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Assessing an EV charging site for battery energy storage: What to expect

Nigel Dent, Head of Sales, at Connected Energy, explains the steps we take to model EV charging sites for battery energy storage.


When making any significant investment in new technology, it’s important to fully understand what benefits it can bring, and why.

Site surveys and data modelling can demonstrate the potential for battery energy storage systems in a variety of applications. This is vital for those looking at installing high-capacity chargers, in understanding how a battery energy storage system (BESS) can make their lives easier by solving some of the biggest challenges around vehicle electrification.

For example, truck dealerships, rapid hubs and fleet depots will all need high-capacity electric charging points to support the transition towards larger batteries and high powered vehicles such as trucks, buses and HGVs. But how do they know if their local grid connection can support such a big user of energy? Connected Energy can help with feasibility studies to show you how much power your site uses now, how much headroom the grid can offer you, and what to do if you need more electricity than the grid can provide.

1. Current usage

The first thing you can expect us to ask is for data on the overall site’s current energy usage – ideally half-hourly data covering a full year. This enables us to identify the maximum amount of power currently needed and establish a usage pattern.

2. EV charging needs

Once we have established that baseline, we’ll ask for information about what types and sizes of EV chargers you want on site, for example is it a high-capacity charger for trucks, and if so, is it a 150 kilowatt or 350kW unit? Do you need more than one? Do you also want electric van or car chargers on site? We’ll also ask about how you intend to use the charge points – for example, will you be using them more at certain times of the day, or are you generally intending to plug in to recharge overnight?

3. Import capacity

The other piece of the puzzle that is vital if we want good results is your maximum import capacity (MIC) – this is included in your contract with your energy supplier and is the upper limit on how much energy you’re allowed to draw down from the grid. If you exceed your MIC – sometimes also known as a KVA allowance – you’re liable to face expensive surcharges on your energy bills.

In many cases, there simply isn’t any additional headroom from the local grid connection, meaning that you couldn’t get the power you’d need for these charge points without paying for the grid to be upgraded.

This is largely because when existing depots or dealerships were built, no one anticipated that the occupants would need hundreds of kilowatts of power. Before EVs came along they had relatively low energy demands – more than enough to cover lifts, power tools, roller door motors and the basics like heating and lighting.

4. Putting it altogether

Once we have these three data sets, we can very quickly identify any pain points – for example, if your MIC is 100kW, and your peak usage is 50kW, you could install a 50kW charger without going over your limit. However, if you’re looking to add a 150kW charge point on site, you’ll be in breach of your MIC by 100kW.

5. Finding the right solution

If you don’t have enough headroom on site to accommodate a high-capacity charger, Connected Energy can help you explore the option for battery energy storage. A BESS acts as an energy reservoir, drawing down power from the grid during quiet periods, then releasing it as required, such as for powering a truck charge point.

By adding a BESS into the mix, our modelling software can compare the savings to paying for an expensive grid upgrade or being hit with costly MIC surcharges.

6. Return on investment

Truck operators and dealerships will need to install high-capacity chargers sooner or later. Where Connected Energy can help is by ensuring that you add the charging infrastructure you need at the best possible price.

However, there are also opportunities to use your BESS to generate additional revenue, meaning it can deliver a better ROI. New initiatives like National Grid’s Demand Flexibility Service actually pay businesses for reducing their energy consumption during peak periods in winter when demand on our grid is at its highest. A BESS can help you participate in these schemes, generating an estimated £15,000 – £20,000 a year in extra income. Our feasibility studies can also help to calculate those returns.

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