Companies that electrify their fleets calculate the return on investment in terms of avoided fuel costs, reduced maintenance and eventual image advantage. This calculation is correct but incomplete. The electric fleet parked in the yard during hours of peak electrical demand is, simultaneously, a set of batteries with discharge capacity that can inject energy back into the grid or the building — reducing the company's demand at the time of greatest cost or even selling energy to the distributor. The vehicle-to-grid, or V2G, concept transforms the cost of purchasing electric vehicles into investment in energy infrastructure.
How V2G works technically
The principle is simple: electric vehicles have batteries that can charge (receive energy) or discharge (supply energy). Unidirectional chargers — the most common — only allow charging. Bidirectional chargers allow for both streams. V2G is the application of this bidirectional flow connected to the public electrical grid or building power system.
When applied to the public grid (V2G itself), the vehicle can sell energy back to the distributor during peaks in demand, when the energy is worth more. When applied to the building's own system (vehicle-to-building, or V2B), the vehicle unloads to cover the building's demand at the highest cost, reducing contracted demand or peak charges. Vehicle-to-home (V2H) applies the same concept on a residential scale.
The necessary components are: vehicles compatible with bidirectional discharge — the Nissan Leaf pioneered the CHAdeMO standard, the Hyundai Ioniq 5 and Kia EV6 support V2G, and most manufacturers have models with this capability released or announced for 2025-2026 — certified bidirectional chargers, energy management system (EMS) that decides when to charge and when to discharge based on rates and demand, and, in the case of V2G to the grid, agreement with the local distributor for reverse energy flow.
The operational requirements that determine viability
The first variable that defines whether V2G makes sense for a fleet is the vehicle usage pattern. V2G only works with parked and connected vehicles during the period of energy interest — generally peak hours, between 6 pm and 9 pm in Brazil. A fleet of delivery vehicles that work from 7am to 6pm and park in the connected yard after 6pm is a perfect candidate. A fleet of executives that can be activated at any time does not have the same profile.
The second variable is the battery capacity available for discharge. Discharging an electric vehicle battery every day for energy use accelerated the degradation of that battery — it was the main concern that delayed the commercial adoption of V2G. The most recent field data, especially from pilot projects in Europe and Japan, shows that degradation with V2G cycles managed by an EMS system is lower than expected and within limits accepted by manufacturers who guarantee V2G in their models. The key is intelligent management: the system should never deplete the battery below the operational minimum and should prioritize leaving the vehicle charged for the next day's use.
The third variable is the location’s electrical infrastructure. Bidirectional chargers of relevant power require three-phase connections with adequate capacity, and integration with the building's energy system requires inverters and control systems that represent additional investment in addition to the chargers.
What the economy might look like
The numbers for a V2G project fundamentally depend on the local tariff structure. In Brazil, the main financial driver is not V2G to the grid (which still has regulatory limitations) but V2B — using the fleet's batteries to reduce the building's peak demand.
The demand contracted in energy contracts for group A consumers (medium voltage) is charged regardless of actual consumption — you pay for availability. Exceeding the contracted limit generates extra high charges. Managing demand to keep the peak below the contracted limit is a direct way to reduce costs. A fleet of 20 vehicles with 60 kWh batteries each represents 1.2 MWh of storage capacity — enough to make a real difference in demand management at industrial facilities and medium-sized distribution centers.
In markets with time-of-use tariffs, the financial model adds price arbitrage: loading in the early hours of the morning at the lowest rate and unloading in the afternoon peak at the highest rate. The Brazilian tariff spread between peak and off-peak hours in group A contracts can be in the order of 3 to 5 times, which makes arbitration economically relevant.
The Brazilian regulatory scenario
Brazilian electricity regulation was, until recently, structured for unidirectional flow. ANEEL's Normative Resolution 482/2012, which created the framework for distributed micro and minigeneration, opened space for the injection of energy into the grid from sources such as solar photovoltaics, but the application to electric vehicles in V2G was in a gray area.
The 2022 regulatory update with the Legal Framework for Distributed Micro and Minigeneration (Law 14,300/2022) brought more clarity to distributed generation in general, but the specific V2G regulation is under development at ANEEL. Pilot projects with distributors such as CPFL, Enel and Energisa are already testing operational and compensation models, and the definitive regulatory framework should be consolidated over the next two years.
For companies planning electric fleets now, the safest strategy is to install bidirectional infrastructure early on — the marginal cost of opting for bidirectional versus unidirectional chargers is lower than retrofitting later — and monitoring regulatory progress to enable V2G for the grid once the rules are defined. V2B is not dependent on regulatory approval and can be implemented today.
How to assess the potential for your fleet
The starting point is a mapping of three variables: size and total battery capacity of the future or current fleet, vehicle usage hours and how long they are parked and connected, and the structure of the location's energy bill — especially if there is a demand contract and what is the spread between peak and off-peak times.
With this data, it is possible to model the potential for contracted demand reduction and rate arbitrage, and compare the incremental investment in bidirectional chargers and EMS system with the expected return. European projects with fleets of 10 to 50 vehicles have reported a return on incremental investment in V2G of between three and six years, with chargers having an estimated useful life of fifteen years. This spread makes the project attractive for companies with a long-term planning horizon — which are exactly the ones that should be electrifying corporate fleets now.
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