Vehicle-to-Grid (V2G)

Vehicle-to-Grid (V2G) is a bidirectional energy system that allows electric vehicles (EVs) to both draw electricity from the grid and export electricity back to it. Instead of acting only as electrical loads, EV batteries function as mobile energy storage assets, supporting grid stability, reducing peak demand, and increasing renewable energy utilization—particularly solar PV.

In modern solar designing and distributed energy systems, V2G plays a key role in grid flexibility, peak load management, and renewable integration. For residential, commercial, and microgrid projects, V2G allows EVs to store excess solar generation and discharge it during high-demand or high-tariff periods, improving overall system efficiency and resilience.

Key Takeaways

V2G enables EVs to function as mobile energy storage
Improves grid stability and peak demand management
Enhances solar self-consumption and cost savings
Requires bidirectional chargers and intelligent controls
Plays a critical role in future solar-plus-storage systems

What It Is

Vehicle-to-Grid is a technology framework that enables two-way power flow between an electric vehicle and the electrical grid using bidirectional chargers, inverters, and intelligent control software.

In a traditional EV setup, electricity flows in one direction—from the grid to the vehicle. With V2G, energy can flow from the vehicle back to the grid, a building, or a home, depending on system configuration and control logic.

For professionals working with Solar Layout Optimization, Solar Load Analysis, and Solar Proposals, V2G expands the system boundary. EVs become part of the broader energy management system, influencing load curves, storage sizing, and long-term ROI modeling.

How It Works

V2G systems operate through coordinated interaction between hardware, software, and grid communication protocols.

Step-by-Step Operation

Bidirectional Charging Infrastructure: A V2G-enabled charger allows electricity to flow into and out of the EV battery, similar to a stationary Battery Energy Storage System (BESS).‍

Energy Monitoring & Control Control platforms track grid conditions, electricity prices, solar generation, and EV availability—often integrated into an Energy Management System (EMS).

Charging Mode (Grid / Solar → Vehicle)

EVs charge during off-peak hours or when rooftop solar generation is high.
Excess solar energy that would otherwise be exported or curtailed can be stored in the EV battery.

Discharging Mode (Vehicle → Grid / Building)

During peak demand or high tariffs, stored energy is discharged.
Power may support the grid, a commercial facility, or residential loads.

Settlement & Compensation: Utilities or grid operators compensate EV owners for exported energy or grid services such as demand response.

When paired with accurate Shadow Analysis and generation modeling, V2G dispatch can be precisely aligned with solar production profiles and peak demand windows.

Types / Variants

1. V2G (Vehicle-to-Grid)

Energy is exported directly to the utility grid for peak shaving, frequency regulation, or grid balancing.

2. V2H (Vehicle-to-Home)

The EV supplies electricity to a home, often integrated with rooftop solar and backup strategies under solar + storage systems.

3. V2B (Vehicle-to-Building)

Commercial EV fleets supply power to buildings, reducing peak demand charges and improving energy cost control.

4. V2X (Vehicle-to-Everything)

An umbrella term covering all bidirectional energy interactions, including microgrids and emergency power support.

5. How It’s Measured

V2G performance is evaluated using energy, power, and grid-service metrics:

Bidirectional Power Capacity (kW) – maximum charge and discharge rate
Energy Capacity (kWh) – usable battery energy available for export
Round-Trip Efficiency (%) – energy retained after charge–discharge cycles
Response Time (seconds) – speed of reaction to grid signals
Battery Degradation Impact (%/year) – additional wear due to V2G cycling

These parameters directly affect system modeling in tools such as the Battery Size Calculator and Solar ROI Calculator.

Practical Guidance (Actionable Steps)

For Solar Designers

Treat EV batteries as flexible storage assets, not fixed loads.
Align V2G dispatch with solar peaks using Solar Layout Optimization.
Evaluate export limits, interconnection rules, and inverter constraints early.

For Installers

Ensure compatibility between EVs, bidirectional chargers, and site electrical infrastructure.
Validate grounding, protection devices, and communication reliability during installation.

For EPCs & Developers

Use V2G to reduce reliance on stationary batteries in fleet and commercial projects.
Combine V2G with demand response programs to improve project economics.
Include V2G assumptions in Solar Proposals and long-term performance forecasts.

For Sales & Business Teams

Position V2G as a future-ready energy strategy that enhances resilience and ROI.
Quantify value using the Solar ROI Calculator and Battery Size Calculator.

Real-World Examples

Residential Example

A solar-powered home charges an EV during midday excess generation. In the evening, the vehicle supplies power back to the home, reducing grid imports and improving self-consumption.

Commercial Example

A logistics warehouse uses an EV fleet with V2B capability to offset peak demand charges. Vehicles discharge during high-tariff hours and recharge overnight or during solar peaks.

Utility / Grid Example

A utility aggregates thousands of EVs for grid services. The distributed V2G network stabilizes frequency during periods of high renewable penetration.