How EVs Can Become the Grid's “Mobile Power Bank”: The V2G Technology Making It Possible

The EV in Your Driveway Is More Than a Car — It's a Power Plant on Wheels

Imagine this: you plug in your electric vehicle at night, charge it at off-peak rates, and the next morning — instead of just driving to work — your car sells electricity back to the grid during the peak demand hours, earning you money while you sleep. This isn't a futuristic fantasy. It's the promise of Vehicle-to-Grid (V2G) technology, and it's already being deployed in pilot projects across Asia, Europe, and North America.

The global V2G market was valued at approximately USD 5.75 billion in 2025 and is projected to reach USD 20.24 billion by 2031, growing at a CAGR of over 22%. With more than 12.9 million public EV charging stations projected worldwide by 2030, the infrastructure foundation for V2G is rapidly taking shape. The question is no longer whether EVs will become grid assets — it's how quickly the technology can be deployed at scale.

What Exactly Is V2G?

V2G, short for Vehicle-to-Grid, is a technology that enables bidirectional power flow between an electric vehicle's battery and the electrical grid. Unlike conventional charging, where electricity flows in only one direction — from grid to vehicle — V2G-capable chargers allow power to flow both ways. Your EV can charge when electricity is cheap and abundant, and discharge — selling power back — when the grid is stressed and prices are high.

Think of it this way: a standard charger is like a straw. Electricity goes in one direction only. A V2G charger is more like a smart water gate — it can open both ways, letting power flow in or out depending on what the grid needs and what your car has available.

The benefits flow in two directions:

For the grid: V2G acts as a giant stabilizer. During summer heat waves, when air conditioning drives demand to its peak, thousands of connected EVs can collectively discharge power to prevent brownouts and voltage instability. During the night, when demand drops, those same vehicles recharge using surplus renewable energy that would otherwise be curtailed.

For the EV owner: V2G creates a new revenue stream. Charge at night when rates are low, discharge during peak hours when grid prices are high — a simple arbitrage play that can generate meaningful income. In some markets, V2G fleet operators have reported revenue of USD 3,000–4,500 per vehicle per year when battery degradation costs are carefully managed. In Denmark, V2G users earned USD 38–76 per month from frequency-regulation contracts alone, rising to USD 152 for commercial fleets with optimized dispatch.

The "Battery Stress" Problem — and How V2G Solves It

The most common concern about V2G is battery degradation. Frequent charge-discharge cycles could accelerate wear, and indeed, research suggests that daily V2G cycling may impose 9–14% state-of-health loss over 10 years. This is why most EV manufacturers have historically excluded grid-discharge activity from battery warranties.

The solution lies in combining V2G chargers with stationary energy storage systems. Think of the storage system as a large "buffer pool." When multiple vehicles discharge simultaneously, the buffer absorbs voltage and frequency fluctuations, keeping the grid stable. More importantly, the storage system can shoulder the frequent, rapid cycling that would otherwise degrade vehicle batteries. The vehicle battery is effectively "liberated" — it only handles moderate, predictable cycling while the stationary storage handles the high-frequency grid services.

This hybrid architecture is already moving from concept to deployment. In Nanjing, China, a full-scenario V2G demonstration project has accumulated over 111,500 kWh of vehicle-to-grid backup discharge, with 11 official vehicles, one bus, and 14 residential charging stations participating in grid backup service for more than 280 consecutive days. The Shenzhen Guangming Hongqiao Park fast-charging demonstration station, the largest single-station V2G facility in China, achieved a maximum charge-discharge power of 4.21 MW across 61 vehicles simultaneously.

The Communication Backbone: How V2G Actually Works

For V2G to function reliably, the vehicle and the charging equipment must communicate seamlessly. The EV needs to tell the charger how much energy it can provide, what its current state of charge is, and when the owner plans to drive away. The charger needs to relay grid conditions, pricing signals, and safety parameters.

This is where ISO 15118, the international standard for vehicle-to-grid communication, comes into play. Specifically, ISO 15118-20 — the second-generation standard — is the critical enabler for V2G. It defines the communication messages and sequence requirements for bidirectional power transfer (BPT), supporting use cases from vehicle-to-grid to vehicle-to-home (V2H) and vehicle-to-building (V2B). It also supports Plug & Charge (PnC), allowing drivers to simply plug in and let the system handle authentication, billing, and energy scheduling automatically.

In the V2G architecture, there are two key communication controllers: 

• EVCC (Electric Vehicle Communication Controller): resides in the vehicle and manages the communication session with the charging station. 

• SECC (Supply Equipment Communication Controller): resides in the charging station and coordinates with the EVCC to negotiate charging parameters, monitor the power transfer process, and manage grid interaction.

These two controllers exchange V2G messages over Power Line Communication (PLC)—data transmitted over the same charging cable that carries power. The communication session follows a defined sequence: from SLAC (Signal Level Attenuation Characterization) and SDP (SECC Discovery Protocol) through to authorization, parameter negotiation, and finally, the charge/discharge sequence itself.

For charger manufacturers and solution providers, implementing ISO 15118-20 compliance is not optional—it's essential. The EU's Alternative Fuels Infrastructure Regulation (AFIR) will require ISO 15118-20 implementation for public AC charging points from January 1, 2027, extending to private charging points as well. This regulatory mandate is accelerating the demand for compliant communication modules across the charging infrastructure industry.

Bringing V2G to Life: The AP-SE-B Core Board

Building a V2G-capable charging station requires sophisticated communication hardware and software. This is where embedded solutions like the AP-SE-B Core Board from AUPINS come into play.

The AP-SE-B is a PLC communication core board specifically designed for IEC/SAE AC EV chargers. It integrates stable, reliable PLC communication functions with optional PWM generation, CP/PD/PP signal detection, and other SECC core functions — all in a compact module measuring just 50mm × 10mm × 30mm.

What makes the AP-SE-B particularly relevant for V2G deployment is its comprehensive protocol support. The board fully supports both ISO 15118-2 and ISO 15118-20 international standards, including:

• ISO 15118-20 EIM (External Identification Means) for flexible authentication

• ISO 15118-20 PnC (Plug & Charge) for seamless user experience

• ISO 15118-20 BPT (V2X) for bidirectional power transfer — the core enabler of V2G, V2H, and V2B applications

In practical terms, this means an AC charging station built around the AP-SE-B module can support V2H (Vehicle-to-Home) backup power, V2G (Vehicle-to-Grid) energy trading, coordinated charging for demand response, and Plug & Charge for automatic authentication—all through a single embedded solution.

The module communicates with the AC main control board via UART interfaces (two available) and a USB interface for configuration and diagnostics. It operates across a wide temperature range of -40°C to +85°C, making it suitable for both indoor and outdoor charging installations. Firmware upgrades are supported via OTA, and the board includes logging and log retrieval functions for integration troubleshooting and communication analysis.

For charger manufacturers, the value proposition is clear: the AP-SE-B reduces integration complexity, shortens development cycles, and helps bring next-generation V2G-capable charging products to market faster. Rather than building PLC communication and ISO 15118 protocol stacks from scratch, manufacturers can integrate a pre-certified, pre-tested module and focus their engineering resources on the higher-level features that differentiate their products.