Have you ever considered using the electricity stored in your electric vehicle to power your TV or kettle? It might seem a bit futuristic, but this technology, known as bidirectional charging, is already available today. Bidirectional charging allows EVs to receive power from the grid and send power back. This means that EVs can act as mobile power storage units that can feed energy back into the grid – for example, during peak demand times.
What is bidirectional charging all about?
Although development has been rapid, today, it’s almost impossible to imagine our roads without electric cars. As more and more car manufacturers are shifting their business to e-mobility, it’s safe to say that this evolution will not stop. However, as EVs gain popularity, the question of charging options has become more important. Although there is definitely room for improvement, many European countries already have an extensive network of public charging points and stations, and owners can charge their cars at home safely using a charging unit.
And now, bidirectional charging is emerging as the next big innovation in the field. To make this possible, the electricity from the power grid, which is alternating current (AC), must first be converted into direct current (DC), a process that can be accomplished through a rectifier in either the car or the charging unit. If the car’s battery is used to power a household, the DC must then be converted back into AC, which requires special technology available in some charging units, such as our very own Zaptec Pro. Bidirectional charging has the potential to revolutionise how we think about the distribution of electricity.
What are the advantages and disadvantages of bidirectional charging?
For those who rely on renewable energy sources, such as solar power, bidirectional charging can be particularly beneficial. By storing excess energy in the car’s battery, you can use it to power your home or even feed it back into the grid, enabling energy self-sufficiency. This technology benefits not only individuals but the entire society because the use of more green energy will lead to a reduction in the consumption of fossil fuels.
In countries where time-of-day electricity rates are common, bidirectional charging stations can also help reduce costs. Charging your electric car overnight can result in lower electricity rates, and the stored energy can be used during peak hours, making electricity consumption cheaper. In addition, those who don’t use the excess energy stored in the car can sell it back to the grid, providing an additional source of income.
However, there are also some downsides to bidirectional charging. One of the disadvantages is that the frequent charging and discharging of the car’s battery can reduce its lifespan, potentially resulting in the need for an earlier replacement. Additionally, bidirectional charging stations are usually a bit more expensive than traditional charging stations. Despite these drawbacks, the benefits of bidirectional charging are significant, and its adoption is expected to continue to grow in the coming years.
What is the difference between this and intelligent charging?
Bidirectional charging refers to the flow between the car and the grid, while intelligent charging – or smart charging – refers to the possibility of controlling the charging time and speed using a smart device, which works on both uni-directional or bidirectional charging.
Here’s how the charging technology comes into play:
Electric vehicles that have the bidirectional charging option allow energy stored in the car to be used in three ways:
- Vehicle-to-home (V2H): The stored electricity can be used to supply power to the grid in the owner’s home, but a special charging unit equipped with a DC-to-AC converter is needed. Only a few manufacturers offer this option, and our Zaptec Pro charger is one of those.
- Vehicle-to-grid (V2G): With this option, the energy is returned to the public power grid, making electric cars useful as decentralized energy storage units. Since EVs, on average, are parked 90% of the time, they can be charged during off-peak hours, and the energy is returned during peak times, helping to relieve the pressure on the local and regional power grid.
- Vehicle-to-load (V2L), also known as vehicle-to-device (V2D): This option allows electrical devices to be charged while on the go by plugging them into the socket inside the car. Although not new, it is a very practical option.
What does the future hold for bidirectional charging?
Experts in the automotive and energy industries believe that bidirectional charging is the future of charging technology, offering great potential for more efficient use of stored energy. This is particularly true for its use in Vehicle-to-Home (V2H) charging, which has the potential to reduce the use of fossil fuels if the electricity is generated from renewable energy sources. Bidirectional charging can also positively affect the grid through Vehicle-to-Grid (V2G) charging, especially when solar and wind energy may not be available in constant quantities.
Japan has been utilizing the technology of bidirectional charging for several years following the nuclear disaster in Fukushima in 2011, resulting in a third of the country’s conventional power supply being lost. The country quickly adopted the technology in response, highlighting the potential for electric car batteries to act as ideal storage units for electricity.
However, in several European countries, there are challenges to the establishment of bidirectional charging, particularly related to legislation. While there are already individual vehicles with bidirectional charging functions on the market, widespread adoption of V2G charging faces questions, among them electricity prices, tax law, and data protection. This needs to be addressed going forward. Additionally, the charging infrastructure would need to be expanded considerably to support bidirectional charging at a large scale and at the vehicle-to-grid level.
As a result, experts predict that bidirectional charging on a large scale will likely not become standard until 2025 to 2030 at the earliest. Despite these challenges, the technology offers great promise for the future of sustainable energy.
Which cars can be charged bi-directionally?
For an electric car to be able to charge bidirectionally, it must have a CHAdeMO plug. In the future, however, a CSS plug will also be possible. The following e-car models are currently available on the European market (as of December 2022):
- Nissan Leaf
- Nissan e NV-200
- Polestar 3
- Honda e
- KIA EV6
- Hyundai Ioniq 5
- MG 5
- VW ID.3
- VW ID.4
- VW ID.5
- VW ID. Buzz
Is bidirectional charging allowed by law?
Individual private households are already using bidirectional charging technology. To expand bidirectional charging to V2G level, various ambiguities, such as questions about electricity prices, tax law or data protection, still need to be regulated and framework conditions established.