Ask the Experts – What Is EV Charging Load Balancing?

Overview

As the demand for fleet charging grows, many organisations are finding that their premises and depots are simply not designed to cope with the number of EV chargers they need. This is because local grid infrastructure was not designed or built with EV charging en masse in mind.

In this blog, Paul Winchester, Director of Fleet Services at Mer, discusses:

• Why load balancing is necessary
• How load balancing is an innovative alternative to a DNO upgrade

Energy restrictions are causing delays to EV charging installations

We are seeing increasing enquiries for help to overcome energy capacity restrictions. Typically, these premises are older, meaning they do not have the infrastructure required to support lots of EVs – because EVs did not exist when these sites and depots were designed and built. No one envisioned the energy demands of electric vehicles.

When EVs charge, they pull a full charge for as long as they possibly can. If you have quite a few vehicles charging at once, this can cause problems. Even if you have five, ten or twenty charge points you are consuming quite a lot of energy.

The traditional way to get more power was to pay your district network operator (DNO) to upgrade your local infrastructure.

You can get a DNO upgrade, but there is a cost to this, and it can also take a long time – several months is not uncommon.

What is load balancing?

Whilst future proofing with a supply upgrade is still a sensible option, load balancing is an alternative way to unlock more fleet and depot EV charging capacity on site without an upgrade to your local electricity grid.

Load balancing enables you to put more charge points on site at a lower cost than a DNO upgrade, so it gives you the flexibility for expansion. At Mer, we can offer load balancing as an upgrade as and when you need it, you don’t have to install it when you install your first charge points. Your site does not need to be all singing and all dancing from day one.

For example, on a 22kW dual AC charger with two sockets, if two vehicles plug in, each vehicle will get 11kW (if the vehicles are capable). All the hardware required is already embedded in Mer’s smart chargers, meaning this is a very cost-effective option. This is load balancing at its most basic, but it can also handle more complex requirements.

With load balancing, you can connect 100 charge points on one system.

How to build a network

If you have a bank of smart charging points, Mer can take this to another level, by connecting them together to create a smart charging network. The network understands how much power is available in total. The chargers communicate with each other and automatically ramp up and down how much charging they are giving to vehicles, to stay under that limit.

If your site reaches the point that if all charging sockets are in use there is not enough power to feed all the vehicles at once, then they all start alternating. For example, unit one stops while units two and three charge their vehicles, then two stops while one and three charge, and so on.

Certain EVs charge at different rates to others. For example, some Renault models will only take a charge above a certain amperage. The charge point will identify that it has a Renault plugged in, communicate this to the rest of the network and ensure that it gets the right amperage to ensure the vehicle charges.

An example of this can be seen in our work with East Devon District Council’s EV fleet, where the introduction of load balancing helped to improve efficiency by dividing power between its vehicles.

Dynamic loads

A lot of EV charge points are located on buildings or sites that have other power requirements – for example, an office uses energy for lighting and powering computers; maybe it has escalators or elevators as well. This is what is known as an active or dynamic load because it constantly changes. Telling a smart charging network that the limit is 100A would be inaccurate because one second there might be 105A available and the next it might only be 95A.

In these circumstances, we would recommend nominating one of the charging points as the master unit and connecting it to your building management system (BMS), energy management system (EMS), a smart meter or CT clamp. In this way, the charge point network gets real time updates about the power parameters in which it must work. The network can then ramp up or down based on the live data from the BMS.

Renewable energy

If you have energy storage and renewable energy generation on site, such as a solar PV array, then you can use dynamic load balancing to integrate them with your charge point network.

By linking the network to an EMS or BMS you can instruct the charge points to draw energy from those renewable sources. It is all about using technology to create a more holistic approach to energy generation, usage and management.

Future proofing

While you might not need load balancing on site yet, it is only a matter of time. The transition to an electric fleet is underway and the number of drivers needing to charge their vehicles at a depot or workplace will incrementally increase year on year. By choosing Mer smart chargers, you have the flexibility to turn on load balancing in the future.

Customers appreciate having this flexibility. Fundamentally, it is about future-proofing your sites so you are ready for the changes that will inevitably come down the line.

At Mer we are experts helping our customers in planning, installing and maintaining EV fleet charging infrastructure, and we are happy to share our expertise to help you on the road to net zero. Our belief is that you shouldn’t have to be an energy expert – that’s our job.