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Charging Technology

How to use V2G with your Electric Vehicle Fleet


January 17, 2023

V1G has been replaced by V2G. For fleet operators, it’s important to understand both technologies and the difference between them.

Fleet operators routinely face a range of issues when it comes to moving from V1G (standard smart charging from grid to vehicle only) to V2G (vehicle-to-grid which is bidirectional smart charging).

Chief among the challenges of transitioning to V2G are:

  • high power demand – even just four or five vehicles in one location significantly increases energy costs and will grow as operations expand to say 20-30 EVs at once.
  • time of use rates – variable electricity tariffs dependent on peak hour usage.
  • potential bottlenecks – charger downtime over extended periods if hardware and communications issues are left unresolved.

In this article, we’ll explain what V1G and V2G smart charging are and how you can overcome the challenges of moving to V2G.

How Does V1G Smart Charging Work?

V1G is the first iteration of smart charging. It allows you to manage your vehicle’s power more effectively. 

Without V1G, if you plug in all of your EVs simultaneously, it puts a big power demand on the grid. In other words, the charging is uncontrolled. Every vehicle gets the same power level and there is no intelligent distribution of the power between different chargers.

V1G changes uncontrolled charging into smart charging. It enables fleet operators to shift power between different chargers depending on their requirements. 


Let’s take a look at an example scenario.

V2G use case Ampcontrol

The example above shows a vehicle that arrives at the depot at 6 pm and must leave by 7 am the following morning. The EV can be charged overnight and doesn’t need to be charged right away for immediate departure. 

The V1G smart charging algorithms will identify a number of things, including:

  • The departure time
  • How long it will take to charge the EV 
  • Price of energy during different time periods, based on the tariff
  • How to reduce the overall power demand.

It is a step in the right direction from uncontrolled charging, but it is not as powerful as V2G, as you’ll see in a moment.

Advantages of Using V2G Over Uncontrolled Charging

  • Highlights inefficiencies or errors in charging schedules
  • Sends an alert if a vehicle fails to charge
  • Identifies broken charger plugs and sends an alert
  • Alerts you to power loss and consequent charging failure
  • Helps to cut costs by reducing peak demand.

Advantages of Using V2G for EV charging

The picture above shows the benefits of applying Ampcontrol to deliver V1G smart charging for one of our customers, Revel, an electric taxi fleet in New York. 

One of Ampcontrol’s customers, Reve,l operates 25 DC fast-chargers that require a lot of power. More than 200 vehicles operate from the site, so there is very high utilization. Ampcontrol helped them to reduce costs by intelligently decreasing the power demand while ensuring the on-time departure of every vehicle.

How Does V2G Smart Charging Work?

The best way to explain V2G smart charging is by referring to an example.

V2G case study with Ampcontrol

The scenario above is similar to the one in the previous section, but this time the vehicle has a session of discharging in-between charging sessions. First, the vehicle arrives at the depot at 4 pm and starts charging. At 6 pm, the utility company activates a V2G event due to high stress on the grid by sending a signal to the charger. Between 6 pm and 8 pm, the vehicle discharges its battery into the electricity grid to help alleviate the stress.

High grid stress can occur for a number of reasons, such as high usage of air conditioners due to above-average temperatures. The utility may not have predicted this, so they trigger an emergency V2G event.

Another possible situation that triggers a V2G event is a "predicted response" or a V2G program. In this case, the utility predicts high grid stress, so they send a V2G signal to the vehicle owners ahead of time, allowing them to prepare for it.

Utilities will often schedule these events to help them manage the grid stress by discharging your vehicle's battery at a specific time of the day. In other words, you provide power to the grid instead of taking power from it.

Utility V2G programs generate additional revenue for fleets, as they pay for the energy sent back to the grid.

Managing V2G Events Using Smart Charging Software

If the V2G event is sent by the utility the day before, a smart charging software solution (such as Ampcontrol) can plan the event in advance and arrange to discharge a vehicle at the set time.

In order to do this, the system must know that a vehicle will be plugged into a charger at the stated time. It also needs to know how much power the vehicle can provide to the grid while still maintaining your charging operations going without disruption.

V2G Program Considerations & Benefits

As a fleet operator, your primary goal is to provide charge EVs reliably and efficiently. 

Making sure that your vehicles are charged on time and ready for their next shift is a higher priority than any V2G signal the utility might send. Therefore, fleet operators must be careful to choose a utility V2G program that allows you to maintain control over your charging operations.

Additionally, the payment structure for V2G varies depending on the terms and conditions of the program. Some programs will pay you a monthly set amount for a scheduled number of V2G events, whether those events are executed or not. Other programs will only pay for each event that is executed. The type of payment conditions depend on the location of your site and the type of V2G program you enroll in.

The main advantages of V2G smart charging are:

  • Generates additional revenue
  • Reduce total cost of ownership (TCO)
  • Helps to keep the utility grid operational
  • Enables you to use your vehicles as energy storage for your site.

Using V2G As On-Site Energy Storage

V2G smart charging allows you to use EVs for on-site energy storage. This can be an advantage if you have very critical building operations that take priority over your vehicle operations.

For instance, a manufacturing plant that depends on reserve power to ensure full uninterrupted operation may benefit from V2G. In this case, the plant owner may be able to use the energy stored in EVs for a short period if there is a power outage, in a similar way to on-site generators. It may provide power for two to three hours or more, depending on the number of fleet vehicles and charging stations.


Here at Ampcontrol, we have a customer in South Africa who has, on average, one power outage per day that can take several hours. In this case, the vehicles can help the business to remain operational during the blackout. 

Ampcontrol enables the building to draw power from EVs for as long as the outage lasts. When the power returns, the vehicles automatically start charging again, so they are ready for their next shift on time. 

To find out how Ampcontrol can help you to implement V2G charging, book a demo today. 

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