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Charging Technology

What is the difference between V1G and V2G


Joachim Lohse

July 22, 2022

This article is a summary of Joachim Lohse, Ampcontrol’s CEO, speaking at the panel “The Economic Value Propositions to Make the Business Case for Bi-Directional Charging.” Here he explains the difference between V1G and V2G, their benefits, and how to apply them to your electric vehicle charging operations.

Date: July 21, 2022
Speaker: Joachim Lohse
Webinar: The Economic Value Propositions to Make the Business Case for Bi-Directional Charging
Hosted by: NC Clean Energy Technology Center & NAFA

Before going into V2G (vehicle-to-grid), I want to go into problems that extra fleet operators might have quickly, and the three most important ones are:

  1. High power demand of vehicles: If you have a depot with buses, trucks, and passenger vehicles, you will get high power demand. So usually, what we see, fleets typically start with 4 or 5 vehicles in one location. Power demands and energy costs become critical for operations once 20-30 vehicles are in the location.
  2. Time of Use rates: This does not depend on your power demand but at what time you're charging. Maybe your energy costs are much higher during the day than at night.
  3. High downtime of chargers: Chargers have hardware and communication errors that need to be dealt with quickly.

Before talking about the V2G approach, I wanted to talk about the V1 G approach.

Why is V1G important to understand V2G?

V1G or smart charging for electric vehicles

I would say V1G is the first version of smart charging. 
Smart charging can be many things, but V1G is the beginning of how you want to manage your vehicle's power. 
If you usually plugin all vehicles simultaneously, you will have a high power demand. This type of charging is uncontrolled; everyone will get the same power level, and there's nothing intelligent about it. 

Now, V1G, or smart charging, allows you to shift power and control specific chargers depending on their use.

Above, you see an example of one vehicle that arrives at 6 PM and has to leave at 7 AM, meaning the vehicle will be charging overnight and doesn't need to leave immediately. Typically, smart charging algorithms will identify a variety of things, such as:

  • When the vehicle has to leave.
  • When I can charge.
  • When my energy is cheap.
  • How I can reduce total power demand.

This is not V2G yet, but it's the first approach to how you can optimize the charging of electric vehicles.

Why is V1G already an excellent first approach? 

benefits of smart charging for electric vehicle fleets

First of all, it helps you to identify errors. Looking at accumulated data will help you to:

  • Identify errors
  • Send an alert if a vehicle is not charging.
  • Send an alert if there is a broken charger plug. 
  • Send an alert if there's a power loss and you have no available energy for charging. 

Also, you can already start saving costs by reducing your peak demand. 

Above, you see an example of one of our customers, Revel, an electric taxi fleet in New York. They have 25 DC fast chargers that have a lot of power usage. They have more than 200 vehicles already operating on the site, so there is very high utilization.

Here they save costs by intelligently reducing the power demand while ensuring the vehicle's on-time departure. 

What is V2G and how to use it?

V2G or vehicle-to-grid for electric vehicles

What you see above is a similar graphic from before, but in this case, the vehicle is discharging. First, the vehicle arrives at the depot at 4 PM and starts charging. At 6 PM, the utility sends a V2G event due to high stress on the grid. The vehicle then discharges its battery into the grid to help alleviate the stress. 

This situation can happen for several reasons, such as the high use of air conditioners due to higher-than-normal temperatures. The utility might not have predicted this, so they trigger an emergency V2G call.

Another situation for V2G events triggers is "predicted response" or V2G programs. In this case, the utility predicts high grid stress, and they send a V2G signal to the vehicle owners ahead of time so that they can prepare for it.

Usually, you don't decide: "I'm going to start discharging my vehicle because I want to." Utilities drive 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. 

If the V2G event is sent by the utility the day before, a smart charging software can plan this event for tomorrow, for example, and then arrange to discharge a vehicle at the set time. You cannot just do this randomly. The system has to know that a vehicle will be plugged into a charger at the stated time, and it has to know how much power the vehicle could provide to the grid while maintaining your operations going without interruptions.

As a fleet operator, your primary goal will always be to provide your business service reliably and efficiently. Having your vehicles charged on time for their next shift will come above any V2G signal the utility might send. You must choose to enroll in a utility V2G program that allows you to maintain your operations intact.

What are the benefits of V2G?

V2G for electric vehicle fleets

V2G Utility Program

The most significant benefit of V2G for a fleet operator is to generate extra revenue.
As we mentioned before, V1G, or smart charging, will help you to monitor chargers, reduce power demands, and reduce the total costs. In comparison, V2G can do all of this and also generate additional revenue. Your total cost of ownership is lower because you are generating revenue through V2G utility programs.

By enrolling in a V2G program, the utility will pay you to discharge your vehicle's battery. This means you will get monthly cash flow by being part of this program. Let's say you enroll, and the utility triggers only 1 or 2 events in a month because the grid is pretty stable all the other times. You still get paid the full amount because you were available to execute the other signal.

In other cases, you only get paid if you execute the event. It all depends on the program you enroll in and where your site is located.

Vehicle as Energy Storage

You can use the vehicle as energy storage/ local storage on your site. This might be interesting if you have very critical building operations but not necessarily important vehicle operations. Maybe you have a bakery or a manufacturing plant where you need reserved power to ensure your business operations fully. In this case, you can potentially use the vehicles for energy storage for a short time. This wouldn't work for two days, but maybe for a few hours.

For example, right now, 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 operate the business uninterrupted during the blackout. The building can use the vehicle's power for the next couple of hours or for as long as the outage lasts. When the power is back, you can start charging vehicles again, so they are ready for their next shift on time. All this has to be calculated in real-time.

Benefits of vehicle-to-grid (V2G) for electric cars

Listen to the full webinar here.

Read more about V2G on: What are OCPP, IEC 63110 & ISO 15118 and How Do They Relate to V2G?

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