Depot charging means charging vehicles at a central site the operator controls, usually overnight or between shifts, rather than relying on public chargers scattered across a route. For bus, HGV, and logistics fleets, it's the default model: the vehicles already return to one place every night, so that's where the charging infrastructure goes.
Central Charging, Not Public Charging
Public charging is built for occasional, unpredictable top-ups: whoever arrives first gets the next free bay. Depot charging is the opposite. The operator knows exactly which vehicles will be there, when, and for how long, which means the whole site can be engineered around a known duty cycle rather than guesswork.
That predictability is what makes depot charging cheaper per vehicle at scale, but it also means the infrastructure has to be sized correctly up front. Undersize it and vehicles don't get enough energy overnight. Oversize it and the grid connection becomes the single biggest, and most avoidable, cost on the project.
What a Depot Actually Needs
Three things determine whether a depot charging project is straightforward or expensive: how much energy the fleet needs per day (in kWh), how long the charging window is between shifts, and how much grid capacity is available on-site. The gap between what's available and what's needed is usually closed one of two ways: a grid connection upgrade through the local DNO, which can take 18–24 months and cost £200k–£400k, or dynamic load balancing across bays, which lets more vehicles share the existing supply without every charger running at full power simultaneously.
Depot, Overnight, and Opportunity Charging
These three terms get used loosely, but they describe genuinely different strategies:
| Model | When it charges | Best suited to |
|---|---|---|
| Depot charging | Any time the vehicle is at base | General term for all base-site charging |
| Overnight charging | Overnight, long low-power window | Fixed routes, predictable return times |
| Opportunity charging | Short high-power bursts during the day | Vehicles that can't finish a duty cycle on one charge |
Most fleets end up running a mix: overnight charging as the baseline, with opportunity charging at the depot or on-route to cover the vehicles running the longest or most demanding duties.
Where Neutron Fits
Our Master Units and modular group charging systems are built specifically for the depot model: one power distribution point feeding multiple bays, with load shared dynamically so a site can run more vehicles on a given grid connection than a one-charger-per-bay layout ever could.
What's the difference between depot charging and opportunity charging?
Depot charging happens at a central base, usually overnight or between shifts, on infrastructure the operator owns or leases. Opportunity charging happens in short bursts during the working day, at the depot or on-route, to top up a vehicle that can't complete its full duty cycle on one charge.
How much grid capacity does a depot need for EV charging?
It depends on fleet size, vehicle battery capacity, and the charging window available, but the number that matters is peak simultaneous demand, not the sum of every charger's rating. Dynamic load balancing typically lets a depot run well below that theoretical peak, which is usually the difference between fitting inside an existing grid connection and needing a costly DNO upgrade.
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