What electrifying your depot really costs to run

The headline case for electrifying a depot is running cost: electricity per mile is usually well below diesel per mile. But the size of that saving isn’t fixed — it swings enormously depending on the tariff you’re on and, crucially, when you charge. Two identical depots can have very different energy bills purely because one charges smartly and the other doesn’t.

Your bill is more than a unit rate

Domestic energy is simple: a single price per unit. Commercial energy for a charging-heavy site is not. Your bill has several moving parts, and the unit rate is only one of them. Understanding the others is where the money is.

Time-of-use pricing

The price of electricity changes through the day. Charging overnight, when demand on the grid is low, is typically far cheaper than charging during peak early-evening hours. Because most depots have vehicles sitting idle overnight anyway, this is the single biggest lever an operator has: shift charging into the cheap window and the running cost falls sharply, with no change to operations. This is exactly what smart charging automates.

Demand and capacity charges

Beyond the energy you use, commercial sites are charged for the peak power they draw and the network capacity they reserve. Draw a big spike — say, forty chargers all starting at once — and these charges climb, even if the total energy used is modest. Managing that peak down, by staggering charging and shaving spikes with storage, cuts a cost that many operators don’t even realise they’re paying.

Half-hourly metering

Larger sites are metered every half hour, which sounds like a burden but is actually an opportunity: you get granular data on exactly when and how you use power. That data is the raw material for cutting cost — it shows where your peaks are, which tariff genuinely suits you, and whether storage or on-site generation would pay.

Fixed price or flexible?

You can buy power on a fixed contract for budget certainty, or on more flexible terms that let you benefit from cheap periods (and expose you to expensive ones). For a depot with predictable overnight charging, the flexibility to exploit cheap night-time power is often worth more than the comfort of a flat rate — but it depends on your operation, and it’s a decision worth modelling rather than defaulting.

The bottom line

Don’t judge the economics of electrification on the pump-versus-plug unit price alone. The real running cost is set by when you charge, how sharp your peaks are, and how well your tariff fits your pattern. Get those right and the saving over diesel is substantial; ignore them and you can hand much of it back. Model your actual charging window against a couple of tariff structures before you commit — it’s the cheapest money you’ll ever save.