The average electric vehicle (EV) battery stores approximately 60 kWh of energy – enough to power an average home for two days. America’s 2.4 million EVs represent approximately 147 GWh in storage capacity, or roughly five times the stationary battery storage currently on the grid. Although most EVs on the road today lack bidirectional charging capabilities, this amount of storage provides a largely untapped renewable and decentralized resource for power systems, which can be used as backup power during emergencies, for load balancing and flexibility during peak demand times, and more. These benefits will help defer costly grid upgrades and contribute to affordable rate structures.
The rapid growth in demand for electricity has grid operators racing to secure new generation assets. Virtual power plants (VPPs) are an innovative solution that utilities are beginning to embrace. VPPs aggregate the generation capacity of distributed energy resources (DERs), including solar panels, wind turbines, and home battery systems. While EVs can be a part of that mix, until recently, most models didn’t support bidirectional charging, and even fewer chargers were equipped for it. However, automakers, utilities, and regulators now recognize the potential of leveraging millions of EVs as a source for VPPs.
So, how much storage capacity are we talking about here? An ENREL study predicts EV batteries could provide a technical capacity of 32-62 TWh by 2050. Remarkably, even with vehicle participation rates as low as 12 to 43 percent, these batteries could meet the short-term storage needs for most of the world as early as 2030.
A recent study shows that bidirectional charging in Europe could save up to 22 billion euros annually by 2040. Another EU study found that bidirectional charging could save homeowners up to 780 euros per year on electricity bills, and a U.S. study found that it provides $150 in annual savings to participating EV owners. EVs could become Europe’s fourth-largest power supplier by 2040, instantaneously providing 15-20% of electricity demand during peak periods.
Bidirectional charging made its global debut with the 2013 Nissan Leaf. For over a decade, it remained a largely experimental concept relegated to a handful of vehicle models and pilot projects. That’s beginning to change. Tesla says all its vehicles will be capable of bidirectional charging in 2025, and GM says it will come standard across its EV lineup by 2026.
The future of EV charging is clearly a two-way street.
How Does Bidirectional Charging Work?
Bidirectional charging enables power flow in both directions between an electric vehicle (EV), the grid, and other consumers. The concept of vehicle-to-everything (V2X) encompasses any scenario where the energy stored in EV batteries is dispatched to the grid, buildings, houses, and other energy consumers. V2X requires two-way energy flow between the charger and the vehicle, with bidirectional or one-way flow from the charger to the destination, depending on the specific use case:
- In vehicle-to-grid (V2G) charging, the power grid uses electricity stored in EV batteries as a supplementary source of energy to balance loads during high-demand periods.
- Vehicle-to-home (V2H) charging works like V2G but at a much smaller scale. The EV battery can provide electricity to the home for up to several days during power outages or store renewable energy generated on-site.
- Vehicle-to-vehicle (V2V) charging allows power flow between two or more EVs.
- Vehicle-to-load (V2L) uses a DC-to-AC inverter to power electric devices, equipment, and appliances.
Bidirectional charging is emerging as a valuable and largely untapped distributed energy resource (DER). In all V2X applications, the stationary EV battery functions as a peak-demand power plant. These batteries gradually accumulate energy during off-peak hours while parked and can be drawn upon almost instantly to discharge that energy when needed. V2X provides an efficient way to store affordable energy during periods of low demand (and low cost) or on sunny or windy days when renewable energy is abundant, and rapidly deliver it to the grid, a home, or other energy loads when required.
What is needed for bidirectional charging?
While not all EVs support bidirectional charging, a small but growing selection of models does. As of February 2025, V2X-capable EVs are being produced by Ford, Genesis, Volvo, GM, Hyundai, Kia, Mitsubishi, Nissan, VW, Polestar, BYD, MG, Renault, and Tesla and include the following models:
- Ford F-150 Lightning
- Chevrolet Silverado EV RST
- GMC Sierra EV Denali
- Chevrolet Blazer EV
- Chevrolet Equinox EV
- Cadillac LYRIQ
- Cadillac ESCALADE IQ
- Cadillac OPTIQ
- Genesis GV60
- Hyundai Ioniq 5
- Hyundai Ioniq 6
- Kia EV6
- Kia Niro
- Mitsubishi Outlander PHEV
- Nissan Leaf
- VW ID.4
- Polestar 3
- Tesla Cybertruck
- BYD Atto 3
- BYD Han EV
- MG ZS EV
- Renault 5
Bidirectional EVs require two-way chargers, such as the Wallbox Quasar or Rectifier Technologies’ Highbury, and others listed here.
In addition to compatible hardware, bidirectional charging systems need clear protocols dictating how the vehicle communicates with charging equipment, consumers, the grid, and third-party service providers.
ISO 15118, OCPP, and Smart Charging Software
ISO 15118 is the industry standard that defines the communication protocol between a charger and a vehicle and is what enables V2G capabilities. OCPP defines the communication protocol between charge ports and a backend system, enabling capabilities like charging session management, billing, remote monitoring, and more.
Together, ISO 15118 and OCPP provide a secure, standardized framework for EV charging, including the capability for Plug & Charge, the streamlined user experience in which simply plugging in automatically initiates a charging session without requiring additional user interaction. These standards facilitate the comprehensive management of charging stations, including bidirectional charging. Efficiently integrating these protocols and applying dynamic load response requires smart EV charging software, which optimizes the transfer of energy from all available sources to the various loads.
For example, when favorable weather conditions produce an abundance of renewable energy, smart charging software can deliver that power to EVs without compromising on delivering energy to other loads. Alternatively, during peak demand periods, smart charging software can throttle supply to EV charging to reduce demand on the grid. Note that with V2G capabilities, the vehicle can be both a source and a consumer of energy. In this way, smart charging software helps balance the grid by charging vehicles during energy surplus periods and throttling charging or sourcing energy from supplemental sources when demand exceeds grid capacity.
Bidirectional charging trends to watch for
Fleets as DERs. With the electrification of transportation, EVs, especially fleet EVs with centralized charging infrastructure, could become an important part of grid decarbonization. For instance, Amazon plans to have 100,000 electric delivery vehicles on the road by 2030, with a cumulative battery capacity of approximately 20 GWh. Because they operate on controlled and predictable schedules, fleets like school buses, car rentals, public transportation, and trucking companies can use bidirectional charging at scale in a way that grid operators can predictably plan for.
The interoperability of equipment and software will spur greater adoption of bidirectional charging. Last year, a private-public partnership announced a new interoperability framework that allows vehicles, chargers, and charging networks to communicate securely across the entire charging ecosystem. Pilot testing is set to begin sometime in 2025. Plug & Charge architecture lays the groundwork for V2G integration and is purpose-built to enable bidirectional energy transfer and other advanced grid services.
Developing business models to accelerate V2G adoption. Even if your local utility provider isn’t ready to handle the additional load of V2G charging, it soon will be. The V2G market will grow from over $14 million in 2024 to nearly $117 million by 2032, a 30 percent CAGR over the forecast period. Early adopters and first-movers are set to benefit the most from this rapidly emerging market.
Bidirectional charging can greatly accelerate renewable energy integration. V2G charging facilitates the integration of clean energy resources by accumulating, storing, and utilizing excess renewable energy. Renewable energy is usually at peak generation capacity during midday, when most EVs are parked. EV batteries store this excess energy and send it back to the grid during peak demand or when renewable energy generation is low. This integration enhances grid flexibility and reliability while offsetting fossil fuel peak generation.
Conclusion
Bidirectional charging, in all its forms, is poised to shift grid and transportation paradigms. By providing grid load demand services, resiliency, and renewable energy integration, bidirectional EV charging will be an important asset for grid operators and CPOs. By integrating smart energy management software, operators can optimize their processes to unleash the full potential of millions of batteries on wheels.
