Unlocking Additional Benefits of Electric Vehicles: Bidirectional Charging
Fleets worldwide are adopting electric vehicles (EVs) to lower costs, reduce pollution and greenhouse gas emissions, comply with low-emissions regulations, and take advantage of benefits like instant torque and quiet operation. However, one advantage of EVs that’s often overlooked is their ability to export power, a feature known as bidirectional charging.
EV bidirectional charging allows vehicles to become a flexible load and a power resource, unlocking a range of valuable applications. Unlike traditional unidirectional charging, bidirectional-capable EVs allow for a two-way flow of energy. While not all EVs have this capability, it is becoming increasingly available in new models.
What is bidirectional charging?
Bidirectional charging is a process that allows bidirectional-capable EVs to export energy from their main battery to power other EVs, electrical devices, homes and buildings, and microgrids— or even sell energy back to utilities
Bidirectional Charging: Key Terminology to Understand
Bidirectional charging is a process that allows a bidirectional-capable electric vehicle to export the energy stored in its main battery for various applications. This capability, often referred to as Vehicle-to-Everything (V2X), encompasses several key applications:
Vehicle-to-Vehicle (V2V): Enables an EV to recharge another EV’s battery.
Vehicle-to-Load (V2L): Powers tools, appliances, or other loads using an EV.
Vehicle-to-Home/Vehicle-to-Building (V2H/V2B): Supplies supplementary power to a home or building, operating behind the meter. It can be grid-connected or not.
Vehicle-to-Microgrid (V2M): Powers multiple buildings, such as campuses or community centers, as part of a microgrid.
Vehicle-to-Grid (V2G): Sends power directly to the electrical grid or indirectly supports grid-connected loads.
System Categorization
Bidirectional systems can be either energized (off-grid) or interconnected (grid-connected):
Energized Systems: Power loads that are not connected to the electrical grid, such as in V2V, V2L, or isolated V2H/V2B/V2M systems.
Interconnected Systems: Used with a utility interconnection agreement to power loads that are connected to the grid. When grid tied, V2H, V2B, V2M, and V2G are interconnected bidirectional systems.
Fleet Benefits of Bidirectional Charging Systems
Bidirectional charging enables fleets to unlock new operational efficiencies and enhance their energy resiliency. Below are some of the unique benefits of each bidirectional charging application.
Vehicle-to-Vehicle (V2V): Charging Other EVs
With V2V systems, fleet bidirectional-capable EVs can recharge other EVs, including plug-in hybrid electric vehicles (PHEVs). Each fleet can decide whether to recharge only vehicles within their fleet or also extend this capability to other fleets or individuals. Benefits include:
Providing EV charging in remote locations where grid-tied chargers are unavailable.
Avoiding costs and delays associated with towing depleted EVs.
Providing EV charging during disaster response or grid outages.
Vehicle-to-Load (V2L): Powering Equipment and Devices
V2L systems enable EVs to serve as mobile power sources, powering tools and appliances without relying on grid-tied electricity or portable generators/batteries. Some of the benefits include:
Providing electricity during outages, in off-grid locations, or during emergencies or natural disasters. EVs can power medical equipment, communication devices, emergency relief tools, cooking appliances, water purification systems, and more. For instance, during the 2021 Texas power outage caused by Winter Storm Uri, many EV owners unexpectedly found their EVs to be lifelines, providing heating and power for various essential devices.
Powering a host of tools, equipment, and devices at job sites without power or that would otherwise rely on portable generators.
Reducing costs and time by eliminating the need to rent or maintain portable diesel or gas generators for temporary energy needs while also reducing noise, onsite air pollution, and greenhouse gas emissions.
Supporting the transition from diesel/gas-powered tools to electric alternatives, reducing fuel costs, maintenance, noise, and emissions.
Vehicle-to-Home/Building (V2H/V2B): Supporting Infrastructure
Bidirectional-capable EVs can supply power to homes or buildings as energized systems (operating off-grid) or interconnected systems (grid-tied with utility approval). This will require bidirectional-capable EVSE, home/building panel upgrades, and a utility interconnection agreement. Some of the benefits are:
Reducing peak demand charges by powering loads during periods of high electricity costs or carbon intensity.
Providing backup power during outages or blackouts.
Engaging in Time-of-Use (TOU) arbitrage, recharging EVs during low-cost periods and powering loads during high-cost periods.
As an example of TOU arbitrage, consider the North Boulder Recreation Center in Boulder, Colorado. The organization piloted a program using a Nissan Leaf and a Fermata Energy bidirectional charger to reduce the building’s peak demand. The Leaf charged during off-peak hours and supplied electricity during peak times, cutting grid demand and saving almost $250/month— enough to cover most of its lease payments. The vehicle remained available to staff as needed, with no impact on operations.
Vehicle-to-Microgrid (V2M): Enhancing Microgrid Resilience
V2M systems integrate EVs into microgrids, providing backup power for critical sites such as campuses, community centers, or military bases. These systems often require a microgrid controller in addition to bidirectional-capable EVSE. Key benefits include:
Enhancing resilience by allowing EVs to move between different sites within a microgrid and supply power where it’s most needed.
Integrating with renewable energy sources such as solar and wind, or stationary battery systems to enhance system efficiency and reliability.
Vehicle-to-Grid (V2G): Supporting Grid Operations
V2G systems allow EVs to discharge power back to the grid in parallel with grid operations, functioning as an interconnected system. These systems require utility approval, interconnection studies, and agreements, making them more complex than other bidirectional systems. Some of its benefits are:
Providing grid services like energy arbitrage, frequency regulation, and localized voltage support. When aggregated, EVs can function as virtual power plants (VPPs). For example, ev.energy, community choice aggregator MCE, and Silicon Valley Clean Energy (SVCE) are developing ChargeWise, a 300MW VPP aiming to enroll 275,000 EV drivers by 2027.
Enhancing grid reliability by offering a flexible power resource during periods of high demand or instability.
Generating revenue through participation in grid services programs, if available, through their local utility.
Final Considerations for Harnessing Bidirectional Charging
The benefits of bidirectional charging systems are numerous, with varying levels of complexity. Since vehicles primarily move people and cargo, the remaining energy available for bidirectional charging will be limited. Fleets may start with simpler systems, such as V2V or V2L, before progressing to more complex systems, such as V2B or V2G.
Ready to explore the benefits of bidirectional charging for your fleet? Sawatch Labs, a WEX Company, provides expert guidance on EV integration and charging infrastructure optimization. Contact us today to discover how we can help you unlock the full potential of your electric fleet.