What Is Two-Way Charging – An Essential Guide

Owning an electric vehicle allows you to live a greener lifestyle. With bi-directional or two-way charging, you will earn more from your electric vehicle, among other fantastic benefits.

What is Two Way Charging? If you are not sure about bi-directional charging, this article will give you enough information to make up your mind. This article is your ultimate guide, providing a comprehensive background on bi-directional charging and how it can work for you.

We’ve also included the benefits of two-way charging and how it promises better EV charging in the future.

What is Two Way or Bidirectional Charging?

Bidirectional or Two Way EV charging is just as its name implies: an EV charging method that goes in two ways. While one-way or unidirectional EV chargers send electricity into the electric vehicle from the power grid, the electricity flows both ways with bidirectional EV charging.

Two-way charging enables:

  • the charging of cars with bidirectional charging and;
  • The taking of energy contained in car batteries and sending it back towards the power grid to balance increases in electricity demand.

Vehicle-to-grid (V2G) technology powers bidirectional charging. V2G enables owners to be in sync with the power supply and helps preserve the power grid amidst the demand responses.

How Does Bidirectional Charging Work?

Once an electric vehicle is charged, alternating current (AC) electricity that comes from the grid will be converted into direct current (DC), which can be used by the car. Such conversion is done by either a converter from the charger or the vehicle’s own converter.

If you want to use the energy within the electric vehicle’s battery for a property and put it back on the grid, the DC or direct current electricity in the vehicle will be converted into AC electricity again. 

Although presently there are not a lot of two-way EV chargers, all have internal converters. Thus, all of them can convert DC to AC and vice versa. They can also control the amount of power that’s being supplied towards the battery and reverse.

cars with bidirectional charging
Person plugging a charger to his EV

Are V2G and Bidirectional Charging The Same?

Not really.

Vehicle-to-grid and Bidirectional EV charging may be used synonymously but there’s a slight technical difference between the two.

  • V2G charging technology enables the one-way discharge of electricity from a car battery to the grid (vehicle to grid)
  • Bidirectional charging entails two-way charging (charge and discharge)

Nevertheless, V2G technology makes bidirectional charging feasible, and it’s hard to distinguish between the two if you’re using both interchangeably.

What Is the Difference Between Bidirectional Charging and Smart Charging?

Smart charging refers to any kind of EV charging (uni or bidirectional) in which the charging time and rate can be controlled by a “smart” device, rather than a manual on/off switch. This is done using data connections between the EV and the charger. 

Consider Smart EV charging apps, for instance, which allow you to control how long your EV is charged by using your smartphone. With smart charging, cars can be plugged in but they don’t have to be charging the whole time. 

Instead, individual EV owners or energy companies can decide when it’s most efficient to charge energy in terms of demand and cost, depending on the country and the energy operator. This can sometimes bring economic benefits for customers. 

For instance, many energy companies may offer preferential rates for night-charging. This also helps avoid situations in which a large proportion of EV owners charge at the same time, overloading the energy supply grid.

What Is Bidirectional or “Two-way” Charging Used For?

Bidirectional charging allows energy to flow both ways – in and out of your car. But where exactly does the energy go when it’s flowing out of your car?

  1. Vehicle to Grid (V2G)

Vehicle-to-grid occurs when bidirectional electric vehicle chargers supply power from the EV’s battery towards the grid with a DC-AC converter system embedded within the charger. Vehicle-to-grid can be utilized to settle and balance, energy needs through smart charging.

It enables electric vehicles to charge in off-peak hours and supply energy back to the grid during peak hours when there’s high energy demand. This makes a lot of sense as cars are just 95% of the time. With the right infrastructure and proper planning, plugged-in or parked EVs could serve as power banks to stabilize the electric grids.

We can treat EVs like big batteries that help ensure there’s enough energy for everybody at any time.

  1. Vehicle to Home (V2H)

Vehicle to home is a bidirectional EV charger used to transport power from an EV battery towards the house or another building. This is carried out using a DC-to-AC converter system that’s generally embedded inside the charger.

Just like V2G, this charging system helps settle and balance large-scale supply girds from local to national.

For example, by charging your EV overnight, there’s less demand for electricity and by using that power for your home in the daytime, you can help reduce consumption during peak hours where the demand puts a lot of pressure on the grid. V2H helps ensure your house has enough power when needed.

This reduces the pressure due to demand on the electric grid. Both V2H and V2G will play a crucial role as we head towards a completely renewable energy system. The reason for this is that different renewable energy sources produce various energy amounts depending on the time and season.

For example, solar panels capture most energy during the daytime while wind turbines during windy days, etc. Through bidirectional charging, the EV battery storage’s full capacity can be used to benefit the whole energy system and the planet.

Thus, EVs can be used as renewable sources for capturing, storing and supplying solar and wind power when the demand for it is high, or when the production of energy is low.

  1. Vehicle to Load (V2L)

V2L or Vehidle-to-load technology is simpler and doesn’t need a bidirectional charger to work. Vehicles that have V2L already come with standard plug-in AC power or a built-in bidirectional charger that is used to plug in any ordinary household AC appliances.

During emergencies, extension cords will extend from the vehicle into the property to power crucial loads such as lighting, fridges, computer, and cooking appliance.

bidirectional ev charging
EV being charged

V2L For Backup and Off-grid Power

While EVs with V2L are quite useful as backup power sources with extensions leading to power appliances, you can also connect the V2L power supply straight to the backup switchboard or the major distribution board with a specialised transfer switch.

A car with a V2L can adhere to an off-grid power supply to eliminate or reduce the necessity for a backup generator. The majority of off-grid solar power systems have bidirectional inverter chargers that enable them to tap into any AC source including vehicles with V2L.

But do this safely such that there is no need for a qualified electrician or specialist to install and configure it. 

Bidirectional Chargers

At present, the Wallbox Quasar and Highbury are the only two universal bidirectional DC chargers for home use (level 2); both are of the DC variety and work with the CHAdeMO (DC), while the recently announced Wallbox Quasar 2 works with the more common CCS-DC vehicle charge port. 

ev hooked up to a charging unit

Benefits of Bidirectional Charging

  1. Making Money While Giving Back to the Grid

As an electric vehicle owner, having a TESLA bidirectional EV charger will enable you to earn money from your vehicle by selling extra energy from your battery to the grid. The energy that’s stored or collected within your car’s battery can be sold back to the girl, even if it comes from your own sources like your home’s solar panels, renewable load, home power source or local market charger.

Countries where energy prices vary during the day, like Spain, or where the companies provide off-peak charging tariffs like the UK, enable electric car owners like you to save more money by providing more affordable charging at off-peak hours and selling energy to the grid during peak hours.

Studies reveal that potential income from an EV through V2G estimates go at €400 per year. Throughout an EV’s lifespan, the average potential V2G revenue is around €3700.

You can make even more money if you’re in the frequency regulation market. For instance, Nuuver Corporation is presently using 30 EVs in Denmark’s regulation market and estimates an earning potential of €9,000 throughout the car’s lifetime.

  1. Saving Money

Right now, owning an electric vehicle is significantly more affordable than owning a fossil-fueled car. Using a bidirectional charger will enable you to save even more money if you’re in a country where the energy costs change during the day. In Spain, for instance, you can charge your car at night time when the demand for electricity is low, allowing you to pay less during peak hours.

Besides this, a lot of national governments and energy companies are providing incentives or price cuts to electric vehicle drivers so they can charge during off-peak hours when electricity is cheaper.

Thus, some energy companies are now providing differential off-peak energy tariffs to electric car owners where you pay the usual price during daytime, but more affordable rates at certain hours during night time.

This helps balance the grid and ensures that not all electric vehicles are at times when there’s high demand. If you can use such electricity inside your electric vehicle to power your house in the daytime, you can enjoy much cheaper energy than you normally would at such hours. As a result, you can significantly save more on your electricity bills.

  1. Becoming Energy Self-Sufficient

Bidirectional electric vehicle charging can provide you with the chance to be energy self-sufficient should you mix it with renewable energy sources. If you install solar panels on your roof to provide power to the house in the daytime, the extra energy can be reserved within your vehicle and used at night time, or the following day while you’re driving.

Some countries introduce incentives and programs to aid individuals in doing this. For instance, the DSR or demand-side response scheme within the United Kingdom offers smart meters to homeowners and encourages them to produce their energy through onsite renewables such as solar photovoltaic and wind.

It also enables them to send extra energy back to the grid. With the aid of these schemes and other incentives in Europe, your home could become a micro-power station shortly.

The principal works not just in single homes but also in big apartment blocks and communities. While charging in apartment blocks has been considered troublesome for several reasons, energy self-sufficiency can help solve this problem by providing energy to residents in a very centralized system.

For instance, schemes like the Brooklyn Microgrid, a New York-based energy marketplace for renewable, local, resident-produced energy. Indeed, others that seek to produce energy as a community could well use EVs to capture, store, and sell back energy to their microgrid. 

In this way, bidirectional charging could be a potentially crucial part of community-led renewable energy generation schemes that seek communitarian energy resources within a self-sufficient community, not just one household.

Electric Vehicles and Bidirectional Charging for Mobile Storage

Bidirectional electric vehicles used as mobile battery storage add demand-response and resilience benefits to the site’s infrastructure. Bidirectional electric vehicles can acquire energy from EVSE or electric vehicle supply equipment and supply energy to a discharge when paired with a similar EVSE.

Bidirectional cars can supply backup power to specific loads or buildings, sometimes as microgrids, through V2B for vehicle-to-building charging, or supply power to the grid through V2G or V2G.

V2G and V2B power systems can sync with PV or solar photovoltaic arrays and other DERs or distributed energy sources, or supplementary diesel generators for backup power. Unlike stationary generation and storage which stays at a selected site, bidirectional electric vehicles as mobile storage are mobilized to the site before a planned outage or arrive shortly after an unexpected power outage to generate or reserve emergency power.

A light-duty electric vehicle battery size makes a bidirectional unit fantastic for smaller applications such as buildings where they’re optimized for PV use and serve as emergency generators. Bigger bidirectional EVs can be used for bigger applications.

Equipment needs and costs vary according to the site’s location, design, size and more. While planning an EV infrastructure, sites must consider the present capacity since some infrastructure may be available like inverters for solar PVs or transfer switches for an emergency generator.

bidirectional ev charger cost
EV charging

Bidirectional EVs Increase Resilience

Mobile batteries increase an infrastructure resilience posture during decarbonizing emergency generation. The use of EVs for mobile storage reserves the energy amount the site can use from the grid or help reach carbon emission targets by maximizing local sustainable energy generation and consumption. 

Aside from that, regional fleets are deployed to specific locations during emergencies, giving electric vehicles an edge over stationary batteries.

Bidirectional Electric Vehicles for Demand Response

While planning for your fleet and site’s energy needs, bidirectional EV fleets can take part in the time of use or demand response cartilage. Several utilities offer grid service wherein devices like EVSE can be controlled during peak hours on the grid to reduce energy costs and lessen its burden on the infrastructure.

Grid service markets implement frequency regulations to balance the demand and supply of power. Such benefits provided through the TOU rates are generally designed with on-off peak rates.

EVSE that can shift EV charging to take place during off-peak rates can decrease the fleet’s electricity costs. Taking part in grid services like these can help save money for your facility and reduce power shortages during peak hours.

Working With The Utility Company

Agencies must work with the electric company in the planning and electrification procedure to minimize the costs through a good understanding of rate structure and provision of incentives for the site.

Coordinating with your utility before installing EVSE will help ensure that your site can save more money and take part in the regulation of the site’s electricity load with the grid’s availability. Installation involves planning from the fleet operator and utility in advance.

To some organisations, this may mean changing the timeliness and business procedures.

Vehicle to Building Charging

Several V2B applications can decrease grid electricity costs with TOU arbitrage or increase local generation value by consuming on-site energy or preventing PV curtailment. A lot of the applications focus on site resiliency like using backup generation or microgrid to support site loads during an outage.

Due to the high failure rates of emergency generators, the new focus is now on carbon pollution-free electricity (CFE), stationary storage and DERs. Bidirectional charging makes EV batteries more resilient and provides demand-response capacities while decarbonizing backup power.

Bidirectional Charging is The Future

With the majority of electric vehicles parking at home or work all day and night, you may ask whether it’s worth it. But what if there are big batteries in cars that can help you earn some money?

Surplus energy from EVs can be sold back into the grid and this can power millions of homes when it’s most needed, which is quite significant with the global energy crisis. With vans and cars parked 23 hours a day on average, the potential is quite great.

By the year 2030, while no new petrol and diesel vehicles are allowed for sale in the UK, it is projected that 84 million EVs will hit the roads across Europe and 14 million on the British roads, as estimated by Delta-EE energy consultancy. That’s a lot of batteries on cars.

Thus, all that people really need is a charger that works either way. Bidirectional chargers enable users to store affordable solar-generated or off-peak electricity or solar electricity inside a car battery and export it directly into the grid or house when electricity costs much.

But there are a number of obstacles to beat before users can accept bidirectional charging and it can go mainstream.

Several energy companies are trying to make bidirectional charging work commercially. There are at least 100 V2G trials throughout the world, and the majority of them are in Europe collaborating with charger and electric vehicle manufacturers and grid providers. 

TESLA bidirectional charging
Modern home with a charging unit for electric vehicles

Bidirectional chargers are projected to be cheaper within the next few years as more infrastructure is developed and they become more common. But EV owners must still be convinced of the need to charge and discharge faster without degrading their batteries.

The thought of lower electricity bills and bidirectional charging will more likely help encourage people to purchase an electric vehicle.


Bidirectional charging enables electricity to flow in and out of electric vehicles and the technology will only advance as the years go by. As the technology advances, so will its potential. As an EV owner, you will surely benefit from a bidirectional charger. 

From saving money to making extra money selling energy to the grid and becoming more energy-sufficient, going bidirectional will surely pay off. For what it’s worth, it will future-proof you and your business.

Expand your knowledge: Explore additional resources and recommended readings to gain a broader understanding of Two-way EV Charging


  • Jasmine Cross

    Jasmine Cross is a passionate advocate for sustainable transportation solutions and an avid enthusiast of electric vehicles (EVs). With a background in environmental science and a keen interest in renewable energy technologies, Jasmine brings a wealth of knowledge and a fresh perspective to the world of EV charging.

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