Bidirectional Charging of EVs: The Future of Energy

Electric vehicles (EVs) are transforming not only how we travel, but also how we interact with energy. Thanks to bidirectional charging, an EV can do more than just charge: it can also deliver power back to your home, devices, or even the electricity grid.

At BlueBird Power, we believe bidirectional charging plays a key role in the transition to a sustainable energy system. In this article, we explain the difference between AC and DC bidirectional charging, what V2L, V2H, and V2G mean, the role of the ISO 15118-20 protocol, and how we envision EVs as “batteries on wheels.”

What is Bidirectional Charging?

With traditional charging, electricity flows only one way: from the grid to the battery. With bidirectional charging, power can flow both ways. This unlocks new applications. EVs shift from being pure consumers of energy to becoming active energy storage and optimization units—making the system more flexible, sustainable, and resilient.

AC vs. DC Bidirectional Charging

A key distinction in charging technology is whether charging happens via alternating current (AC) or direct current (DC).

• DC bidirectional charging
  With DC charging, the inverter is built into the charging station. It converts the EV battery’s direct current into alternating current for your home or the grid. This provides a lot of control but makes the charger larger and more expensive.

• AC bidirectional charging
  With AC charging, the inverter sits inside the car. This makes the charging station simpler and cheaper since it doesn’t need an inverter. However, the vehicle itself must support bidirectional charging. For consumers, AC chargers are usually more affordable, making them attractive for home use and V2H applications.

V2L, V2H and V2G Explained

Bidirectional charging enables three main applications:

• Vehicle-to-Load (V2L): Use your EV as a mobile power source for devices. Useful for camping, DIY projects, or emergencies.

• Vehicle-to-Home (V2H): Your EV powers your home. This can be during an outage, or to make smarter use of self-generated solar energy—for example, charging your car with solar power during the day, then discharging it at night to run your lights or oven.

• Vehicle-to-Grid (V2G): The most advanced application. EVs return power to the grid, helping balance supply and demand. This can apply to several markets, such as the day-ahead market, frequency balancing, or congestion management.

At BlueBird Power, we see V2G as the future: millions of EVs working together as a distributed virtual power plant.

Customer Benefits of Smart and Bidirectional Charging

Bidirectional charging isn’t only about sustainability—it’s also about saving money.

With smart (unidirectional) charging combined with a dynamic energy tariff, consumers already save an average of €250 to €400 per year compared to a fixed tariff. With bidirectional charging, these savings can easily double, reaching up to €800 annually.

By using your EV battery to avoid expensive peak hours—or even selling power back to the grid—energy costs drop significantly, and the payback period of your charging station shortens.

ISO 15118-20: The Communication Standard

For seamless interaction between vehicles and chargers, a universal language is required. That’s the role of the ISO 15118-20 protocol.

This protocol defines how EVs and chargers exchange information about charging, billing, and bidirectional energy management. It’s comprehensive—and therefore complex—so it will take time before it’s fully implemented. Some manufacturers use proprietary protocols to get started faster, but these limit interoperability.

The true value of bidirectional charging only emerges once a standard like ISO 15118-20 enables full compatibility across systems.

BlueBird Power: Ready for the Future

Our chargers are already fully prepared in terms of hardware for bidirectional charging. The advanced electronics support applications like V2H and V2G. The challenge lies in the software.

Since ISO 15118-20 is still being finalized, we ensure our chargers remain future-proof with over-the-air (OTA) updates. Once the standard is complete and automakers provide support, our chargers will be immediately ready for bidirectional charging.

Our Vision: Batteries on Wheels

At BlueBird Power, we see EVs as an essential part of the future energy system. Imagine this:

• EVs charge when there’s a surplus of solar and wind energy.

• EVs feed power back during peak hours, making fossil energy largely unnecessary.

• EVs provide backup power during outages, increasing household resilience.

This is our vision of “batteries on wheels”—where mobility and energy converge in a smart, renewable future.

Conclusion

Bidirectional charging is more than just technology—it’s a new way of managing energy. Whether V2L, V2H, or V2G, the possibilities are vast.

The future requires collaboration between automakers, charger manufacturers, and standards such as ISO 15118-20. At BlueBird Power, we are ready—with robust hardware, flexible software, and a clear vision.

The future is not just about charging your car, but about managing your energy smartly.