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."