V2G Technology: How electric vehicles are becoming mobile power plants

EVs aren't just loads on the grid. With bidirectional charging, they're distributed storage - capable of supporting your home, your building, and the grid itself. This isn't a future concept. The hardware exists, the standards are maturing, and the economics are starting to make sense.

Here's the full picture.

What is V2G (and V2H, and V2B)?

Let's get the acronyms out of the way.

V2G - Vehicle-to-Grid. Your EV sends energy back to the electrical grid. The grid operator (or an aggregator acting on its behalf) orchestrates when and how much power flows from your battery back through the meter.

V2H - Vehicle-to-Home. Your EV powers your house directly. Think of it as a Tesla Powerwall, except it's parked in your driveway and has 60–80 kWh of capacity instead of 13.5.

V2B - Vehicle-to-Building. Same concept, scaled up. A fleet of EVs connected to a commercial building can shave peak demand or provide backup during outages.

The common thread: your EV battery isn't idle when parked. And the average car is parked about 95% of the time. That's a lot of unused capacity sitting in driveways and parking garages.

Why this matters now

Three trends are colliding at exactly the right moment.

EV adoption is hitting critical mass. Globally, there are over 40 million EVs on the road. Each one carries a battery pack between 40 and 100+ kWh. Multiply that out and you're looking at terawatt-hours of distributed storage that already exists - it's just not being used bidirectionally yet.

Grids are under stress. Electrification of heating, transport, and industry is driving demand higher while aging infrastructure struggles to keep up. The duck curve isn't theoretical anymore - it's an operational headache for grid operators from California to Germany.

Renewables need flexibility. Solar produces at noon, wind blows unpredictably, and demand peaks in the evening. The mismatch between generation and consumption is the core problem of the energy transition. Stationary batteries help, but they're expensive and take years to deploy at scale. EVs are already deployed. They just need the right charger and the right software.

How it works technically

The basic flow is straightforward, but the devil is in the integration.

Bidirectional charger. A standard EV charger is AC-to-DC (grid to battery). A bidirectional charger adds DC-to-AC conversion, turning the EV into an inverter that can export power. These are commercially available now from manufacturers like Wallbox, Fermata, and SMA. Costs are coming down but still run 2–3x a standard Level 2 charger.

On-board vs. off-board inverter. Some vehicles (like the Hyundai Ioniq 5 with its V2L outlet) have onboard bidirectional capability. Others rely on the charger itself to handle the conversion. The industry is moving toward making this a standard vehicle feature, but we're not there yet.

Control software. This is where it gets interesting. The charger needs to know when to charge, when to discharge, and how much. That decision depends on electricity prices, grid signals, battery state-of-charge, the driver's departure time, and degradation constraints. This is an optimization problem, and it's the layer where companies like us at Pstryk and others in the dynamic tariff space operate.

Aggregator role. A single EV exporting 7 kW doesn't move the needle for a grid operator. But 10,000 EVs coordinated by an aggregator? That's 70 MW of flexible capacity - comparable to a peaker plant. The aggregator pools distributed resources, bids into energy markets, and dispatches the fleet in response to price signals or grid operator commands.

Communication protocols. ISO 15118 handles the vehicle-to-charger communication, including Plug & Charge authentication and bidirectional power transfer negotiation. OCPP (Open Charge Point Protocol) manages the charger-to-backend connection. For V2G at scale, these two standards need to work together seamlessly. We're getting closer, but interoperability testing is still an active effort.

Use cases

Peak shaving. The most immediate value. Discharge EVs during the evening peak (when electricity is expensive) and recharge overnight (when it's cheap). For a building or fleet, this can meaningfully reduce demand charges. For the grid, it flattens the load curve without building new peaker plants.

Frequency response. Batteries react in milliseconds. An aggregated EV fleet can provide primary frequency response - injecting or absorbing power to keep the grid at 50 Hz (or 60 Hz, depending on your continent). This is a high-value ancillary service, and EVs are technically well-suited for it.

Backup power. A 77 kWh EV battery can power an average European household for 2–3 days. During outages, V2H turns your car into a generator - a quiet, zero-emission generator. For markets like the US where grid reliability is declining in some regions, this alone is a compelling reason to go bidirectional.

Fleet optimization. Municipal bus fleets, delivery vans, and corporate car pools present the strongest near-term V2G business case. They have predictable schedules, centralized charging infrastructure, and enough vehicles to make aggregation worthwhile. A school bus fleet that sits idle from 9 AM to 2 PM is a perfect candidate for midday solar absorption and afternoon peak discharge.

Economics: what's in it for drivers and fleets?

Let's be honest about the numbers.

Potential earnings for individual drivers vary wildly by market. In countries with aggressive time-of-use tariffs or capacity markets, an EV owner could earn €200–€500/year from V2G participation. In markets with flat tariffs and no ancillary services access, the number might be close to zero. Tariff design is the enabler here - without dynamic pricing that reflects real-time grid conditions, the price signal for V2G doesn't exist.

Fleet economics are stronger. A fleet of 50 electric delivery vans with coordinated V2G can generate meaningful revenue from demand charge reduction, arbitrage, and ancillary services - potentially offsetting a significant portion of charging costs. The business case gets stronger as electricity price volatility increases, which it will as renewable penetration grows.

Battery degradation - the elephant in the room. Every cycle wears the battery. The question is how much. Recent research from institutions like TU Delft and NREL suggests that smart V2G cycling (shallow cycles, temperature management, SOC kept in the 20–80% range) adds modest incremental degradation - roughly 1–2% additional capacity loss per year compared to charge-only use. That's manageable, especially if V2G revenue covers it. But it's not zero, and any honest economics analysis needs to account for it.

The key insight: V2G doesn't need to make drivers rich. It needs to make the grid more flexible while not making drivers worse off. Even revenue-neutral V2G that provides backup power during outages can be a compelling value proposition.

Policy and standards landscape

Technology is ready. Policy is catching up.

Interconnection rules are the biggest barrier in most markets. Exporting power from an EV back through the meter requires utility approval, updated interconnection agreements, and often a bidirectional meter. In some jurisdictions, this process is straightforward. In others, it's a months-long bureaucratic exercise designed for rooftop solar, not vehicles.

ISO 15118-20 is the key standard. It defines bidirectional power transfer, including V2G, V2H, and V2B modes, with Plug & Charge support and fine-grained power scheduling. Adoption is underway but uneven - most vehicles and chargers on the market today still run ISO 15118-2, which doesn't support bidirectional flows.

OCPP 2.0.1 adds support for V2G transactions on the backend side, including energy export metering and settlement. If you're building charging infrastructure today, OCPP 2.0.1 is the minimum version to future-proof for V2G.

Market participation remains fragmented. In some markets (UK, Netherlands, parts of the US), aggregators can already bid EV flexibility into balancing and ancillary services markets. In others, the regulatory framework simply doesn't accommodate mobile, distributed assets. This is changing, but not fast enough.

Challenges and myths

"V2G will destroy my battery." Addressed above. Smart cycling adds modest wear. The real risk is uncontrolled, deep cycling - which no serious V2G implementation would do. Battery management is a software problem, and it's solvable.

"My car won't be charged when I need it." Every V2G system worth its name lets the driver set a minimum SOC and departure time. The car discharges only within those constraints. If you need 80% by 7 AM, the system guarantees it. The driver is always in control.

"There aren't enough bidirectional chargers." True today, but the market is growing. As OEMs build bidirectional capability into more vehicles, charger manufacturers are following. The chicken-and-egg problem is real but starting to crack.

"Cybersecurity is a risk." Fair point. A fleet of internet-connected, grid-tied batteries is a target. ISO 15118 includes TLS-based secure communication, and OCPP 2.0.1 adds security profiles. But the attack surface is real, and as V2G scales, cybersecurity needs to be a first-class engineering concern, not an afterthought.

What happens next

The trajectory is clear, even if the timeline is uncertain.

Phase 1 (now): Smart charging. Shift EV charging to off-peak hours using price signals and schedules. This is already happening at scale and provides real grid value without any hardware upgrades beyond a connected charger. Dynamic tariffs - the kind we build at Pstryk - are the foundation layer.

Phase 2 (near-term): V2H and V2B. Bidirectional chargers hit mainstream price points. Homeowners use EVs as backup power. Commercial buildings integrate fleet vehicles into their energy management systems. The value is local and tangible - lower bills, resilience, peak shaving.

Phase 3 (medium-term): V2G at scale. Aggregators coordinate millions of EVs as virtual power plants. EVs participate in wholesale and ancillary services markets. The grid sees them not as unpredictable loads but as flexible, dispatchable assets.

Phase 4 (long-term): EVs as core flexibility infrastructure. In a fully electrified, renewables-dominated grid, the storage capacity in the vehicle fleet could rival or exceed dedicated stationary storage. EVs become a structural part of how the grid balances supply and demand.

We're building the software layer for a world where every connected device on the grid - EV, heat pump, battery, smart plug — is a flexibility asset. V2G is one of the biggest pieces of that puzzle. The technology works. The standards are converging. The economics will follow as tariffs catch up with reality.

The question isn't whether EVs will become mobile power plants. It's how fast we can remove the barriers standing in the way.