Temporary vs. permanent depot charging: a decision framework

Every fleet depot that electrifies faces the same fork: build permanent charging and wait for the utility, or bring in temporary capacity and start now. The framing is wrong. The permanent project is almost always the right long-term answer, and the real decision is what to do during the months or years it takes. This guide gives six questions that settle that decision, and a rule for when temporary capacity is the wrong tool.

The timelines that force the decision

First-time depot electrification runs 8 to 18 months from plan to energized chargers according to Oxmaint's 2026 fleet charging infrastructure planning guide. The utility service upgrade inside that project runs 3 to 18+ months, and major grid work 18 to 36 months, per Fleet Rabbit's 2026 guide. And Charged Fleet reported in 2026 that grid constraints, not vehicles, are now the critical path for fleet electrification.

If your vehicles arrive before the chargers, and in 2026 they usually do, the gap has to be managed. Doing nothing is a decision to pay for idle vehicles.

Question 1: How certain is the utility date?

Ask the utility for a committed energization date in writing. Three answers are common.

A date within six months, in writing. Bridge minimally or not at all. A small mobile deployment for the first tranche of vehicles may still pay, but the permanent chargers are close.

A date 6 to 18 months out. Bridge fully for the vehicles you have. Structure the contract to exit at energization.

"Pending study" or "depends on upstream work." Bridge fully and plan for the bridge to run two years. Interconnection studies slip.

Question 2: How long is the lease?

Permanent switchgear in a building you lease is capital left behind. If the lease is under five years, or the landlord will not allow trenching, the permanent project may be the wrong project. Mobile blocks sit on the pad and connect at the dispenser; nothing goes into the building.

Question 3: How quickly is the fleet growing?

A permanent installation is sized once. A depot that electrifies 50 vehicles this year and 150 next year either overbuilds now or re-permits later. Mobile capacity scales by adding a block or a dispenser lane in days, so it suits the growth phase. Once the fleet size is stable, permanent capacity sized to the stable number makes sense.

Question 4: Will the depot exist in three years?

Delivery networks re-route. Rideshare and robotaxi hubs move with service areas. Transit and municipal depots are usually permanent. Match the asset to the site's life: permanent for permanent, mobile for mobile.

Question 5: What does downtime cost per hour?

This is the number that decides most cases. Evaisun's 2026 RFP checklist puts downtime at $800 to $1,500 an hour for a 30-van fleet. A 150-van depot is five times that. Multiply by idle hours per day and by the months in the utility timeline, and compare it to the cost of a bridge. The downtime calculator does this with your numbers. When the wait costs more than the bridge, bridge.

Question 6: What is the permit path?

Permanent chargers need electrical permits, utility interconnection and sometimes zoning. Mobile blocks need a temporary electrical permit for the dispensers, and if on-site generation is used, an air permit that depends on state and generator tier. Battery-first blocks minimize generator hours, which keeps that permit simple. Ask any provider to list the permits they file and the ones they do not.

The usual answer for 100+ vehicle depots

Run both. Keep the utility application moving, because it is the cheapest energy you will ever buy. Bridge with mobile capacity for the vehicles you have, under a contract with these features:

• Per-kWh or per-dispenser pricing, quoted per site, with a pilot before any term commitment
• No early-termination penalty when utility service is energized after a minimum term
• Uptime, response and MTTR commitments with credits; 2026 procurement guidance calls for 97 to 99% monthly uptime per charger, per Charged Fleet's reliability feature
• Scaling by block and dispenser under the same agreement
• Relocation, not disposal, at the end

That combination costs more per kWh than the utility for the bridge period and far less than idle vehicles. The pricing page and SLA show how MegaWatts structures it.

When temporary capacity is the wrong tool

A mobile megawatt block is a large piece of equipment. Below roughly 50 vehicles or 500 kW of demand, the economics do not work, and a fleet is better served by Level 2 chargers on the existing service, a small DC charger, or phased vehicle delivery timed to the utility date. MegaWatts sets its minimum at 50 vehicles or 500 kW for this reason and says so on the Site Power Plan form. A provider who will deploy a megawatt block for 20 vans is not doing you a favor.

A one-page decision

A Site Power Plan answers the table for a specific depot in 48 hours, including a bridge size, a price under each model and an exit date tied to your utility's commitment.

Two depots, two answers

A municipal transit depot with a 30-year lease, a stable fleet size and a utility date 10 months out in writing. Permanent is right. A small bridge for the first 40 buses, sized to exit at energization, keeps routes electric during the wait. Long-term, the utility tariff wins.

A parcel delivery depot on a five-year lease, 150 vans growing to 300, and a utility answer of "pending upstream study." Bridge fully. The permanent project may never be the right project at this address; the vans need to run now, and the capacity needs to double next year without a second application.

Most depots are somewhere between, which is why the six questions matter more than any single rule.

What to put in the bridge contract

• Scope: blocks, dispensers, energy source, permits filed by the provider
• Price: per kWh or per dispenser per month, stated in the quote, with any minimum in writing
• Pilot: production operating terms from day one, before any term commitment
• SLA: uptime per dispenser, response, MTTR by fault class, automatic credits
• Scaling: add blocks and lanes under the same terms
• Exit: no penalty after the minimum term when utility service is energized; relocation, not disposal
• Data: OCPP 2.0.1 telemetry and exportable session records
• Insurance and confidentiality: COI before delivery, NDA-by-default