An EV home charger is perfect for keeping your electric car powered up, but is the garage the best place to put it? Let’s look at the options.
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Guide to bidirectional charging in Australia
Bidirectional charging technology enables electric vehicle owners to use their car to power their home. Here's how it works.
Electric vehicles are gaining traction in Australia as car buyers weigh up running costs, pricing, rebates, charging infrastructure, driving range and unique EV-only features. But what if we told you could use an EV to power your house? Or that you could maybe make some money by selling power from your vehicle’s battery back to the grid?
Welcome to the emerging world of bidirectional charging. But what is bidirectional charging and how does it work with an electric vehicle?
Bidirectional charging explained
What is bidirectional charging?
A vehicle with bidirectional charging capability – also known as vehicle-to-grid (V2G) or vehicle-to-home (V2H) charging – can not only take power from the grid to charge the EV battery, it can also supply power back to the grid, or power a home, using energy from the EV battery. Effectively it enables your electric vehicle to act as a home battery, storing energy that can be used to power your home or sold to the grid.
How does bidirectional charging work?
To charge a conventional EV, you need a unidirectional charger to convert AC (alternating current) electricity sourced from the grid to DC (direct current) electricity. This is done by a converter, either built into the vehicle, or housed in the charger. If you want to use the energy stored in the EV’s battery to power your home or send it back to the grid, the DC electricity from the car must be converted back to AC electricity. That’s done by a bidirectional charger, which looks similar to a regular home EV charger.
Bidirectional charging is already being trialled overseas in the United States, United Kingdom and Denmark and has been used to power houses, office buildings and even to power tools in the aftermath of several natural disasters in Japan. Nissan says the 62kWh battery in the Leaf e+ can store enough energy to power an average Japanese home for up to four days.
Is bidirectional V2G charging available in Australia?
Not yet, but a trial backed by the Australian Renewable Energy Agency (ARENA) was carried out in Canberra between June 2020 and March 2023 to test the technology in a local market. The Realising Electric Vehicles-to-grid Services (REVS) trial involved 51 Nissan Leaf EVs from the ACT Government fleet that when plugged in fed power back into the grid.
According to JetCharge, a leading supplier and installer of EV charging infrastructure, the only Australian jurisdiction that has approved V2G bidirectional chargers for install and use is South Australia. But even there getting a bidirectional charger is easier said than done. Australia's only certified bidirectional charger, the Wallbox Quasar 1, was released in limited numbers in early 2022 and has ceased being available for retail while the company works on the Quasar 2.
What is vehicle-to-load (V2L) charging?
EVs with bidirectional charging capabilities can also be used to power appliances without interacting with the power grid or your home electricity network. Vehicles with vehicle-to-load (V2L) charging enabled will either have a standard powerplug built into the car or a have a V2L adaptor that can be used with the car's charging port. For example, this functionality may be helpful if you're going camping and simply can't do without certain modern appliances, as well as in the case of a power outage or if your laptop dies while on the road for work. V2L charging is also already available in Australia in cars like the Hyundai Ioniq 6, Hyundai Ioniq 5 and the Kia EV6.
Are all EVs capable of bidirectional charging?
Currently vehicles with a CHAdeMO charge port can facilitate bidirectional charging. In Australia, that is limited to the Nissan Leaf EV, Mitsubishi Eclipse Cross and the Mitsubishi Outlander PHEV.
Ishan Jagaty, Technical Training Team Leader and Electrical Engineer at JetCharge, says that more cars will have bidirectional charging in the near future thanks to a industry-wide change in charging ports. "Moving forward, CCS2 V2G is set to become the standard in Australia, and vehicle manufacturers will be required to incorporate V2G technology into their cars," he says.
"The period from 2024 to 2025 promises to be an exciting time for this space, as standards, vehicles, and chargers converge. While there are numerous challenges, the distributed energy resources (DER) sector shows promising prospects."
Electric cars with bidirectional charging capability can supply power back to the grid, or power a home, using energy from the EV battery. Image: Supplied
How much will a bidirectional charging unit cost?
The Wallbox Quasar 1 retailed for around $10,000 AUD but no official price has yet been announced for the Quasar 2. More chargers are expected to hit the market by 2030 according to the REVS project, with the price of chargers also expected to drop and for some EVs to even have V2G capabilities fully integrated within the vehicle.
"Presently, the installation of these chargers is relatively expensive due to additional protection requirements," Jagaty says. "However, as mass market adoption increases, we can expect the prices to come down."
Can bidirectional charging save me money?
A car with bidirectional charging capability effectively acts as a home battery enabling you to store excess energy that can then be used to power your home or sold back to the grid. If that energy used to charge the car comes from a free or cheap source, such as rooftop solar, a free charger at your local shopping centre, or even your workplace, there’s the potential to reduce your home energy bills. Alternatively, you may be able to sell electricity back to the grid, charging your car off peak and selling back to the grid during peak afternoon and evening hours to optimise your financial return.
Will vehicle-to-home charging drain the EV’s battery?
Just like a battery bank, using bidirectional charging to power your home will deplete the electric vehicle's battery. With solar panels and a little forward thinking, however, you can balance your energy usage and ensure you've still got juice in the tank when you need it.
"The optimal scenario for vehicle-to-home usage is charging the car during the daytime when there is ample sunlight and surplus solar energy from the grid, whether you are at work or at home," Jagaty says. "This way, the car can discharge power during peak evening periods and recharge again during the off-peak evening periods."
Is bidirectional charging safe?
There are measures built into the chargers to mitigate any safety issues. Bidirectional chargers work in a similar way to solar inverters, and have a sensor to monitor the load of the house and how much power is being pumped in and out of the house. If the sensor detects that system voltage has been breached, the charger will switch off.
Will the car battery deteriorate faster if I use bidirectional charging?
"The impact of bidirectional charging on battery life can vary depending on the specific vehicle, battery chemistry, charging infrastructure, and usage patterns," says Jagaty. He notes that research and development is constantly ongoing to maximise battery performance while minimising any negative impacts on battery life.
It's recommended consumers contact the electric vehicle manufacturer or refer to their specific vehicle documentation to find out more about how bidirectional charging could affect battery life.
