Bi-directional EV charging is an emerging technology that is poised to help shape the future of transportation and sustainable access to energy, potentially revolutionizing how most people think about their electricity.
In this guide, we’ll introduce bi-directional EV chargers, explain how they work, showcase the technology's benefits, and share why any homeowner with an electric vehicle and a solar-powered home should consider one.
What is a bi-directional EV charger?
A bi-directional electric vehicle (EV) charger is a system that allows electric vehicles to not only receive power from your home or the grid, but also send excess power back to your home or the grid. It enables two-way communication between an EV and the electrical grid, allowing energy to flow both ways.
Compared to traditional or “mono-directional” chargers that can only send power to a battery, a bidirectional charger allows EV owners to discharge electricity from their vehicle to use onsite, share, or sell.
By definition, bidirectional EV chargers can refer to any product that is able to transmit electricity in two directions: into and out of an electric vehicle battery. As an exciting new piece of electric vehicle supply equipment (EVSE), bi-directional EV chargers are expected to become widely available in the mid-2020s.
How does bi-directional EV charging work?
Bi-directional EV charging works in several different ways, with various capabilities that can benefit homeowners, travelers, businesses, the energy grid, and communities recovering from natural disasters.
Vehicle-to-Home (V2H) & Vehicle-to-Building (V2B) Charging
Vehicle-to-home (V2H) charging is the process of powering the electric load of your home with energy transmitted from an EV battery. Also known as vehicle-to-building (V2B) charging in larger instances, V2H charging allows bi-directional EVs to function as a backup generator that provides backup power to run lights, electronics, and appliances onsite.
Whether the energy grid has a temporary power outage due to severe weather conditions, or utility rates are at their highest due to local demand, V2B and V2H chargers can enable you to pivot away from grid-supplied electricity and power your property with your vehicle’s battery reserve.
Of course, just because you can power your home with your car does not mean it has to remain in the driveway. After all, electric vehicles are still vehicles, meaning that bidirectional charging can transform capable EVs into mobile storage batteries.
With dozens (and potentially hundreds) of kilowatt-hours available on the go, bi-directional EVs can use V2H or V2B charging to power any property within driving distance.
With the proper equipment and local utility agreements, bi-directional EV chargers may be used as “vehicle-to-grid chargers” (V2G). With V2G charging, power is exported from your EV’s battery reserve and sent to a third party through the electricity grid.
By sending electricity from an EV to another person, exporters may be compensated for the energy they share or sell, depending on the rules and regulations enforced by local utilities. Although the infrastructure for V2G charging is still in its infancy in 2023, V2G charging has enormous implications for future energy markets if EV owners can sell their battery power easily and profitably.
Sometimes, you may not even need a home or building to use your EV’s energy! Some vehicles have bi-directional charging capability built in that allows you to directly power home appliances, camping equipment, mobile workstations, large electronic devices, power tools, and more.
Unlike V2H and V2G charging, V2L does not require a bi-directional charger, as the EV uses an integrated inverter to send AC power directly to the device.
While the early iterations of bi-directional charging are designed to work with either your home, the grid, or a specific electric load, many manufacturers are looking to adapt their bi-directional charging systems to work with anything, integrating all of the bidirectional charging types into a single vehicle as needed.
Benefits of Bi-Directional Charging
With vehicle-to-grid and vehicle-to-home technology, bi-directional EV charging delivers many financial and lifestyle benefits for homeowners and their communities.
Energy Resilience, Mobile Power Storage
Energy resilience is perhaps the most important benefit of bi-directional EV chargers, allowing electric vehicles to act as mobile batteries. With a backup source of electricity on wheels, bi-directional charging can help keep homes online during blackouts, or deliver fleets of power to areas in crisis after forest fires, hurricanes, or other disastrous events.
Utility Demand Response & Grid Stabilization
Even if there is not an emergency, bi-directional EV chargers can help stabilize the supply and demand of the power grid for utilities serving communities on a daily basis.
To increase the energy supply during peak demand hours, electricity companies can incentivize EV owners to discharge their battery power in exchange for bill credits or real cash compensation.
Optimized Charging Costs and Energy Savings
While managing the flow of electricity between your home, vehicle, and the grid, bi-directional EV chargers can help optimize your total ongoing energy costs. Especially when connected to a home solar energy system, bi-directional chargers make it easy to power your life with the cheapest possible electricity source.
For example, when you charge your EV with the excess energy produced by your solar panels each day, you could then run your vehicle with the free and infinite power of the sun, export the clean electricity to your home, or send it to the power grid.
What EVs have bi-directional charging?
While the technology itself is slowly being developed and rolled out to customers, only some electric vehicles on the market today can support bi-directional EV charging. In 2023, there are several cars with bidirectional EV charging capabilities built-in, including the Nissan Leaf, Kia EV6, Ford F-150 Lightning, Hyundai Ioniq 5, and more.
Notably absent from this list is Tesla, as the Tesla Model S, Model 3, Model X, and Model Y currently do not support bi-directional charging.
In summary, bi-directional charging enables electric vehicles to act as mobile power generators that can be used to electrify homes, buildings, and more.
With vehicle-to-home and vehicle-to-grid charging, EV drivers can utilize bi-directional chargers to share their energy with others, or temporarily power their own lives in the absence of utility-supplied power.
Given these potential benefits, the technology may have huge implications for the rapid revolution of electrified transportation, energy management, and sustainable energy infrastructure in the near future.