The power problem
A diesel delivery van runs at the depot for a few minutes between shifts to refuel. An electric delivery van needs to plug in for 6 to 12 hours to fully charge from depleted. Multiply that by 20, 50, or 200 vehicles and you have a building that suddenly wants megawatts of capacity at night when no one else is using power.
The good news: nighttime is when utility rates are lowest, so the math works if you do it right. The bad news: the utility service entrance has to handle the new load, and that often means a service upgrade or a new utility transformer.
Step 1: load math
Fleet charging design starts with the load profile. How many vehicles, how big are their batteries, how much energy do they use per shift, and what is the charging window between shifts?
A class 4 to 6 delivery van with a 150 kWh battery that runs 100 kWh per shift needs 100 kWh delivered between shifts. If the charging window is 10 hours, that is 10 kW per vehicle continuous, which is roughly a 50A Level 2 charger.
A class 7 to 8 truck (regional haul) with a 500 kWh battery that runs 400 kWh per shift on a 12-hour window needs 33 kW continuous per vehicle — that is DC fast charging territory.
Step 2: charger selection
Level 2 chargers (7 to 19 kW) are the workhorse for light-duty depot fleets that have a full overnight window. Cheaper, simpler, and the utility infrastructure is more forgiving.
DC fast chargers (50 to 350 kW) are required for medium and heavy-duty fleets or any application where the charging window is short. Significantly more expensive per unit, and they require dedicated utility infrastructure (often a new transformer).
Smart load management is non-negotiable at fleet scale. The software has to sequence charging so that the depot draws within its utility connection limit at all times.
Step 3: utility coordination
A fleet depot install almost always involves the utility. The questions you have to answer up front: does the existing service entrance have headroom for the new load, or does the service need an upgrade? Does the local distribution circuit have capacity, or does the utility need to upgrade the transformer? What is the demand charge structure on the rate plan you will be on?
Utility lead times for service upgrades vary from a few weeks to more than a year depending on the jurisdiction and the distribution work required. Plan accordingly.
Step 4: physical install
Depot install includes: new service or transformer (if required), distribution panel sized for the load, conduit runs to charger pedestals, charger hardware mounted on pedestals or wall, networking infrastructure for load management, and lighting and bollards around the charging area.
Most fleet installs are phased: install the utility infrastructure first, then the first wave of chargers, then add chargers in subsequent phases as the fleet converts.
Operational considerations
A few things that operators learn after their first depot install:
Always have more chargers than vehicles. Vehicles occasionally need a top-up, vehicles occasionally fail to disconnect cleanly, and drivers occasionally forget to plug in. A 10% buffer is common.
Demand charges can dwarf energy charges if not managed. The smart load management system has to know your demand-charge threshold and avoid it.
Charger reliability matters more than peak power. A charger that pulls 19 kW but fails to start 5% of the time costs more in operational disruption than a 7 kW charger that just works.
Wrapping up
Fleet depot charging is one of the highest-ROI commercial electrical projects for any operator running 10+ vehicles. See our commercial electrical services for the full scope or request a commercial bid.
