Electric vehicles connected to home networks and the power grid, with their batteries used to ensure stability by storing excess energy and feeding it back at times of peak demand – this is V2G.
Electric vehicle batteries have enormous potential, which goes beyond their main purpose of supplying energy for mobility. Batteries can also be connected to the general power grid to make it more stable and efficient. This is the principle that underpins Vehicle-to-Grid (V2G), a technology that helps turn electric cars from a simple means of transport into energy storage facilities, capable of exchanging energy with the grid.
As a result of bidirectional charging technology, an electric vehicle’s battery pack will be able to make the network more stable, storing excess energy and feeding it back when required. This will bring benefits to society, to energy operators, and to drivers of plug-in cars.
Batteries serving the grid
In some ways, every electric vehicle user could become an energy provider. That’s because during recharging, the car’s battery will be deployed as energy storage facility connected to the grid.
That will allow the grid to become more efficient, boosting people’s own electricity consumption and optimizing how energy is produced and consumed at a local level, not forgetting that V2G will mean electric vehicle users could also receive economic benefits for the services they provide.
As the number of electric vehicles connected to the grid increases, so too will energy storage capacity. This will allow renewable sources such as solar and wind to be integrated effectively and affordably.
At present, these sources cannot guarantee a constant production of electricity – wind turbines and solar farms are often shut down when power generation exceeds current demand. As it will be possible to store excess green energy using the batteries of electric cars, V2G will allow facilities such as these to operate continuously.
At the heart of V2G systems’ technology is a bidirectional power inverter which connects to the car’s high-voltage battery while simultaneously also connecting to the grid, but at low voltage.
The device can either take energy from the grid to recharge the battery, or provide energy to the grid by taking it from the vehicle’s battery.
The flow of energy is managed by a control unit which takes into account the grid operator’s demands or the energy status of the building the car is connected to, fitting this around the recharging schedule the user has set.
The situation in Italy
For what concerns V2G in Italy, the situation has changed in recent months, after measures in a decree from the Ministry of Economic Development (passed on 30 January 2020) were implemented. The decree lays out standards and procedures to facilitate the roll-out of technology to integrate battery vehicles with the power grid.
As a consequence, the Italian Regulatory Authority for Energy, Networks and Environment (ARERA) published the rules for charging points equipped with V2G technology and the updating of the electricity grid. The aim is to boost the numbers of electric vehicles providing energy to the general power grid by implementing Vehicle-to-Grid and via the launch of the first pilot projects.
Over the next few years, Volkswagen will introduce bidirectional charging on its electric vehicles and charging solutions step by step, in accordance with the ISO 15118 international standard (currently being updated), which requires the use of CCS connectors.
To begin with, electric cars will be integrated into the home network (Vehicle-to-Home, V2H). The potential is considerable. For example, it will be possible to charge the electric car in a targeted way when electric power costs less and excess power is available, while delivering power to the home at times when electricity is more expensive; used in combination with a photovoltaic system, theoretically it could even make the home autonomous in terms of energy. The entire system will be controlled by a digitally networked home energy management system (HEMS) combined with a bidirectional wallbox.
The next step is connecting electric vehicles to the general power grid. This will require dedicated infrastructure, amendments to th relevant legislation, and investments in the digitalisation of the power grid, with intelligent systems capable of coordinating the interaction between a number of different elements, ranging from infrastructure to the vehicle itself.
Where is excess power available? Where do bottlenecks occur? And what are the demand charges? All these aspects will need to be managed on a real-time basis, and will only be possible if the automotive industry, power generators, and network operators work together.