Three Unknowns That Turn a Commercial EV Charging Quote Into a Loss

The hardware cost of a commercial EV charging installation is the one number installers can price with confidence. The charger unit, the back-office software, the mounting post - these sit in a catalog with a price next to them. What does not sit in a catalog is the electrical infrastructure beneath the job: the existing site supply, the cable run from the distribution board to where the chargers need to go, and whether the local grid can take the additional load at all. Those three variables are where commercial EV charging quotes go wrong. Installers who price the hardware and assume the infrastructure is fine get a surprise after acceptance. Installers who resolve the unknowns before the quote goes out price the job correctly and protect their margin.

The Hardware Is the Predictable Part

A 7kW to 22kW AC workplace charger typically costs several thousand pounds installed in the UK in 2026, according to data from Swift Charging's commercial cost guide. A 50kW DC rapid charger runs to tens of thousands of pounds. These figures are consistent and available from any supplier. The hardware cost tells an installer what the job will cost if the site is straightforward. Most commercial sites are not straightforward.

Infrastructure costs are not predictable from a product specification. They depend on what is already at the site, what needs to be added, and what the grid operator needs to do before power can be delivered. On a complex project, infrastructure costs can exceed hardware costs entirely. According to the same Swift Charging data, infrastructure and grid reinforcement - not the charger - are the single biggest reason a £4,000 estimate becomes a £15,000 invoice.

Three Variables That Decide Whether the Job Makes Money

The first variable is existing supply capacity. A site might have a single-phase supply adequate for its current electrical load but nowhere near enough for even one 22kW AC fast charger, which requires three-phase power. The cost of upgrading from single-phase to three-phase supply in the UK ranges from £5,000 to £12,000, including grid operator charges and internal consumer unit changes, according to figures from Utility Solutions Provider's 2026 installation cost guide. That cost sits entirely outside the charger price - and if it is not identified at survey stage, it arrives as a variation after the job is accepted.

The second variable is cable run distance. A charger installed close to an existing distribution board with a clear route adds a relatively modest sum to the project. The same charger across a large car park, through tarmac or landscaped areas, is a different project. Trenching through tarmac or concrete adds meaningful cost per metre. On older commercial buildings with routed cable runs and no convenient ducting, the cable route alone can add more to the total job cost than the charger hardware. An installer who surveys the proposed charger location but not the cable route has not completed the site assessment.

The third variable is grid capacity beyond the site boundary. A site can have adequate internal supply capacity and still face a grid reinforcement requirement if the local network cannot absorb the additional load. This is more common on multi-bay projects, on DC rapid charging installations, and on sites in areas where the distribution infrastructure is already carrying significant load. When reinforcement is required, the grid operator handles the physical work, but the timeline extends - and the cost is passed to the project. According to Govier Electrical Engineering's commercial installation timeline guide, a small workplace AC installation with spare grid capacity can complete in four to eight weeks. A multi-bay DC rapid charging site requiring a new electrical supply can take six to twelve months or longer. A project sold as a six-week job that takes six months has cost the installer in ways that never appear on the original quote.

Why the Assessment Has to Come Before the Quote

The pattern in most overrun cases is the same. The customer wants a number quickly. The installer prices the hardware and gives a budget figure. The customer accepts. The survey then reveals infrastructure requirements that were not in the budget. The installer has three options: absorb the cost, raise a variation the customer did not expect, or try to find a compromise that satisfies neither side.

The customer accepting a budget figure is not an agreement to fund whatever the survey finds. If the survey happens after acceptance, the variation conversation is harder - the customer has already bought the job at one price and sees additional cost as an error, not a discovery.

Installers who run a meaningful electrical assessment before quoting avoid this problem. The assessment does not need to be a full survey on every job - a preliminary capacity check with the site's existing electrical distribution data is often enough to identify whether a grid application or supply upgrade is likely. That check takes time, but less time than a disputed variation order.

What to Establish Before the Quote Goes Out

Four questions resolve most of the infrastructure uncertainty before a quote is written:

What is the existing electrical supply - single-phase or three-phase, and what is the available capacity in amperes? This determines whether a supply upgrade is likely before a charger is specified.

How far is the proposed charger location from the distribution board, and what is the cable route? An internal route through a finished building, a run across a car park, or a route requiring road crossing have very different cost profiles.

How many chargers and at what power output - and does the combined load require a grid operator assessment? Single AC chargers on sites with adequate supply typically need only a notification. DC rapid chargers or multi-bay installations on constrained sites may need a formal connection application.

What is the programme? If a grid operator assessment reveals reinforcement is required, the project timeline changes. A customer who needs chargers operational in six weeks may not be compatible with a twelve-week reinforcement timeline. That is better established before the quote is accepted than after it.

A quote that answers all four questions is not just more accurate - it is more defensible. When the customer later asks why the project cost what it did, the answer is already in the documentation. For installers managing multiple commercial projects simultaneously, tracking which jobs have completed their infrastructure assessments and which have not is the difference between a pipeline that holds its margin and one that quietly leaks it.

The business challenge for commercial EV charging installers is not finding work. Demand is growing and projects are there. The challenge is pricing the work correctly when the visible cost and the total cost are two different numbers. Infrastructure and grid connection are the gap between them, and closing that gap starts with the survey, not the invoice.

Sources

• Commercial EV charger installation cost: your 2026 UK guideSwift Charging · accessed 2026-09-10
• EV Charger Installation Cost UK 2026: Commercial vs DomesticUtility Solutions Provider · accessed 2026-09-10
• How Long Does a Commercial EV Charger Installation Actually Take?Govier Electrical Engineering · accessed 2026-09-10

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