experience and the availability of charging points for these new types of vehicles.
This legislative support reduces structural barriers and supports bidirectional charging so that EVs (electric vehicles) can act as flexible resources for the electrical network. However, adoption is gradual because it requires a substantial upfront investment and depends on offers promoted by aggregators and agreements with manufacturers and charging points.
In the case of the United States, FERC Order No. 2222 promotes the inclusion of distributed energy sources in electrical networks, although its application is uneven across the country. However, this regulation is fundamental for V2G, as electric vehicle batteries would be included in this type of distributed energy source.
In Spain an amendment to Royal Decree 244/2019 has recently been presented which definitively opens the door to bidirectional charging. This draft from MITECO regulates the use of electric vehicles as distributed storage, allowing users to feed energy into their homes or the grid without financial penalties. With this change, electric cars are no longer simply receivers but have become a key part of national energy management.
In addition to the various regulations in the main territories it is important that this new technology complies with safety standards to ensure responsible and safe use for all. Some of the standards to be taken into account are the ISO 15118, which defines the high-level communication (HLC) standard between an electric vehicle (EV) and its charger (EVSE) to safely coordinate charging and discharging to the grid or to a building. This establishes the parameters for promoting smart charging, which allows charging and discharging profiles to be optimised and programmed, preferences to be set and time windows to be exploited so that the use of this electricity is as efficient as possible.
In this regard the Iberdrola Group already has technology in place for when V2G becomes a reality in the market. The Advanced Smart Assistant is designed to optimise the charging of electric vehicles and is intended to incorporate bidirectionality in the future facilitating the use of this type of car as storage batteries. It predicts that one in 10 electric vehicles will use bidirectional charging in Spain by 2050.
Commercial maturity of V2G
Although many countries are still in the testing phase, a few have moved from pilot projects to actual commercial V2G offerings thanks to advanced regulatory frameworks, dynamic tariffs and access to ancillary services markets.
One example of this is France, which stands out for offering the first V2G product for private customers in Europe, where Renault 5 owners, together with a specific wall box, can participate in the electricity market and be remunerated for making their battery available to the system thanks to a project developed by Renault and The Mobility House. In the Netherlands, Utrecht is making great strides: car-sharing company MyWheels is integrating the first 500 electric Renaults compatible with V2G, operated by We Drive Solar, which provide network stability services and already generate revenue thanks to this new flexibility in the system.
The future of V2G and opportunities for innovation with Iberdrola
The future of V2G depends largely on advances in legislation to make it an attractive option for drivers and safe for the grid. Despite the many benefits, the technology developed must properly balance this new decentralised model through intelligent demand management. This poses challenges in coordinating all the sectors involved, not only at the regulatory level but also at the technological level. Despite this, many manufacturers are already incorporating this option into their new vehicles, preparing for a future in which bidirectional charging will be the norm as the implementation of electric mobility grows worldwide. For example, Iberdrola, E.ON and BMW are leading a working group dedicated to promoting this technology in energy communities, within the Coalition of the Willing.
What’s more, we are taking the first steps to incorporate this technology into some of our projects. This is the case of Noronha Verde, located in Fernando de Noronha (Brazil), a World Heritage Site, which will transform it into the first inhabited oceanic island in Latin America with a highly sustainable energy model, including mobility. With this in mind the project team has installed several V2G charging points on the island that will enable the fleet of 14 vehicles to be converted into a flexible storage network. In Spain the team also carried out various tests at the Iberdrola Campus in San Agustín de Guadalix with bidirectional charging points with the aim of identifying their value in a hypothetical fully renewable scenario.