Finding
Heavy-duty depots move up a three-step ladder, and the move from step one to step two is forced by the utility, not chosen by the fleet
A plug-in charging site needs a grid connection sized for its full peak: 20 trucks on 1.2 MW Megachargers is 24 MW. US transformer deliveries averaged about 128 weeks in 2025, so most truck depots open with a battery that covers the gap between the feed they can get and the peak they need.
The second step, a battery-backed depot, cuts the bill: it trims the 15-minute peak that sets demand charges (see Depot Charging Costs). The third step, a fleet energy depot, adds grid-forming inverters, an on-site microgrid controller and scheduling tied to the fleet's dispatch, so the site keeps working through an outage and charges each truck when its route requires rather than when it arrives. Greenlane's truck stops in Colton, California and on I-45 in Dallas and Houston, WattEV's solar-and-storage depots and Tesla's Semi sites sit between steps two and three.
China took a different path for heavy trucks. Battery-swap stations run by CATL's Qiji Energy and others charge packs on racks at a steady rate and swap them in about five minutes, which turns the truck peak into a flat station load. Driverless fleets push all depots toward step three: Tesla's Austin robotaxi lots and its Megachargers at Giga Texas run on schedules no driver sets. See Fleet Energy Depots for the depot definition and Megawatt Charging System for truck chargers.
Three steps
Charging site, battery-backed depot, fleet energy depot
| Capability | Charging site | Battery-backed depot | Fleet energy depot |
|---|---|---|---|
| Main job | Charge vehicles | Cut the electricity bill | Run the fleet's energy and operations |
| Fast charging | Yes, first come first served | Yes | Yes, scheduled by duty cycle |
| Battery storage | No | Grid-following, peak shaving | Grid-forming, can black start |
| Grid outage | Offline | Minutes to an hour on critical loads | Degraded but operating |
| Grid feed needed | Full peak load | Average load plus margin | Average load; can open before the upgrade |
| Local control | Charger network cloud | Energy management system | On-site controller that runs without the cloud |
| Fit for driverless fleets | No | Partial | Yes |
Depot types
Heavy-duty and high-utilization depots in operation
Power envelopes are ElectronsX estimates for a full build-out.
| Depot type | Site power | Design elements | Examples |
|---|---|---|---|
| Class 8 regional and drayage | 5-20+ MW | MCS or 350-400 kW DC, pull-through lanes, battery buffer | Greenlane Colton (CA), Dallas and Houston (TX); WattEV Long Beach and Bakersfield; TeraWatt Rancho Dominguez; Tesla Semi depots at PepsiCo Sacramento and Modesto |
| Heavy-truck battery swap | 2-10 MW per station | Stationary charging racks, robotic swap bay, standardized packs | CATL Qiji and other swap networks on Chinese coal, steel and port routes |
| Transit buses | 2-10 MW | Plug-in DC, overhead pantographs, on-route chargers | Shenzhen's all-electric BYD fleet; LA Metro, King County Metro, European city depots |
| Robotaxi hubs | 1-14 MW | Dense DC stalls, wireless pads, cleaning and calibration bays | Tesla St. Elmo Road and Ridgepoint Drive (Austin); Waymo depots in Phoenix, San Francisco, Los Angeles, Dallas; Baidu Apollo Go in Wuhan |
| Last-mile vans | 1-5 MW | Level 2 plus some DC, battery peak shaving | Amazon Rivian EDV stations; UPS, FedEx and DHL depots; JD Logistics in China |
Sources
Sources and scope
- Scope
- Heavy-Duty Fleet Charging Depots
- Sources
- Wood Mackenzie transformer lead times (2025); Greenlane; WattEV; Tesla; CATL; operator disclosures
- Updated
- October 2026