How to run a commercial EV charging installation: from site survey to commissioning

In short

Three infrastructure variables set the margin on a commercial EV charging job: the supply already at the site, the measured cable route, and whether the local network has headroom for the added load. Resolve them at survey, carry what cannot be confirmed as labeled provisional sums, and bill the project in four stages tied to milestones written into the order confirmation.

What you will learn

• Supply capacity, measured cable route and grid headroom are the three variables that decide margin on a commercial EV charging project, and all three belong in a written scope confirmation before a price is issued.
• The IET puts the network operator threshold at 13.8 kVA of maximum demand for the whole customer connection: below it you notify within one month of installation, above it you contact the operator before connection.
• The Workplace Charging Scheme pays up to £500 per socket from 1 April 2026, up to 75% of purchase and installation cost, for up to 40 sockets per applicant across all their sites, and runs to 31 March 2027.
• A WCS voucher is valid for 180 days from issue, the customer must apply before any chargepoint is installed, and the installer deducts the grant and recovers it from OZEV afterwards.
• Groundworks, supply upgrades and connection costs fall outside the grant, so grant-eligible and non-eligible lines have to be separated in the quote before the customer signs.
• Commissioning is an eight-step documented sequence ending in the handover pack, and the pack sign-off - not the last day on site - is what triggers the final invoice.

Three things decide whether a commercial EV charging job makes money: the supply capacity already at the site, the cable route from the distribution board to each charger position, and whether the local network has headroom for the added load. None sits on a price list, and all three have to be settled before the quote goes out. The charger units are the part you can price from a catalog; this guide covers everything around them, from survey to handover pack.

Survey the three variables before you price anything

Every commercial EV charging project starts with a site survey, whose purpose is to pin down in writing the assumptions the price rests on.

Supply capacity comes first. Record the rating and location of the incoming supply and main distribution board, and the spare capacity left after a load assessment of what the site already draws. A single-phase supply can be adequate for a site’s current load and nowhere near enough for one 22kW AC charger, which needs three phases. If an upgrade looks likely, it belongs in the quote as a named cost.

Cable route comes second, and it is the one most often estimated rather than measured. Walk every run from the supply point to each charger position and record its length, the containment path, the surfaces it crosses and the ground conditions at each trench location. A straight line across a car park sketch and the route you can actually dig are different lengths, and that difference lands on armored cable, containment, groundworks and crew time at once.

Grid headroom beyond the site boundary comes third. A site can have adequate internal capacity and still need network reinforcement, because the constraint is the local network rather than the building. Ofgem’s guidance on distribution connections is explicit that connection cost varies with the size of the connection, its location, its distance from the existing network and whether the network can accommodate the capacity needed, so it cannot be derived from the charger schedule. Reinforcement is the network operator’s own work, on their programme, and the cost lands on the project.

The survey output is a scope confirmation issued before any price. It records the charger specification and position per bay, the civil scope (trench route, length, depth, surface type and reinstatement standard), the supply assumption, and the exclusions - reinforcement or new connection costs, remedial work to the existing supply, and groundworks beyond the agreed trench route. Where a cost cannot be confirmed until the ground is opened, carry it as a labeled provisional sum rather than a padded rate. A provisional sum is a position the customer has already accepted; a padded rate is a number you have to defend twice.

Decide the network route before you quote the programme

Whether the installation can be connected and notified, or has to be applied for and approved, is a threshold rather than a judgment call. The IET’s guidance for EV charging installations puts it at 13.8 kVA of maximum demand for the whole customer connection: below that the network operator is notified by email within one month of installation, above it the operator has to be contacted before connection.

Calculating the maximum demand of the proposed chargers, applying diversity where a multi-bay site justifies it, and checking that against confirmed spare capacity is the installer’s work at survey stage. Record it in the job file: it is the evidence behind whichever route you quoted. Submit any formal application as soon as the survey confirms one is needed, and carry reinforcement as a labeled provisional sum confirmed on receipt of the connection offer.

Dynamic load management is worth specifying wherever headroom is tight. A controller lets the chargers share available capacity instead of every circuit being sized for full simultaneous output, which can avoid a supply upgrade on a small site altogether. Specify it before hardware is ordered and have the platform vendor confirm compatibility, because changing it after procurement adds cost and delays commissioning.

Sites pairing charging with on-site generation or storage carry a second connection process: solar PV or a battery inverter alongside the chargers brings the generation side into scope, with a G99 application where capacity is above the notify-only limit, an MCS certificate for the generation equipment, and a Smart Export Guarantee tariff for anything exported. Each runs to its own timetable, so confirm at survey which of them apply.

Workplace Charging Scheme administration

The Workplace Charging Scheme is the funding most commercial customers ask about, and the installer carries the administration. It is a voucher scheme run by OZEV and administered by the DVLA, covering up to 75% of the total cost of purchasing and installing the chargepoints, inclusive of VAT. From 1 April 2026 the maximum rate rose from £350 to £500 per socket, applied to installations completed from that date regardless of when the customer applied. An applicant can claim up to 40 sockets across all their sites, and the scheme runs to 31 March 2027.

Three rules set the sequence of the job. The customer must apply for a voucher before any chargepoint is installed, so work done first is not eligible. The voucher is valid for 180 days from issue, and both the installation and the claim have to fall inside that window, because claims against expired vouchers are not paid. And the installer deducts the grant from the customer’s invoice and recovers it from OZEV afterwards, so you carry the grant value as working capital until reimbursement.

What the grant does not cover matters as much on a commercial site. It funds the purchase and installation of the chargepoints; groundworks, supply upgrades, switchboard works and connection costs sit outside it, and on a site needing trenching across a car park those can be the larger half of the project. Separate grant-eligible from non-eligible lines in the quote before the customer signs, and the deduction at final account becomes arithmetic instead of an argument.

Claim evidence is photographic: each chargepoint needs photos clear enough to verify the model and serial number, and to show its location including the parking spaces it serves. Take them at commissioning. Two schemes installers still get asked about, the staff and fleets grant and the commercial landlord chargepoint grant, closed to applications on 31 March 2026.

Procurement, civils and installation

Once the scope and network route are settled, raise purchase orders before anything arrives on site. Issue one PO per equipment supplier - charger units, armored cable and containment, distribution board and protection devices, load management controller - and give the civils sub-contractor their own PO with a written scope covering the trench, reinstatement standard and programme dates. Put the confirmed delivery date on every PO and require written acknowledgment within 24 hours.

Commercial charger units routinely carry multi-week lead times, so order on the day of contract signing. A lead time running concurrently with the network application costs nothing in programme; the same lead time started after the connection is confirmed costs its full duration and stalls commissioning behind it. Check every delivery against its PO before signing the note, and record serial numbers on arrival: they are needed again for the commissioning report, the warranty registration and the claim photographs.

Civils - trenching, ducting and reinstatement - are the first phase on site, and electrical draw-in follows only once containment is complete and any concrete or tarmac has cured. Define the civil scope in the works order before groundworks start: trench route and depth, duct type and size per run, chamber and draw-point positions, cable entry into the board location, and the reinstatement standard. Raise a stage invoice the day the groundworks are signed off.

Electrical installation then runs in sequence: distribution board and sub-main, cable draw-in, charger mounting and final connection, then the load management controller. Track labor against the works order estimate per phase and per crew. If board installation is 25% over estimate on the first day, find out why before the full crew arrives.

Anything beyond the agreed scope - bays added verbally while the trench is open, a route change, civils rework - needs a written variation order with a price and a programme impact, agreed before the work proceeds. Presented as standard practice from the first job it costs nothing in goodwill; raised after the crew has done the work it is a discount request. Raise the second stage invoice at installation complete, when the units are mounted and connected and the board is finished.

Commissioning in eight steps

Commissioning is a documented sequence with a defined order. Work through it in that order, record every result as you go, and hold the final invoice until the pack is signed.

Handover pack and the final invoice

Compile the handover pack before leaving site rather than reconstructing it from email later. It holds a test certificate per charger with serial number, circuit reference and results; the electrical installation certificate; the commissioning report; user guides and platform credentials; the RFID allocation log; warranty registration per unit; as-fitted cable route and board drawings; and the load management settings with the override procedure.

The customer or site manager signs the pack off, and that sign-off triggers the final invoice. Issue it the same day and submit the grant claim in the same week.

The service conversation belongs here too, while the customer is looking at a finished installation. Firmware updates, platform subscriptions and periodic inspection all continue after handover, and proposing a maintenance agreement now beats proposing one after the first fault. Service contracts and fault billing covers how that book is priced and invoiced once it exists.

Stage payments across the project

A commercial EV charging project commonly runs four to twelve weeks from programme start to commissioning, with the installer carrying material and sub-contractor cost throughout. Bill it in stages, and define each stage and its trigger condition in the order confirmation:

• Deposit at order confirmation - covers charger procurement and commits the programme
• Civil and infrastructure complete - raised when groundworks, containment and cable are signed off
• Installation complete - raised when units are mounted and connected and the board is finished
• Commissioning and handover - raised on pack sign-off, alongside the grant claim documentation

A schedule that reads "milestones to be agreed" is not a schedule. Where the stages are not settled up front, the final invoice conversation becomes a debate about what "complete" meant, at the point where you have the least room to settle it.

Multi-site programmes: one job record per site

A rollout across ten or twenty locations is this process repeated, with two additions. Score every site for readiness before anything is scheduled: sites with spare capacity and short runs install immediately, sites needing only a notification go next, and sites needing a formal application enter the queue while the simpler ones are built, so crews stay deployed rather than waiting on the slowest grid approval in the portfolio.

Then distribute the socket allocation before any installation begins, because the 40-socket cap is per applicant across all their sites. Run each site as its own job, with its own cost lines, voucher reference, purchase orders and invoices, so survey time and travel land against the site they were spent on and each final account reconciles without unpicking a programme total.

Where the cost picture has to live

Committed cost against budget, labor against estimate, and the provisional sum against the connection offer that finally arrives only add up to a number if the purchase orders, variations, stage invoices and grant claim hang off one job record.

Zigaflow gives EV charging contractors that record: the quote, purchase orders for hardware and sub-contractors, works orders, stage invoices and commissioning documents in one place, with job margin visible before the final invoice goes out. See how it fits a renewables and EV charging business, or start with the domestic EV charging guide if most of your work is single-charger installations.

Sources

• Changes to electric vehicle chargepoint grant schemes from 1 April 2026Primary sourceGOV.UK (Office for Zero Emission Vehicles) · accessed 2026-09-10
• Workplace Charging Scheme: guidance for applicantsPrimary sourceGOV.UK (Office for Zero Emission Vehicles) · accessed 2026-09-10
• Workplace Charging Scheme: guidance for installers and manufacturersPrimary sourceGOV.UK (Office for Zero Emission Vehicles) · accessed 2026-09-10
• Electric vehicle charging installations FAQs (BS 7671)Primary sourceInstitution of Engineering and Technology · accessed 2026-09-10
• A guide to electricity distribution connections policyPrimary sourceOfgem · accessed 2026-09-10
• The Electric Vehicles (Smart Charge Points) Regulations 2021Primary sourcelegislation.gov.uk · accessed 2026-09-10

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