A Primer on Bidirectional Charging
Did you know that your electric car can also use the energy in its battery pack to power electrical devices, power your house in an emergency, or even sell electricity back to the grid? We take a look at an amazing benefit of owning an EV.
How EVs Can Support the Electrical Grid
When we typically think about electric vehicles (EV), we look at them as cleaner and more efficient replacements for our current internal combustion engine (ICE) vehicles used to shuttle us from point A to B.
Millions of North Americans have happily opted to replace their ICE vehicles with EVs. But some are concerned about whether the electrical grid can support the charging requirements of a growing number of EVs. With the average American home using about 30kWh of electricity per day, adding EV charging to the mix could potentially put further strain on the grid.
However, if you look at the bigger picture with EVs and beyond their vehicle capabilities, they’re actually mobile battery packs with stored electricity. This enables them to become part of the overall electrical ecosystem, especially when the vehicles are parked for the majority of the day.
Bidirectional charging is an emerging technology that enables EVs to utilize the electrical energy stored within their battery packs to power a variety of electrical devices, your home, or even send electricity back to the grid.
What Is Bidirectional Charging?
Today, charging an EV is mostly a one way proposition. Using a Level 1 or Level 2 charging system at home, business, or at a public charger sends alternating current (AC) from the electrical grid to your EV. During the charging process the AC power is converted to direct current (DC) and stored in the EV’s battery. The EV then uses the DC power stored within the battery to run the vehicle.
Bidirectional charging simply allows the reverse of that process to happen. It takes the DC power from the EV’s battery pack and sends it back as AC power to an AC-powered device.
Types of Bidirectional Charging
As the technology evolves, you’ll likely see different types and references to bidirectional charging. The most common types of bidirectional charging are vehicle-to-load (V2L), vehicle-to-home (V2H), and vehicle-to-grid (V2G).
V2L is the most basic form of bidirectional charging. It is available today on some of the popular EVs. Using either an adapter or the vehicle’s built-in equipment, stored electricity from the EV’s battery can be used to power many 120-volt and 240-volt AC devices up to 9,600 W, depending on the vehicle.
V2H requires additional external equipment installed in your home or building but allows your EV to power your entire home for a certain amount of time. Think of your EV and its battery as a zero emission backup generator that can be used during power outages or even when electricity rates are high.
V2G enables your EV to not only power your home but also send electricity back to the grid and your utility company. This is similar to what some homeowners do with solar power in certain markets. It’s important to note that V2G technology is still being tested by various utilities, automakers, and organizations so it’s currently available in very limited markets.
You’ll also start seeing vehicle-to-vehicle (V2V) systems emerge, which allows one EV to charge another EV. Today, only a few EVs, such as the Ford F-150 Lightning and Lucid Air, are capable of V2V charging.
Vehicle-to-Everything (V2X) is a generic term that will become more common as bidirectional charging technology emerges, encompassing all types of bidirectional charging options.
Benefits of Bidirectional Charging
Although the technology is evolving, there are three main benefits of bidirectional charging.
Save on Energy Use: Turning your EV into a power source for your home or devices can help save you money on electricity. For example, you can charge your EV during off-peak hours and then power your home or devices during high peak times when electricity rates are more expensive. With V2G technology, you can potentially sell that energy back to the utility company. According to a study by the University of Rochester, V2G chargers could potentially save EV owners between $120 to $150 per year.
Store Backup Power for your Home: V2H technology allows your EV to become a backup power source, similar to today’s gas generators. With the right equipment, during power outages or natural disasters you can potentially use your EV to power your home for a few days in an emergency.
Create a Portable Power Source: When you’re on the road or even camping, you can use your EV as a power source for small appliances, like a coffee maker, electric stove top, lighting, or even a cooler. For example, the V2L adapter available on the Ioniq 5 can off-board power up to 3.6 kW (3,600 W), which is more than enough for many small appliances. The F-150 Lightning can off-board up to 9.6 kW (9,600 W), which is more than enough for many home appliances and job site AC power tools.
Which Vehicles Offer Bidirectional Charging?
Bidirectional charging is still in its infancy, so unfortunately not every EV today can currently support it. Additionally, not every EV can support the different types of bidirectional charging.
Many EVs today can support V2L. The newest EVs from Hyundai, Kia, and Genesis can support V2L through an adapter and run many 120-volt AC devices. Others, like the Mitsubishi Outlander PHEV, have a built-in 1500 W 120-volt outlet. New EV pickup trucks, like the Ford F-150 Lightning, Tesla Cybertruck, and Chevrolet Silverado, can off-board both 120-volt or 240-volt AC power through multiple outlets in the bed and front truck areas.
V2H and V2G capabilities are still emerging, so currently only a select few EVs can support this technology and require additional equipment to be installed. The Ford F-150 Lightning, as an example, can send power back to your home but requires the purchase and installation of the Ford Charge Station Pro bidirectional charger, an Intelligent Backup Power System, and Home Integration Kit for a fully integrated system.
GM’s newest EVs, like the GMC Denali EV, can also support V2H and V2G with the purchase and installation of the PowerShift bidirectional charger, V2H Enablement Bundle, and Home Hub. While the Ford and GM systems are fully integrated with your EV and home, the equipment can be costly at $5,000-7,000 USD. Installation can cost up to $15,000 or more depending on how complex it is for your home. As the technology improves and a wider range of automakers and companies get involved with V2H and V2G, those costs will likely come down. There may also be rebates from GM, Ford, or from your local utility company. It’s important to check with your local utility about whether V2G is supported.
BMW, Ford, Honda, and Nissan, have formed an independent company, ChargeScape, to help create a single platform that will connect their future EVs with electric utilities to support V2G bidirectional charging. It uses an Open Vehicle-Grid Integration Platform (OVGIP) that enables utilities in North America to access battery energy and data from EVs linked to the grid. It can then reduce energy demand and charging during peak periods, as well as send an EV’s stored energy back to the grid.
It's always best to check with the auto manufacturer about what type of bidirectional charging your EV can support and the necessary equipment. Only use authorized adapters and equipment for your EV in order to avoid damaging your vehicle and voiding the battery warranty.
Bidirectional Charging: An Emerging but Promising Technology
Although bidirectional charging for EVs is still emerging, the benefits for consumers, cities, and utilities are clear.
Unlike gas-powered vehicles, the onboard and stored power of EVs can be used both to produce vehicle power while in motion or to provide external power while the vehicle is stationary. Bidirectional charging not only has the benefit of powering our devices and homes, it also has the larger potential to stabilize the electricity grid and reshape how we think about energy storage and grid reliability.
