EV Fleet Charging Solutions For Your Depot

Companies need to base their commercial EV charging setup on when their vehicles return, how long they stay on site, and when they need to leave again. Each vehicle needs enough charge for its next route without the chargers demanding more power than your site can supply.

In this article, we explain what to consider when selecting an EV fleet charging solution for your depot, from how many chargers to install to how to plan for later expansion. We also look at how spare charging time may create an additional revenue stream.

How much charge does each vehicle need for its next route?

Work out how much electricity each vehicle needs for its next route and how long you have to get that electricity into the battery. Don’t rely on a daily average across the fleet. Nineteen of your vans may travel 60 miles a day while another regularly covers 180 miles and needs much more electricity before its next departure.

Start off with your route records. For each vehicle, look at:

• Distances travelled
• Loads carried
• Its return and departure times
• Electricity used by refrigeration, heating or other equipment

Also factor in winter weather or particularly demanding routes when estimating how much electricity each vehicle will need.

How do I estimate how much charge each vehicle will need before buying the EVs?

If you want to replace some or all of your ICE vehicles with electric vehicles, the best place to start is to work out how much charge each will need by using your existing journey records with consumption figures from the manufacturer.

Electricity use is measured in kilowatt-hours (kWh). For example, if a 100-mile route is expected to use 0.4kWh per mile, the vehicle will need about 40kWh for that journey.

You then need to work out how much of that electricity you’ll need to put back into the battery when the vehicle is at the depot. A vehicle that returns with 15kWh still in its battery needs less charging than one that returns almost empty.

Next, work out how long the vehicle can actually be plugged in. A vehicle may be at the depot for 12 hours but only available to charge for nine after unloading, cleaning or moving to a charging bay.

You now know how much electricity needs to go back into the battery and how long you have to put it there. Your installer can use those figures to work out the charger power you need.

Note: Your installer should also allow for electricity lost during charging, so the charger will need to supply slightly more electricity than the battery itself needs.

How powerful should your fleet chargers be, and how many do you need?

Now you know how much charge each vehicle needs, you can start designing a setup that works for your business. Every vehicle must have enough charge before it leaves your site without installing more equipment than the depot needs.

How powerful do the chargers need to be?

Charging power is measured in kilowatts (kW). If a vehicle needs 40kWh and you have eight hours to charge it, for example, you need to supply an average of about 5kW during that time.

Each vehicle will also have its own limits on how fast it can charge. If a van only accepts 11kW, a 22kW charge point will only deliver half of its maximum output.

You’ll also need to choose between:

• AC charging: Works well for vans and other vehicles that remain at the depot for several hours, like pool cars and minibuses parked overnight
• DC charging: Delivers electricity more quickly, so better for vehicles with shorter turnaround times or much larger batteries, like buses and HGVs

Whichever you select, your supplier should match up the AC or DC charging setup to the vehicles you plan to use.

When planning your EV fleet charging infrastructure, also remember that a charger’s advertised power is its maximum output and not a guarantee that this is what it will deliver constantly throughout a charging session. Ask your supplier to calculate how long your vehicles should actually take to charge.

How many charging points do you need?

Next, work out how many vehicles need to be plugged in at the same time.

Giving every vehicle that stays overnight its own charging connection means staff do not have to move vehicles or swap cables during the night. You may be able to use fewer connections if vehicles return and leave at different times and someone may be able to move vehicles between charging points when needed.

Then check what each connection can actually deliver. Some chargers split their total power between two outlets. If a charger has 22kW available in total and two vehicles plug in at once, they may have to share that 22kW between them, meaning each vehicle may receive only 11kW if the power is split evenly.

Finally, check the depot layout. Cables need to reach the charging sockets, and the bays still need enough space for vehicles to load, unload, turn and leave safely.

How much power can your depot spare?

Before deciding how much power the chargers can use, check how much power the rest of the depot needs while the vehicles are plugged in. Your site may need to power refrigeration, heating and warehouse machinery at the same time. With hotel EV charging, guest chargers may be drawing power at the same time as kitchens, laundry, heating and cooling.

Your electrical designer should check how much power your site is allowed to take from the grid and how much key equipment like the transformer, circuits and switchgear can safely handle. They’ll then have the information they need to work out how much is left for charging.

Give them a full year of meter readings. If you don’t know where they are, check your electricity supplier’s online account or ask the supplier for them.

They can then run half-hourly data analysis to work out how your electricity use changes through the day and year. That shows them when the rest of the depot is likely to need the most power. If you have readings taken more frequently than every half hour, that’s helpful too, as they can show brief spikes in demand.

Tell them about any equipment you plan to add too. Every new piece of machinery, heating system or other electrical equipment could mean you have less power for charging. If you have solar panels or a battery, tell the designer about those as well because they can supply some of the power your depot needs while the vehicles are charging.

Your connection paperwork may show your limit in kilovolt-amperes (kVA) rather than kilowatts (kW). Ask your designer to tell you how much charging power you can actually use after allowing for the rest of the depot.

Can managed charging get every vehicle ready?

Managed charging is a way of controlling how the power you make available for EV charging is distributed between vehicles that are plugged into the system.

You can prioritise vehicles that need to leave sooner and reduce the power going to those staying at the depot for longer, while keeping total charging demand within your site’s limit.

To do that, give your EV charging management system enough information about each vehicle, including when it needs to leave and how much charge it needs. The system can then adjust the chargers to follow those priorities.

There are limits to what managed charging can achieve, though.

For example, a vehicle needing 40kWh before it leaves the depot may only be able to receive 28kWh in the time available, even if you give it priority. You would need more charging time or a higher compatible charging rate.

Can 20 vans charge overnight with 100kW available?

Suppose 20 vans plug in at six in the evening and need to leave at six in the morning. Each needs 36kWh added to its battery. If, for this example, 90% of the electricity supplied by the charger reaches the battery, each charger needs to supply 40kWh.

Each van has its own 7kW AC charge point, but the depot only has 100kW available for charging after the rest of the site has taken the electricity it needs.

All 20 vans could still be ready by 02:00 if the available 100kW were shared at 5kW per van. That works because every van has the time to receive the 40kWh it needs in full.

Now suppose one van needs to leave at 10 at night instead. Even if you give it priority on the system, its 7kW charger can supply only 28kWh in the four hours available, so it’s 12kWh short.

While the depot has enough electricity to charge the fleet over the full night, that particular van does not have enough charging time to get up to the charge level it requires before it leaves.

In this case, the solution would be a longer charging window, a faster compatible charger or a different vehicle for that route.

Can your fleet chargers earn money while vehicles are plugged in?

You may be able to. If your vans are parked at the depot for 12 hours at night, for example, but they only need six hours to get the charge they need, you don’t have to start charging them all up the moment they arrive. Some can charge later and they’ll still be ready well in time for when your drivers need them.

Here’s a walkthrough of how it works.

Example: 12 vans plugged in overnight

Let’s say that 12 vans return to your depot at six at night and leave again at six in the morning. Each one needs 30kWh of charge before it goes back out, so you need 360kWh to power the fleet:

12 vans × 30kWh = 360kWh

Each of your vans can pick up its 30kWh by charging at 5kW for six hours. As the vans will be plugged in for 12 hours, that means you have, in effect, six hours of spare charging time.

Suppose that your 12 vans usually charge at 5kW between 18:00 and 20:00. Together, their chargers would draw 60kW:

12 vans × 5kW = 60kW

There may be a chance to earn money from a flexibility service at this point.

People often call this the flexibility market, although it’s really a group of different services. They pay businesses that can change how much electricity they take from or send to the grid at a particular time.

For example, NESO or your local network operator may need businesses to use less electricity for an hour or two when there’s a lot of pressure on the grid.

In this example, you wouldn’t be selling electricity from your vans. You’d agree to pause or slow down some of their chargers for two hours, then switch them back on later.

Provided everything else at your depot carried on as normal, your meter would record that your depot took less electricity from the grid during those two hours. The provider would then use the meter reading and the rules of the service to work out how much you should be paid.

In this example, your control software, such as GridVolt, pauses eight of the vans and leaves the other four charging. The power going to the chargers falls from 60kW to 20kW.

That’s a 40kW drop for two hours:

60kW − 20kW = 40kW

40kW × 2 hours = 80kWh

At 20:00, your eight vans start charging again. They still have ten hours before they leave, so every van can receive the full 30kWh it needs.

You haven’t used any less electricity by the end of the night. All you did was wait two hours before you started charging those eight vans again. If your depot qualifies and follows the service rules, you may be paid for waiting.

They work out how much by comparing your meter readings with the “baseline”. This is what they estimate you would have taken from the grid if you hadn’t taken part in the flexibility event. In this example, the difference is 80kWh.

Suppose, purely to show the calculation, that the service paid £1 for each kWh by which you reduced your grid use. The payment for the event would be:

80kWh × £1 = £80

If you did the same thing 20 times in a year in response to requests from NESO or your local network operator, you would receive £1,600 before fees and any other costs:

20 events × £80 = £1,600

The £1 rate and the 20 events are illustrative and you shouldn’t base an investment decision on them. They’re here to show you how the system works.

You may also save money on your electricity bill. Say that you would have paid 30p per kWh between 18:00 and 20:00 but only 15p later that night. By waiting, you would save 15p on each of the 80kWh:

80kWh × 15p = £12

This is also an illustrative example you shouldn’t base an investment decision on.

You can’t assume that you’ll receive the flexibility payment and make the bill saving on the same 80kWh. Whether you can get both depends on your electricity tariff, flexibility agreement and the rules of the service.

On days when vans need to leave at different times, like one at nine in the evening, the software would leave that van charging if it still needed more electricity for its route.

What if the connection is still too small for EV fleet charging?

If you don’t have enough power for EV charging, work out how long you’re short of power for. It might only happen during short busy periods, or you could be short for several hours when most of the fleet is charging.

Look at your charging schedule first. You may be able to plug some vehicles in earlier or keep them connected for longer. For non-essential depot equipment like vehicle washing equipment and workshop machinery, run them at a different time so there’s more power available for the chargers.

Commercial battery storage can help if you only need extra power for short periods. It can charge when your site has spare capacity and supply some of the power the chargers need later. This can reduce the peak power you take from the grid, which is a form of peak shaving.

But a battery cannot solve every connection problem. If your site doesn’t receive enough electricity in general, you may simply shift the shortage from one part of the day to another. When a battery stores electricity earlier and supplies it later because the chargers need more power than the grid connection can provide, this is battery buffered EV charging.

Solar can help if your vehicles are charging while the panels are generating. Use winter as well as summer figures, and check whether the vehicles are actually at the depot when that solar power is available.

If you still cannot give every vehicle enough charge, you may need a larger grid connection or to electrify the fleet in stages. Your installer should compare both options using the same routes, charging times and site electricity use.

Build a plan for charging failures

Decide how staff should react if a vehicle has not charged enough or part of the charging setup, like a charger or the internet connection, stops working. Ideally, you should agree who will do what before installation begins.

Ask your installer whether any chargers share the same power supply, circuit or control equipment as a single fault could stop multiple charging bays working at once.

During the commissioning stage, test what happens if:

• A vehicle has not charged: Decide who receives the alert and whether they move the vehicle to another charger or use another vehicle for the route.
• A charger stops working: Agree who reports the fault, how quickly someone will respond and which other charger the vehicle can use.
• The internet or charging software fails: Ask what the chargers will do until the connection comes back. Any charging that continues must still stay within the site’s electrical limits.
• The grid power goes off: Find out whether the chargers stop or can use backup power. If you expect a battery to keep them running, tell your installer when the system is designed. A battery installed for other purposes will not automatically provide backup power.

Put these responsibilities and response times in your support agreement, including who staff should contact when something goes wrong.

How should you compare EV fleet charging proposals?

Give each supplier the same information about your fleet, including the routes your vehicles run, when they return and leave, how much charge they need and how much power your depot has available.

The cheapest quote may cost less because there is no spare charger if one fails. A more expensive one might include a spare charger or electrical work sized for the next phase of your fleet rollout.

Get a full breakdown of what you’ll pay for the chargers, electrical work, grid connection work, cabling and groundworks, controls and software. Add maintenance, replacement costs and any extra staff time if they are not already included.

Compare running costs using the same routes, charging times and electricity prices. A quote based mainly on cheaper overnight charging will look better than one using daytime prices, even though they are based on different assumptions. Include charging losses too because you will pay for slightly more electricity than reaches the batteries.

When a supplier says its setup will save you money, ask them to show exactly where the saving comes from. It might be lower electricity costs, fewer chargers, less electrical work or avoiding some grid connection work. Compare those savings with any extra upfront or running costs before choosing a depot charging solution.

Roll out in stages and measure the result

You do not have to electrify the whole fleet at once. Starting off with a smaller group of vehicles gives you the opportunity to find out whether the charging setup works before you add more.

Include some of your harder routes and busier days in the first stage. A good test of your chargers will be using them on vehicles that often return late or need more charge than usual.

Even if you install fewer chargers at first, ask your installer to plan the cabling, electrical equipment and space you will need later. Check the power available for each new stage rather than assuming the depot can support it because the first stage worked.

Before the vehicles go into normal service, get your installer to test the chargers with the vehicles and equipment you will actually use. Then keep a record of:

• Whether each vehicle leaves with enough charge
• Which charging sessions start late or fail
• How much electricity the chargers use
• How often staff have to step in to get a vehicle charged on time

Use what you learn from the initial rollout to make changes to the charging setup or the way vehicles are scheduled before adding the next group of vehicles. Time your expansion so you only add more vehicles once the first stage is working reliably and you know there is enough power for them.

See how EV charging could fit with the rest of your depot

If you are adding EV charging to a depot with solar, battery storage or other large electrical loads, GridVolt Energy Manager can control compatible EV chargers alongside that equipment. It uses site electricity data, your tariff and forecasts of demand and solar generation to decide how connected equipment should operate.

Give us the details of your chargers and any battery, inverter or existing control software, along with information about your site’s electricity use. We can check what Energy Manager can connect to and explain how EV charging could be controlled alongside the rest of the site.

If your vehicles have spare charging time, let GridVolt discover if you’re eligible for income from wholesale and flexible markets, and work out how much you can earn without disrupting charging to your vehicles.

To find out more, fill out the form on the right, or get in touch with us via our contact page.

FAQs

Can you install fleet chargers at a leased depot?

Yes, subject to your lease and any required landlord consent. Before committing to the installation, agree who owns the equipment, who can access it for maintenance and what happens when the lease ends.

Can different vehicle brands use the same depot chargers?

Yes, if the vehicles use compatible charging connections and can charge from the equipment you install. Check the charging limits of each model rather than assuming every vehicle will charge at the same rate. If you use managed charging, ask the supplier to confirm that the system can work with every vehicle model in your fleet. A connector that fits does not necessarily mean every charging-management function will work.