Vehicle-to-grid (V2G) technology: Key challenges and developments

The global electric vehicle (EV) market has grown tremendously in the last decades. But are utility grids prepared to handle the additional electricity demands from EV charging? 

Vehicle-to-grid (V2G) is a charging technology that’s mutually beneficial for consumers and energy companies. It allows the one-way flow of energy from an electric car’s battery back to the power grid. This technology enables us to make the most of existing vehicles, as EVs essentially turn into big batteries on wheels that help the grid. This is especially important when energy in the grid is produced from volatile renewable energy sources like wind and solar. 

There will be 140-240 million electric vehicles by 2030, which means that we'll have at least 140 million tiny energy storages on wheels with an aggregated storage capacity of 7 TWh.

What are the possibilities, challenges, and developments with V2G? In this blog post, we’ll consider four key V2G topics, with insights from top energy experts. 

Standards and interoperability for V2G implementation

Interoperability is a prerequisite for the mainstreaming of EVs. When more vehicles become V2G compatible, EV owners must be able to use different charging stations even if they're only a customer of one service provider. 

A good V2G experience also requires a low-cost charging network without any extra costs for using this technology through fleet or home chargers. 

Anders Hove, Senior Research Fellow at the Oxford Institute of Energy Studies and Project Director for the Energy Transition project at GIZ, explains: “For V2G to work, it has to be something that can be implemented across a variety of platforms at low-cost. Smart charging and payment for charging or for injecting power into the grid has to be more uniform. This requires some sort of standard or interoperability requirement from the policy makers that are supporting the build out of charging infrastructures.”

Charging infrastructure requirements for V2G

To be used for V2G, our current charging infrastructure requires an upgrade.

There are two ways to provide vehicle-to-grid charging: 

1. DC: All power electronics are housed inside the charging units. 
2. AC: The charger bidirectionalities are handled inside the vehicle. 

When it first came out, AC was expected to make the infrastructure cheaper, with costs of the extra hardware absorbed by the automotive manufacturer. But due to global grid codes, you need to certify the charger whether the power metrics are in the car or at the charging station.

“Regardless of whether you are using DC-coupled or AC-coupled, with the current infrastructure, the charging devices themselves cannot be effectively retrofitted for V2G,” summarizes Juha Karpinnen, Director of Energy Services at Virta.

Decentralised batteries vs. central energy storage systems  

How do decentralised batteries, like the ones in EVs, compare to the central energy storage systems, like grid-scale batteries? Energy experts have different views on this.

Usama Irshad, Senior Zero Emission Transport Engineer at Evenergi, explains how he sees the difference: “The primary purpose of the centralised EV energy storage system is to support the grid, whereas for EVs, the main purpose is commuting. From the reliability point of view, the central energy storage system is more reliable than EV batteries because the EVs have some uncertainty factors at this stage.”

Akash Roshan, Solution Manager at gridX, adds: “Fleet EVs like public buses, delivery vans, and school buses are more reliable compared to private EVs, where owners might not know when they’ll be charging, where they’re going, and how many kilometers they’ll be doing.” 

Ultimately, decentralised batteries bring a lot of value as they solve more challenges.

”By solving the problems locally with decentralised batteries, you can mitigate the critical congestion and integrate the local assets. Especially in rural areas, you can serve both the local needs as well as the more regional needs of the power system,” explains Juha. 

If we don't use V2G for most electric vehicles, then the energy storage requirements and overall investment cost for the grid will be significantly larger. Since electric vehicle batteries require no additional investments in hardware, they are by far the most cost-efficient form of energy storage. 

“If we are able to get V2G online in the next few years, that can really help reduce the investment costs and a lot of the downstream regions of the grid,” says Anders. 

The role of EV owners in V2G applications 

For the V2G grid to be reliable and used as energy storage, we need a large number of EVs to be part of it. So, what is the consumer’s perspective on V2G and how could we encourage more EV owners to take part in V2G?

EV owners’ main concern with V2G comes from the perceived lack of control. Since energy markets are not that known to the average EV user, V2G is seen as a bit risky—EV owners know it’s good, but don’t fully understand how it works. 

Through our V2G services at Virta, we discovered that EV owners must:

• Have full control over deciding when the car should be charged
• Be able to define what is the absolute minimum state of charge that the car can be discharged to
• Be informed of the forecast of the charging profile
• Have the option to opt out

With the Virta mobile app, EV owners get peace of mind and know that nothing will impact the ability to use their vehicle. 

“For the customer experience, you have to make sure that the information in the customer interface is good and valuable. With V2G, we need to know what different options we have, what the prices are, and how we could shift our consumption to either a cleaner or a cheaper or both time period,” says Anders. 

Battery degradation is another concern with vehicle-to-everything (V2X). To mitigate this, agreements with automakers, charging point manufacturers, and charging point operators are needed. With such agreements, the automaker would extend the battery warranty of the vehicle to also include V2X as long as there's a mutual agreement between the charging point operator and the charging station manufacturer on how the vehicle charging profiles are adjusted.