The hidden cost of unmanaged depot charging.
Nobody sends an invoice labelled “bad charging strategy.” The cost is real all the same, it just hides inside the energy bill, the capacity charge, the capex request, and the van that didn’t make its shift.
The default behaviour of an electric depot is simple. Vehicles come back at the end of the day, they plug in, they charge. It works, right up until the first quarterly bill arrives, or the first morning a vehicle isn’t ready, or the day the connection runs out of headroom.
Unmanaged charging is not free. It is just billed in places nobody connects back to the charging strategy. Pull the threads together and the cost is substantial, and almost all of it is avoidable.
The peak you didn’t know you were paying for
Let every vehicle in a 100-strong van depot charge the moment it returns and they all draw power at once. That is a spike of around 700 kW landing on the site at roughly 6pm, the worst possible moment, on the most expensive part of the day.
Two bills follow. The first is capacity: a half-hourly settled site pays an availability charge on the supply capacity it has agreed with its distribution network operator, in kVA, plus excess capacity charges whenever the measured peak breaches it. The second is structural, that 6pm wall is the single number that decides whether the existing grid connection copes or has to be upgraded.
Spread the same charging across the overnight window and the peak falls dramatically, in modelling of a typical depot, from about 700 kW to nearer 250 kW for exactly the same vehicles and the same energy delivered. That takes the site well inside its agreed capacity: it removes the excess charges an unmanaged peak triggers, and it is what makes it possible to renegotiate the capacity the depot contracts for. Reducing agreed capacity is a conversation with the network operator rather than an automatic bill reduction, but the flattened peak is the precondition for having it. Same fleet. Same kilowatt-hours. Different timing.
Same 100 vehicles, same kilowatt-hours, different timing. Illustrative modelling of a 100-vehicle van depot, not measured site data. Actual peaks depend on fleet size, battery capacity, charger ratings, dwell time, and departure schedules.
The wrong hours
Charging on arrival doesn’t just create a peak, it buys electricity at the worst price on the clock.
UK commercial tariffs swing hard through the day. Charge in the early evening and a fleet pays peak unit rates; shift to the small hours and the same energy can cost a fraction as much. Modelling a typical 100-vehicle depot, charging on arrival runs to around £200,000 a year; moving it into cheap overnight windows cuts that by roughly 40%. The network charges stacked on top tell the same story, only sharper:
Modelled against unmanaged charging. Around 40% of the modelled value is charging cost savings available through smart charging today; the remainder depends on demand charge reduction (in development) and flexibility revenue (planned). Indicative ranges only, subject to TOGL modelling. Actual value depends on duty cycle, battery size, tariff structure, site constraints, charging windows, integration availability, and flexibility market access.
One charge deserves a note for what it no longer is: since the Targeted Charging Review took effect in April 2023 the transmission residual is a fixed banded charge, so scheduling cannot reduce it. What timing still moves is the distribution Red band, which can run several times higher than the overnight Green rate with the gap varying enormously by region, and the Capacity Market levy, which is set by a site's demand in the winter early-evening peak. An unmanaged fleet is, in effect, choosing the most expensive electricity on offer and paying the steepest network charges to deliver it.
The upgrade you might not need
The most expensive consequence of a 700 kW spike isn’t on the energy bill at all. It is the connection.
Most depots were never wired for a fleet charging at once. Push demand past what the site can take and the operator faces a grid upgrade: a modest reinforcement at one end of the scale, a new substation at the other, which is a seven-figure capital request and a wait measured in years rather than months. For an electrification plan, that is not a cost line; it is a roadblock.
Most of it is driven by a peak that need not exist. Distribution networks face a straight choice: reinforce the wires, or use flexibility to avoid the bottleneck, and flexibility is consistently the cheaper of the two. Published network trials have deferred reinforcement for a small fraction of what building it would have cost. Flatten the peak and a depot can often live within the connection it already has, deferring or avoiding that bill entirely.
The cost that doesn’t show up as a cost
Then there is the failure nobody budgets for. Across the industry, a meaningful fraction of depot charging sessions do not deliver what was expected: a charger that drops the session, a vehicle-charger handshake that never completes, a unit that reports “online” while delivering nothing. The fault surfaces at 6am, when the vehicle is needed and isn’t charged.
A vehicle off the road is expensive. Research for Mercedes-Benz Vans puts the cost to a UK business at £1,172 per van per day. Unmanaged charging makes that outcome more likely, because nothing is watching the fleet as a whole or recovering from faults before the morning. The cost lands as a missed delivery, a scrambled reshuffle, an overtime shift, never as a line item that says “charging.”
Source: Mercedes-Benz Vans, research by Opinium among 500 UK business decision makers, May 2026.
Why it stays hidden
Add it up and unmanaged charging quietly taxes a depot four ways at once: peak demand charges, expensive-hour energy, premature infrastructure spend, and operational failure. The reason it goes unnoticed is that the cost is distributed. No single invoice names it. It looks like the price of going electric, when in truth it is the price of managing electric badly.
Where TOGL fits
TOGL sits on top of the chargers and CPMS a depot already runs, and is built to turn “charge on arrival” into a coordinated plan: sequencing charging across the night to flatten the peak, shifting load into the cheapest and greenest hours, holding the depot within its existing connection where it can, and watching the fleet as a whole so a failed session is caught and recovered before the shift starts rather than discovered when it’s too late. Depot optimisation is in development, and what it can reach at a given site depends on the site data, vehicle data and charging data available there.
What makes the peak avoidable rather than merely managed is foresight, and that is what the platform is designed around: drawing on telematics so that state of charge and expected arrival are known before a vehicle reaches the gate. Knowing what is coming is what lets a depot flatten the curve before it hits, instead of reacting to a 700 kW wall at six o’clock.
Vehicle tells the depot early
Telematics give state of charge, location and arrival time before the vehicle reaches the gate.
Depot pre-positions charging
Charging is planned against tariffs, site limits and departure times rather than reacting on plug-in.
Network gets a forecast
The local network operator receives an ahead-of-time demand forecast instead of discovering the load.
“The cheapest megawatt is the one you never draw at 6pm. Unmanaged charging pays for that peak again and again.”
Key takeaways
- Unmanaged depot charging creates demand spikes at peak-price hours, a cost most fleets haven't measured.
- Capacity and network charges are a substantial share of a commercial electricity bill, and they are set by brief peaks and the capacity a site contracts for, not by total consumption.
- A grid upgrade is the largest cost of an unmanaged peak, and it can often be deferred or avoided with load management.
- Orchestration using existing chargers and CPMS is designed to strip out most of these costs without new infrastructure.
The point
The cheapest megawatt is the one you never draw at 6pm. Unmanaged charging pays for that peak again and again, in energy, in network charges, in steel in the ground, and in vehicles that aren’t ready. Orchestration is designed to remove most of it, using the chargers, the CPMS and the connection a fleet already has.
The cost was always there. It was just hidden.