What exactly is V2G, and why is bidirectional charging a game-changer for the future of energy?
In this article, we take a closer look at the technology and what it means for both EV owners and the energy grid.

What is ISO 15118?

ISO 15118 is a global communication standard that lets your electric car and charging station "talk" to each other through the charging cable. 

Why it matters:

• Enables Plug & Charge (just plug in and charging starts automatically).
• Supports real-time info sharing between your car and charger, such as battery level and how much energy is needed.
• Lays the foundation for future technology like Vehicle-to-Grid (V2G) communication. 

To support ISO 15118, both the vehicle and the charger must have built-in hardware (this isn't something that can be added later through a software update).

Zaptec Pro and Zaptec Go 2 chargers have built-in ISO 15118 hardware, making them future-proof for evolving smart charging solutions.
Zaptec Go does not currently support ISO 15118.

What is Plug & Charge?

Plug & Charge is one of the most user-friendly features enabled by ISO 15118. Simply connect your EV, and charging starts automatically, with no need for apps, RFID cards, or extra steps.

How it works:

1. Plug in your EV.

2. A secure digital connection happens between the car and the charger. 

3. The system automatically recognises your vehicle's identity.

4. Charging starts automatically. 

The process is safe and secure, using encryption to protect your data and prevent unauthorised access.

Not all EVs or chargers support Plug & Charge just yet, but more are on the way. Zaptec Go 2 and Zaptec Pro already include the hardware to support this feature in the future.

What’s the difference between V2G, V2H, V2L and V2X?

These terms are often used together, but they refer to different uses for bidirectional power: 

What is V2G (Vehicle-to-Grid)? 

Vehicle-to-Grid (V2G) refers to the technology that allows electric vehicles to send energy back to the power grid. In other words, EVs, which traditionally only receive electricity, can also return power to the grid when needed. This is particularly useful during times of high electricity demand or when there is a shortage of renewable energy sources like solar or wind power.

Why is bidirectional charging important?
Bidirectional charging allows EVs to become active players in the energy system. With millions of EVs on the road, each vehicle could contribute to grid stability, reduce the need for fossil fuel power plants, and even help owners save or earn money by participating in flexible energy schemes.

What needs to be in place for V2G to actually work?

1. The vehicle (EV)
   • The electric vehicle must be equipped with a bidirectional onboard charger. Most EVs today do not yet support this feature, but many manufacturers are actively experimenting with this now.
     
     
2. The charging station
   • To support V2G functionality, the charger must be equipped with ISO 15118 hardware and firmware, include a bidirectional energy measurement, and have safety mechanisms for exporting energy power back to the grid.
   • Currently, only the Zaptec Go 2 includes a bidirectional calibrated energy meter (MID). The Zaptec Pro supports ISO 15118 but does not yet include bidirectional metering for energy export (though this may become possible through future updates).
     
3. The installation (Grid protection)
   • In many countries, sending electricity back to the grid requires additional safety measures to ensure grid stability. This usually includes a dedicated grid protection unit.
   • For the Zaptec Go 2, this means a separate protection unit must be installed inside the fuse box. At this time, neither Zaptec Go 2 nor Zaptec Pro include built-in grid protection, although Zaptec continues to evaluate new requirements as standards evolve.
     
     
4. The ecosystem (Energy providers and software)
   • Even with compatible vehicles and hardware, V2G also relies on energy providers, grid operators, charging platforms, and Charge point operators (CPOs). This is still being developed. However, once fully established, it will enable V2G to optimise energy distribution, support the grid during demand, and play a vital role in the transition to more sustainable energy systems.
     
     

What is SoC (State of Charge) and why does it matter?

State of Charge (SoC) is simply a term used to describe how full your EV battery is. 

With ISO 15118, your EV can tell the charger:

• How much energy it currently has.
• How much energy it needs. 
• When it needs it. 

This enables more efficient charging, which is especially useful if you’re using solar panels or charging during off-peak hours.

Currently, only a few vehicles support SoC-based smart charging, but this is expected to grow. Zaptec is exploring how to integrate this functionality as the market evolves.

Is my Zaptec charger ready?

• Zaptec Go 2: Includes ISO 15118 hardware and is ready for future features like Plug & Charge and V2G (with additional setup).
• Zaptec Pro: ISO 15118 hardware included, but doesn’t currently support bidirectional metering for energy export (V2G).
• Zaptec Go: Does not support ISO 15118.

What’s next for smart charging?

The EV world is moving fast and Zaptec is ready to support what's next. As more EVs and homes adopt smart charging features, and as governments define new standards, we’ll continue to update our tech to support:

• More Plug & Charge-ready EVs and chargers.
• Smarter energy usage, integrated with home and solar setups.
• Backup power functionality from your vehicle.
• Full support for Vehicle-to-Grid as standards and infrastructure mature.

Looking for documentation or technical specs?

Click here to access documentation for Zaptec chargers.

Updated 25 March 2025 10:39