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Pekka Tiainen

Multi-Level Load Balancing with OCPP

At a Crossroad: Open Path or Vendor Lock Lane?
At a Crossroad: Open Path or Vendor Lock Lane?

Charging systems are currently being deployed "everywhere", but all the necessary information is not always available when the first charge points are being installed. Even in smaller systems, it's crucial to understand what it means when the system expands or changes. If this is not considered in time, it could mean that the initial choice of chargers and backends dictates the equipment choices for the coming decades. A management system is much more than just a billing system, and Wattery is not just a billing system.


In this post, I'll cover the following important topics:


  • What is OCPP and why is it important?

  • Why should chargepoints support load management via OCPP?

  • How is load management implemented with OCPP?

 


What is OCPP and why is it important?

OCPP stands for Open Charge Point Protocol, which is an open data transfer protocol for controlling charge points. "Open" means that the data transfer is not tied to any specific hardware manufacturer or management system, allowing charge points to be controlled regardless of the manufacturer. This means that you can use devices from different manufacturers in the same charging network. This may not always be optimal for maintenance or operations, but it's important to know that if a charger or manufacturer is not available in the long term, it can be replaced with another device.


OCPP transmits charger data to a central server (or in some cases a "master" charger), containing user identification, consumption data, load management, fault information and much more. As of this writing, the most common version of OCPP in use is 1.6, but 2.0.1 is already on the horizon. Key new features in OCPP 2.0.1 from a consumer perspective include the ability to use Plug-And-Charge and bidirectional charging (V2G).


OCPP can be implemented with direct connection from the charger or through a proxy to the management system. If the charger is directly connected to the management system, the system's OCPP address is set in the device settings, and the charger connects directly to the back-end. If a "proxy" is used, the the charger connects to the manufacturer's own OCPP (or similar) cloud service, which then provides an OCPP interface for the back-end system. In the case of a proxy, the operator is dependent on the manufacturer's cloud service. If there is a maintenance break in the cloud service, the operator is also affected. If the cloud service is discontinued... then there's something to think about for all parties involved. Unfortunately, we have these discussions, if not weekly, then several times a month.

 


An open charging system is future-proof
An open charging system is future-proof

Why should the charge point support load management with OCPP?

Load management is an optional module in OCPP called "Smart Charging." It's important to recognize and ensure that the chargers supports this as to avoid being tied to the manufacturer's load management. If a chargers load cannot be controlled via an external OCPP server, load management always occurs through the manufacturer's own systems, whether it's local or through a cloud service. The likelihood that a competitor's devices can be connected to the manufacturer's load management system is small, as manufacturers' main goal is to sell their devices. Always ensure before selecting a management system whether the load management is done through the manufacturer's system or if it is open.


You need to ask yourself:

  • What if the manufacturer doesn't exist in ten years?

  • What if another manufacturer decide to slash prices, can you connect this to the same load management?

 

 


Multi-level load balancing can be a challenge
Multi-level load balancing can be a challenge

How is load management implemented with OCPP?

In addition to openness, the technical features of the system must be considered in implementing load management. When load management is appropriately sized, it can prevent major electrical changes (i.e. costs). This of course, isn't always possible, and the older the property, the more likely there will be bottlenecks to address, but it's advisable to turn to a professional who has implemented charging systems to find these bottlenecks.


In designing load management, consider all levels from the main supply line. If any current other than charging current passes through a protective device/fuse, an external meter should be installed for dynamic load management. If there is only charging current passing through the protective device, a software based static restriction can be used, which distributes the available capacity among the chargers.


With Wattery's load management, an unlimited number of levels can be implemented, which can be either dynamic or static. You can find implementation examples on our website under "Resources", and we encourage designers and contractors to contact us in the system design phase.


For example, through a 63A fuse, a 12-hour overnight charge can deliver enough energy for ten cars to drive an average of 240 km each. If one car charges less, then the next car can fully charge their battery. The likelihood that four cars will charge with low state of charge is higher, which is why the power per space needs to be set to 5.5 kW, or 330 km per spot per 12 hours.


Guideline fuse sizes and spot counts:

Main fuse (A) Number of spaces Power per car (kW)

32 4 5,5

63 10 4

125 28 3

250 70 2,3

 

These are guidelines and are always applied case-by-case.

 

 


Wattery makes your life easier
Wattery makes your life easier

At Wattery, we require that all chargers can be connected directly to our server and that they support load management via OCPP.


Technically, chargers can be connected to Wattery via a proxy without load management or with the manufacturer's load management, but we have made a principled decision not to support this.


Why? You will lose certain manufacturers and thus customers.

Yes, but we see that openness is more important.


You must understand that the customer is always somewhat bound to a system. In the case of Wattery, this commitment means only the startup fee. If dynamic load management is implemented, then there is a little bit more to this. The rest of the system is built with open components: OCPP and Modbus. This is, however, a much smaller price than if ten chargers are installed at 2,000 € each, and you are committed to a specific system.


Life is just a series of choices, and at Wattery, we want to make your choices for charging systems safe and easy. We have extensive experience in implementing charging systems, and we can help you make open and technically sound decisions. There has to be an overall vision of the charging system.


Wattery is not just a billing system.



Contact us at the start of your project, and let us together make it a success. This is why we exist.



-Pekka


+358 (0)10 582 1000


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