When planning an electric fleet depot, it’s tempting to start with the chargers. How many do you need? Should they be 60kW, 180kW or higher? Standalone units or a distributed system?
But the first question you should actually be asking is more basic: how much electrical capacity can the depot use?
Buy chargers before checking site capacity, and you risk delayed connections, unplanned infrastructure costs or a charging schedule that simply cannot keep up with daily fleet operations. On the other hand, simply adding up the maximum ratings of every charger can significantly overstate what the fleet actually needs.
Before committing to any charging equipment, operators need a clear picture of three things: the depot’s existing power supply, the fleet’s real energy requirements and the charging windows available each day.
1. Establish the Depot’s Existing Electrical Capacity
Start by working out how much power is already available on site and how much of it is already being used.
Useful information to pull together includes:
- The site’s existing electricity connection and agreed capacity
- The MPAN and details of the current electricity supply
- At least 12 months of electricity bills
- Half-hourly consumption data, where available
- The site’s recorded maximum demand
- Existing loads from lighting, heating, ventilation, warehousing or industrial equipment
The gap between the site’s agreed capacity and its existing peak demand gives you a first indication of how much power might be free for EV charging.
That said, do not treat this figure as a final design limit. Existing loads shift with the seasons, time of day and production schedules. Planned expansion, a switch to electric heating or new machinery coming online can all compete with the chargers for the same headroom.
A proper depot power assessment needs to account for current consumption as well as where operations are heading.
2. Build a Fleet Charging Load Profile
Once you understand the existing supply, the next step is working out what the vehicles actually need.
A fleet charging load profile should answer a few practical questions:
- How many vehicles return to the depot each day?
- How much energy does each one use on its route?
- What battery level is it likely to return with?
- When does it arrive?
- When does it need to leave again?
- Which vehicles have the tightest charging windows?
- How are routes and fleet size likely to change over time?
A simple starting calculation looks like this:
Average charging power required = Total fleet energy required ÷ Available charging window
A fleet that comes back in the evening and remains parked overnight has several hours to recover its energy. A bus or truck that needs to turn around quickly does not have that luxury and will need a much higher charging rate.
The average figure on its own is not enough to finalise a system design. You still need to factor in staggered arrival times, route changes, charging losses and vehicles that leave earlier than scheduled.
Even so, it is a far more useful starting point than simply choosing chargers based on their maximum advertised output.
3. Don’t Just Add Up the Charger Ratings
Ten 180kW charging points do not automatically mean you need a continuous 1.8MW supply.
To get a realistic view of fleet depot power requirements, it helps to separate three figures:
- Installed charger capacity: the combined rated output of all the charging equipment.
- Maximum coincident demand: the highest power the chargers are likely to draw at the same time.
- Daily energy requirement: the total energy that needs to go into the vehicles before they leave.
The goal is not to run every charger at maximum output throughout the night. It is to make sure every vehicle has enough energy before its next shift or route.
If vehicles arrive at different times with different battery levels and departure priorities, their demand will not all peak simultaneously. Modelling that behaviour gives a more realistic picture of the grid capacity the depot actually needs.
It also helps answer another practical question: should power be permanently assigned to individual chargers, or shared across the depot?
This is why fleet charging throughput can be a more useful planning metric than charger quantity alone.
4. Speak to the DNO Before Locking In Equipment
If it is not clear that the existing connection can support the expected load, contact the local Distribution Network Operator, or DNO, early.
The DNO is likely to ask for:
- The site address and existing connection details
- Current and historical maximum demand
- The proposed additional charging load
- Charger and electrical equipment specifications
- The expected commissioning date
- Details of future expansion phases
From there, the DNO can assess whether the existing connection can support the proposed project or whether reinforcement, a new connection or another arrangement may be needed.
This conversation should happen before the equipment and project schedule are locked in. Connection requirements can affect available power, project cost, charger choice and delivery timelines all at once.
The UK government provides an overview of the process for connecting EV chargepoints to the electricity network, while the Energy Networks Association has published separate guidance for connecting transport assets to the grid.
No charger supplier or charging software can promise that a DNO upgrade will not be required. That answer depends on the local network, the site connection and the fleet’s actual demand.
If the review shows that the existing connection cannot support the proposed charging demand, the next stage is to prepare the DNO connection application.
5. Consider Managed Charging and Shared Power
When site capacity is tight, a larger fixed supply is not the only route forward.
Managed fleet charging schedules charging around when vehicles arrive, how much energy they need and when they have to leave. Vehicles departing first can receive power earlier, while vehicles with longer dwell times can charge later or at a lower rate.
A shared power charging system takes that a step further by allocating available power dynamically across multiple charging outputs, rather than reserving a fixed amount for each charging point regardless of what is happening.
Once one vehicle’s demand drops or it finishes charging, that released capacity can be directed to another connected vehicle. This reduces stranded capacity and makes better use of the power the site already has.
The Injet HanYuan distributed charging system uses a centralised Power Pool architecture built around 40kW power module granularity. This allows available power to be allocated across connected charging outputs based on the system configuration and vehicle demand.
If you are comparing this approach with standalone chargers, our guide to distributed charging systems explains how central power cabinets, charging dispensers and shared power allocation work together.
There is one important limitation:
Managed charging and shared power can reduce coincident peak demand, but they cannot reduce how much total energy the fleet needs.
If the vehicles need more energy than the connection can deliver within their parking windows, the depot may still need additional grid capacity, longer charging periods or other energy infrastructure. No amount of scheduling can remove the underlying energy requirement.
6. Plan for Fleet Expansion, Not Just Day One
Do not design a depot around only the first group of electric vehicles.
Fleet numbers grow, larger trucks or buses may be introduced, and new routes can create tighter charging windows. A design that leaves no room for additional cables, power modules, dispensers or electrical equipment may need expensive rework later.
A phased plan should cover:
| Project stage | Information to confirm |
|---|---|
| Initial deployment | Vehicle numbers, routes, daily energy and charging windows |
| Fleet expansion | Expected vehicle additions and increased energy demand |
| Long-term operation | Larger vehicles, shorter dwell times and new charging requirements |
That does not mean building the full long-term system on day one. It means making early decisions with future expansion already in mind.
For a distributed charging system, expansion might involve adding dispensers, power modules or further cabinet capacity. For standalone chargers, it may require additional chargers, distribution circuits and switchgear capacity.
Either way, future grid demand needs to be part of the site plan from the start. Our guide to scaling fleet depot charging without rebuilding the entire system looks at this expansion question in more detail.
Fleet Depot Grid Capacity Checklist
Before buying fleet chargers, make sure you have covered the following:
- Existing supply and agreed capacity identified
- Historical electricity consumption collected
- Site maximum demand understood
- Vehicle arrival and departure times recorded
- Daily fleet energy requirements calculated
- Coincident charging demand modelled
- Local DNO contacted where necessary
- Managed charging and shared-power options evaluated
- Future fleet phases included
- Charger architecture selected after the power assessment
Assess the Depot Before You Pick the Chargers
The highest-powered charger on the market is not automatically the right one for your depot.
The right system comes down to how much energy the vehicles need, when they are available to charge and how much power the site can provide. Get those three things clear first, and comparing standalone chargers, distributed charging and managed charging becomes a much more grounded exercise.
In short, the order should be:
- Analyse vehicle routes and daily energy demand.
- Confirm the depot’s existing electrical capacity.
- Model the expected coincident charging load.
- Discuss the proposed connection with the DNO.
- Select the charging power, equipment quantity and system architecture.
Work in that order, and you reduce the risk of buying equipment the site cannot fully use while leaving a clearer path for future fleet expansion.
For the wider planning process, including charger selection, site layout and operational requirements, read our fleet EV charging infrastructure guide for UK commercial depots.
Next Step: Turn the Capacity Review Into a DNO Application
Once the depot’s existing headroom and future charging demand are understood, the project team can define the connection requirement.
If the site needs additional capacity, the application should be supported by a clear maximum import request, a time-based charging load profile, site plans and the relevant charger input data. These details give the DNO a more realistic basis for assessing the proposed connection and identifying whether network reinforcement may be required.
Read DNO Application for EV Charging Depots in the UK for the full process, ENA’s role and the information a fleet charging project should prepare.
Button: Read the DNO Application Guide
Link: https://injetcharger.co.uk/news/dno-application-ev-charging-depot-uk/
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FAQ
How much grid capacity does an EV fleet depot need?
It depends on the number of vehicles, their daily energy consumption, the charging windows available and how many need to charge at once. Adding up the maximum rating of every charger can overstate actual demand. A proper fleet charging load profile is a more accurate starting point.
Do I need a new grid connection for fleet EV charging?
Not necessarily. Some depots can work within their existing connection, especially where vehicles remain parked for long periods or charging can be actively managed. Larger fleets and high-power charging projects are more likely to need an upgraded or new connection, so it is worth consulting the local DNO before locking in equipment.
What information does a DNO need for a fleet charging project?
The DNO may ask for the site address, existing supply details, current maximum demand, proposed charging load, relevant equipment specifications and the expected project timeline. A phased forecast can also help show how electricity demand is likely to grow as the fleet expands.
Can managed charging avoid a grid upgrade?
It may help by reducing simultaneous peak demand and scheduling vehicles around their energy requirements and departure times. However, it does not reduce the fleet’s total energy requirement. Whether it can avoid or delay an upgrade depends on the existing site capacity, charging windows and how the fleet operates.
What is the benefit of shared power in a fleet depot?
Shared power allows available charging capacity to move to where it is needed, rather than permanently reserving a fixed amount for each charging point. This reduces stranded capacity and directs more power towards priority vehicles while keeping total charging demand within the configured site limit.
