Mobile megawatt charging: how a 100-truck fleet gets power in days, not years

"Mobile charging" used to mean a van with a battery that rescued one stranded car. Mobile megawatt charging is a different category: trailer-mounted power blocks that put a megawatt or more on a fleet yard in days, run for months or years, and leave when the utility finally delivers. This post explains what it is, how it is sized for a 100-truck fleet, what it costs, and how it exits.

What a megawatt block is

A MegaWatts power block is a standard trailer carrying battery storage, DC power electronics and two to six dispensers. Blocks come in 350 kW, 700 kW and 1 MW+ sizes. They back onto a level pad, connect on a shared DC bus so any dispenser can draw from any block, and charge vehicles on CCS1 and NACS today. The 1 MW+ block is designed to accept a Megawatt Charging System dispenser under IEC TS 63379, published in February 2026 per EV Infrastructure News' MCS guide. Specifications are on the Megawatt Charging page.

Nothing is trenched. No switchgear goes into your building. The block is infrastructure that arrives on a truck.

Why a yard needs it

Because the alternative takes years. First-time depot electrification runs 8 to 18 months per Oxmaint's 2026 planning guide; utility upgrades 3 to 18+ months and major grid work 18 to 36 months per Fleet Rabbit's 2026 guide. Charged Fleet reported in 2026 that grid constraints are now the critical path for fleet electrification. Meanwhile the trucks are delivered, financed and parked.

Sizing a 100-truck yard

Start with energy, not with chargers.

1. Energy per truck per day. A loaded Class 8 uses about 2 kWh per mile; a 175-mile day needs about 350 kWh back.
2. Energy per night. 100 trucks × 350 kWh = 35,000 kWh.
3. Power. Over a 10-hour window at 92% charger efficiency: 35,000 ÷ 10 ÷ 0.92 ≈ 3.8 MW.
4. Blocks. Four 1 MW+ blocks on a shared bus, about 4 MW installed.
5. Dispensers. With a hostler moving cables, a 350 kW dispenser serves roughly six trucks a night, so 18 to 24 dispensers cover the fleet with headroom.
6. Footprint. Four trailer pads at the lane heads plus dispenser lanes, on the order of a quarter acre.

The site power calculator does this with your own numbers; a Site Power Plan measures the site and states a date.

Where the energy comes from

The battery is the point: it converts hours into kilowatts. Three sources fill it.

A small existing service. A 200 kW service delivers 4,800 kWh over 24 hours, enough for about 13 trucks at 350 kWh, with zero generation. Most yards have at least that.

Low-emission generation. An enclosed, tiered generator at the pad edge tops up storage only when the service cannot keep pace. Battery-first design keeps runtime and permits small.

Scheduled energy delivery. For sites with no service and no permit path, charged blocks are swapped or topped up on a schedule.

The on-site power page explains the mix; the Site Power Plan picks it for your site.

What it costs

Three billing structures, all available with a pilot before any term commitment: a flat per-kWh rate with everything included, a flat monthly fee per dispenser with energy passed through at cost, or a metered-hour rental for fleets with their own crews. Rate and minimums are set in your quote; see how pricing works.

The comparison that matters is not against the utility tariff; it is against the cost of idle trucks. Evaisun's 2026 RFP checklist puts downtime at $800 to $1,500 an hour for a 30-van fleet. Scale that to 100 tractors and multiply by the months in the utility timeline above.

How it operates

Mobile does not mean improvised. Blocks run under a 24/7 network operations center with OCPP 2.0.1 telemetry into your fleet system, preventive maintenance and a replacement target for hardware faults. Procurement guidance in 2026 calls for monthly per-charger uptime of 97 to 99% with penalties and treats MTTR as the metric that matters, per Charged Fleet's reliability feature. The MegaWatts SLA is published against that standard.

How it exits

The mobile deployment exists to bridge the utility project, not to replace it. Keep the application moving. When permanent service is energized, blocks relocate; there is no early-termination penalty after the minimum term. Some fleets keep one block as backup for outages and overflow. Most send them to the next yard that is waiting on a substation.

That is the whole idea: megawatts on site, days not years, and no stranded asset when the grid catches up.