EV Fleet Charging Strategy: Managing the Energy Cost of Electrification

Fleet electrification is happening whether UK businesses plan for it or not. The zero-emission vehicle mandate, rising fuel costs, and total cost of ownership arguments are pushing more businesses toward electric fleets each year. The energy cost implications of that transition are significant — and largely unplanned for in most organisations that haven’t yet modelled what charging at scale actually means for their electricity bill.

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The consumption impact

A typical electric van — a Ford E-Transit, Vauxhall Vivaro Electric, or equivalent — consumes 30–40 kWh per 100 miles. A fleet of 20 vans each covering 100 miles per day adds 600–800 kWh of daily electricity demand. Charged overnight across an 8-hour window, that’s 75–100 kW of simultaneous draw — a load that will exceed the existing supply capacity of most SME premises and require a new connection or supply upgrade.

For car fleets, the per-vehicle consumption is lower (typically 15–25 kWh per 100 miles) but the aggregate impact at scale is the same issue. The electrical infrastructure question needs to be addressed before the vehicles arrive, not after.

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Charging strategy: the three variables

When to charge. Overnight charging — between 11pm and 6am — avoids the DUoS red band peak periods (typically 4–7pm weekdays) that attract the highest network charges on pass-through and time-of-use tariffs. For fleets that return to depot overnight and depart in the morning, overnight charging is operationally natural and commercially optimal. Smart charging systems can be programmed to respect time windows and avoid simultaneous vehicle starts that create demand peaks.

How fast to charge. Slower charging is generally cheaper per kWh and places lower peak demand on the supply infrastructure. A 7kW AC charger per vehicle overnight delivers a full charge for most vans within 8 hours. Rapid DC charging (50kW+) is necessary when vehicles need mid-day top-up for longer routes, but adds demand charge exposure and requires higher-capacity supply infrastructure.

How to control the load. Fleet charging management software — integrated with the charge points — coordinates simultaneous charging to stay within a defined site power budget, prioritising vehicles that need the most charge and throttling those that are adequately topped up. This load management capability is the difference between a controlled electricity cost and an unmanaged demand spike that affects your maximum demand reading for the billing period.

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The infrastructure question

Most business premises were not designed for EV charging loads. Before specifying charge point hardware, commission a load assessment against your current supply capacity. If your site is already at or near its agreed supply capacity during operational hours, adding fleet charging without a supply upgrade will cause supply issues — or require demand management that limits your operational flexibility.

DNO connection upgrades for EV charging have lead times that routinely run to 6–18 months for significant capacity increases. This is the single most common cause of fleet electrification delays. Start the DNO conversation early.

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Procurement for EV-heavy sites

A site with significant EV charging load has a different consumption profile from the same site without it — higher overnight consumption, higher total volume, and potentially higher peak demand. This affects contract selection. A tariff with a favourable overnight unit rate, or a pass-through contract where overnight DUoS charges are low, may deliver better total cost than an all-inclusive contract priced on a daytime-heavy profile assumption.

Review your energy contract at the same time as you plan your charging infrastructure — not separately. Telnergy reviews consumption profiles for EV-heavy sites as a standard part of procurement, ensuring the contract structure matches the changed load shape.

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