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Ultimate Guide To Implementing EV Smart Charging In OCPP Applications


November 11, 2021

Looking for a comprehensive guide to electric vehicle smart charging for charging point operators? You’ve come to the right place!

Let’s dive in and take a detailed look at EV smart charging, how it works, the benefits, and how you can apply it to your charging point operations.

After reading this article, be sure to check out our report What Is OCPP and How to Use It For Smart Charging to discover how you can optimize your charging operations.

If you want to learn more about energy management and smart charging, download our new report, "Energy Management 101: How to Efficiently Charge Electric Fleets".

What is smart charging for electric vehicles?

The best way to describe smart charging is to start with normal charging.

Normal charging involves EV drivers plugging their vehicle into any random charge point. The charge point provides maximum charging power until the EV battery reaches 100% SoC, and then it automatically stops the charging process.

Smart charging, on the other hand, means that the charging process is directly coordinated and automatically managed by a central system. Instead of charging all vehicles at the maximum capacity of the charge point, the central system takes over control and applies intelligent decision-making. This means that the power output of the charging station is reduced, increased, delayed, or a combination of all three.

charging prioritization with smart charging example
Smart Charging Example

Also, smart charging means that the EV driver is advised on which charging station they should select, based on their departure time or the required energy for a trip. This might seem like a less obvious benefit, but it will be more and more important when companies start mixing slow and fast chargers at locations.

Last but not least, smart charging for EVs also means that we can connect charging stations with power plants and energy storage. The output looks similar to a microgrid. This means that you can increase the total power availability at locations or provide less, depending on the public utility.

We’ll expand on this use case in more detail later on in this article. But first...

How can you implement smart charging for electric vehicles?

We’ll dive into the technology stack in a little bit.

But first, let’s explore how you can provide smart charging and what it involves.

Smart charging can be simple or extremely complex and sophisticated. In the long run, most applications will require a sophisticated approach. The main reason for this is that drivers expect a fast and smooth process. In other words — charge fast when necessary or slow and cheap if possible.

We’re also getting closer to fully connected vehicles that communicate with either the charge point or cloud solutions.

When your company has built its own central charging system or even mobile apps, it doesn’t mean you can simply add a smart charging system. Smart EV charging relies on real-time control software that uses advanced algorithms. It differs entirely from the UX or UI-driven applications and IoT systems connecting to charging hardware.

For these reasons, here at Ampcontrol, we’ve specialized in developing advanced smart charging solutions for charging point operators (CPO) or fleet operators. These applications can easily connect to existing systems while you stay in full control of how the smart charging system coordinates your charge points or electric vehicles.

Use cases: smart charging for charging point operator

Let’s look at some of the common scenarios for EV smart charging.

Overall we can narrow it down to 4 use cases for charging point operators. However, please be aware that there are many more for electric fleet charging, utilities, or microgrid applications.

A) Demand Charges: Reduce the total power demand at locations with load management

Demand charge example

Demand charges are fees that energy companies bill to customers for electricity supply. These fees can easily be 50% of the total electric bill and are significant when charging electric vehicles.

The basic formula for demand charges uses the total power demand (Kilowatt = kW) during one month and a fixed rate per kW.

kW of demand * $/kW = $ Monthly Demand Charge

For example:

400 kW *  $12 =  $4,800

As a charging point operator, you can reduce the total power demand (kW) while delivering the same amount of energy (Kilowatt Hours = kWh). For instance, if a vehicle plans to charge overnight or during a long workday, the vehicle is connected to the charging station for more than 8 hours. Therefore, there is no need to charge the vehicle rapidly in, say, 2 hours.

Reducing the total power demand is often the first and most important step when applying smart charging for EV charging networks.

B) TOU Rates: Focus your EV charging at times when energy costs are cheaper

TOU rates for ev charging

The good old times of analog energy meters are gone. In many countries, we had a simple energy meter that totals up the energy usage (kWh) over the course of one year. At the end of the year, you either get money back or had to pay for the excess consumption to the energy company.

EV chargers and modern digital metering systems allow one important thing: flexible energy prices. That means energy can cost more during the days than during the night. We can also think a step further, with energy having a different price every hour. Similar to the fluctuating stock market, for example. However, in most cases, we have something in between. Typically, there are 2-3 price points per day. This is what we call time-of-use rates (TOU rates).

Why are TOU rates important for EV charging? Well, let’s say you pay 10 cents per kWh at night and 30 cents per kWh during the day. It’s pretty obvious when to do most of your charging if you can, right? So we need to coordinate charging, so we reduce total charging costs by taking advantage of TOU rates.

Let’s consider a scenario where a vehicle arrives at 9 o’clock in the morning at the office. Let’s assume the energy company defines this as peak time where they charge 50 cents per kWh. So we delay the charging by 1 hour, and the price drops 30 cents per kWh to save cash.

Why do utilities use TOU rates? Well, it’s difficult to explain — in fact, it could be covered in an entirely new article!

The short answer is: for a similar as Demand Charges — to reduce the energy consumption when less energy is available (less sun or wind energy) or because the electric grid is busy with high demand.

C) Vehicle prioritization: Speed up the charging if vehicles leave earlier than others

vehicle prioritization challenges solved with smart charging software

Not every electric vehicle is the same. Instead, each vehicle or driver arrives with a certain set of requirements. That is true for public charging networks as well as private fleets of vehicles.

The two most relevant parameters for smart charging are: the planned departure time and the required energy amount (target SoC) of the vehicle.

A simple example is:

  • Vehicle 1: leaves in 4 hours and needs 50 kWh
  • Vehicle 2: leaves in 2 hours and needs 60 kWh

In an optimized charging process, vehicle 2 will get the priority. That could mean the vehicle receives a higher power from the charge point, or the vehicle can start charging earlier than vehicle 1 or similar. If the location has a mix of AC and DC chargers, smart charging could even schedule vehicle 2 to a fast DC charger to accelerate the charging process.

This optimization doesn’t consider the energy rate, maximum power capacity at the location, or demand charges. Instead, it is focusing solely on achieving a punctual departure with enough energy for the trip.

D) Combine multiple goals

Now, in most real-world cases, we see a mix of the possibilities mentioned above.

Typically, demand charges are mixed with TOU rates. And although public charging networks might care less about the prioritization of vehicles, it is the number one priority for most commercial fleet managers.

So, do we need a trade-off between these optimization goals? Do we need to pick one?


Intelligent software systems for electric vehicles have shown that optimization can achieve cross-functional optimization goals to reduce costs and increase the reliability of a charging network.

In fact, at Ampcontrol, we’ve developed these multi-goal optimizations that can easily be implemented in central charging systems (such as OCPP servers).

This allows you to reduce grid extension costs, avoid demand charges, reduce energy costs (per kWh), ensure an on-time departure, and ensure sufficient energy for individual trips. In addition, there are technically no limitations on how smart charging software works with OCPP or similar.

Technology basics

How to connect smart charging to OCPP systems?

Sequence Diagram: Starting and stopping a transaction on OCPP 1.6

Typically, charging point operators (CPO) use central charging management systems to communicate with their charging points. And in around 80% of the cases, the cloud systems use OCPP (Open Charge Point Protocol).

OCPP is a standard protocol that enables the communication between the back-office and chargers. It’s the foundation for many digital services such as payment, authentication, error management, and also smart charging.

With OCPP 1.6 and 2.1, you can send charging commands to EV chargers. This means you can remote control the charging sessions at any time - manually or automatically. This has been one of the most significant innovations in the charging world so far.

If you want to learn more about this, you can start by reading this article on using csChargingProfile messages in OCPP.

Sequence Diagram: Set Charging Profile with OCPP 1.6

How to connect vehicle data with smart charging?

Why and when do we need to connect vehicles?

Depending on your optimization goal when applying intelligent charging software, the software needs to identify the expected departure time and the state of charge (SoC) of each vehicle. This enables sophisticated and optimized EV charging. But, if you’re currently not able to get to this point, don’t worry.

If you plan to connect your intelligent charging software to vehicles, there are 3 possibles ways:

Firstly, you can use existing logging devices to stream data from the vehicle sensors to a cloud system. This can be pretty seamless. However, it doesn’t work for all auto brands or models. The good news is that these devices have been around for the past few years for classical fleet management.

Secondly, you can use telematics systems or cloud services from vehicle manufacturers to access your sensor data. More and more companies have been enabling this service, and this will likely continue. That means the vehicle has pre-integrated communication systems that send data with 5G, or similar, to a central cloud system from the manufacturer. Smart charging software like Ampcontrol can then monitor these data points. Again, there is no additional hardware required.

Thirdly, the vehicle can potentially communicate with the charge point. How? Through the electric cable. This is something that many charging station manufacturers and OEMs have collaborated on and is known as ISO 15118 standard. If the vehicle and charging station both have the required ISO 15118, the vehicle sends SoC data points to the charge point. Then, in a second step, the charge point sends the SoC data to the central charging system. Like many new technologies, it will take a while until every vehicle and charger supports this standard. Still, eventually, this will be the easiest way to access and communicate data quickly and easily.

cloud software seamlessly receives data from vehicle telematics and charger

How can you try out smart charging?

Now we covered the basics of intelligent charging technology; the next question is - how to get started?

The easiest and cheapest ways to start are simulations. That means you don’t go through the entire implementation right away. Instead, you test and analyze possible approaches virtually.

At Ampcontrol, for example, we typically define the smart charging goals together with customers and then set up a sophisticated simulation tool. This demonstrates the possible output of pioneer projects at scale.

A significant advantage of running simulations initially is that it can help challenge your assumptions and make changes. Making changes early in a project will save everyone time, money, and effort and should be the rule rather than the exception.

It is also important to note that simulations don’t have to be limited to assumptions. Great intelligent charging simulations can input actual historical data of vehicles and energy. This includes, for instance, arrival times, departure times, required energy, and more.

How to get started with smart charging?

We’ve covered the basics of smart charging technology, some use cases, and the advantages of running simulations for future smart charging.

Read more about smart charging and OCPP in our report: What Is OCPP and How to Use It for Smart Charging.

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