EV Charging Power Requirements for UK Businesses
A commercial EV charger needs between roughly 3 kW and 350 kW, depending on the type you install. A 7 kW AC unit can often run on your existing supply. An 11 kW or 22 kW charger needs a three-phase supply. Rapid DC units need a dedicated, much larger connection. What your site actually needs depends on how many chargers you fit, how long vehicles stay, and whether you manage the load.
This guide explains the numbers, then shows how to turn them into a sensible design for a workplace, depot or destination site.
TL;DR
Power bands: UK government guidance describes 3–7 kW as slow, 7–22 kW as fast, 50 kW or more as rapid and 100 kW or more as ultra-rapid.
Supply: a 7 kW charger generally does not need new capacity at once. 11 kW needs three-phase 16 A per phase, and 22 kW needs three-phase 32 A per phase.
Don’t multiply: you rarely need nameplate kW times every socket. Load management lets many chargers share one connection.
Dwell time decides: for workplaces and depots, energy needed before departure matters more than peak charging speed.
Grants: the Workplace Charging Scheme requires at least 3 kW per socket, and pays up to £500 per socket from 1 April 2026.
Table of Contents
What the kilowatt figures mean
Charger power is measured in kilowatts (kW). One kW delivered for one hour adds one kilowatt-hour (kWh) to the battery. A 7 kW charger running for an hour adds about 7 kWh, if the vehicle accepts that rate.
UK government connection guidance gives typical planning bands:
Type | Typical power | Indicative time for a standard car battery |
Slow / standard | 3–7 kW | About 3–8 hours |
Fast | 7–22 kW | About 1–3 hours |
Rapid | 50 kW or more | About 20–40 minutes |
Ultra-rapid | 100 kW or more | About 15–30 minutes |
These are planning bands, not promises. The car’s onboard charger and the battery’s own limits can be lower than the chargepoint rating. Many cars cannot use 22 kW on AC at all, so a 22 kW unit may deliver 7 kW or 11 kW to them. Check the vehicles you expect to serve before paying for power they cannot use.
AC or DC: what changes for your site
AC chargers (7 kW, 11 kW, 22 kW) pass mains power to the car, which converts it internally. DC chargers convert power inside the unit and push it straight to the battery, which is why they can go much faster and cost far more to connect.
For most workplaces, hotels, schools and business parks, AC is the right answer. Cars sit for hours, so slower charging covers the need at lower cost. DC makes sense where vehicles must turn around quickly: public charging hubs, high-mileage vans with short dwell times, or sites with strong passing trade.
Supply requirements by charger size
The Energy Saving Trust fleet toolkit sets out example connection scenarios for different charger sizes:
Charger | Supply typically needed |
7 kW AC | Generally no new supply capacity immediately |
11 kW AC | Three-phase, 16 A per phase |
22 kW AC | Three-phase, 32 A per phase |
50 kW DC | Three-phase, 100 A per phase (example scenario) |
Treat this as a planning example. Existing demand, power factor, cable routes, protection, metering and your agreed supply capacity all still need checking on site.
Single-phase or three-phase
A single-phase supply is usual in homes and small premises. Three-phase carries more power and is common in commercial buildings, which is a real advantage for business sites. If your building already has three-phase, 11 kW and 22 kW chargers are often practical. If it is single-phase, you may be limited to 7 kW units unless the supply is upgraded.
Voltage
Current guidance refers to outlets rated at 230 V for single-phase and 400 V for three-phase systems. Your installer will confirm this during the survey, along with earthing arrangements and protection.
Rated power is not delivered power
The number on the charger’s label is not always what a driver receives. UK commercial specifications require the final electrical supply to support the equipment’s full rated capacity. If local constraints prevent that, the equipment must be classified by its actual output.
In practice, delivered power can be reduced by:
the vehicle’s onboard charger
the cable rating
several sessions running at once
load-management settings
the supply available at the board
This matters when you quote charging speeds to staff or tenants, and when you apply for funding.
Don’t multiply nameplate power by socket count
Ten 7 kW sockets add up to 70 kW on paper. Few sites need 70 kW at the same moment. Practitioners size a commercial site from its charging profile, not by multiplying every socket’s rating, as the Energy Saving Trust’s charging profile guidance shows.
A one-socket-per-vehicle layout is operationally simple, but unmanaged simultaneous charging can create demand peaks. With dynamic load management, the system gives more power when fewer vehicles are connected and uses otherwise idle building capacity, for example overnight or when machinery is off.
A worked example
Imagine an office with 20 parking bays and a 100 kVA spare capacity assumption. This is an illustration, not a quote. Twenty 7 kW chargers on paper need 140 kW. Staff arrive between 8 and 9 am and stay about eight hours. Each car needs perhaps 30 to 50 kWh for a typical commute. Over eight hours, a managed 50 kW of shared capacity can deliver 400 kWh, enough for several cars to charge fully. Without management you would need the full 140 kW connection. With it, you might need a fraction of that.
The lesson: ask what energy each driver needs, and by when. Then size the connection to that.
Workplaces: how much power per bay
For staff and visitor parking, 7 kW AC is the common choice and 11 kW gives headroom. It suits employees whose cars stay for a working day.
If you want grant support, note the Workplace Charging Scheme rules: each socket must have at least a 3 kW supply that is not diminished by simultaneous charging. From 1 April 2026, eligible workplaces can receive up to £500 per socket, with applications for up to 40 sockets across sites. The installer guidance confirms the scheme has been extended for a final year until 31 March 2027. The £500 rate applies to installations completed from 1 April 2026.
That 3 kW floor shapes your load management: you can share power, but not below the minimum per socket. For more on funding, see our workplace charging scheme guide for employers and our office EV charging checklist. You can also check your grant eligibility.
Depots and fleets: energy before speed
For a depot, the useful question is how much energy each vehicle must receive before departure, rather than how fast the charger can run. A lower-power overnight strategy can serve more vehicles within an existing connection. A high-power strategy may shorten dwell time but could trigger a network operator assessment or reinforcement.
The IET guide to depot charging of heavy goods vehicles recommends that smart charging prioritise vehicles by urgency, available dwell time and energy required, while coordinating with other site loads. It also warns that suppliers use “smart charging” inconsistently, so your specification should state the scheduling, monitoring, prioritisation, communications and fallback functions you need.
Vehicle condition matters too. As fleets age, electronics faults can change how vehicles behave on charge, which is why it pays to follow electric vehicle repair trends alongside your charging schedule.
For deeper reading on depots, see our guides to depot-first fleet charging, van fleet charging and the operational-first approach to depots.
Destination and public charging
Hotels, leisure sites and business parks sit between the two. Guests stay for hours or overnight, so AC at 7 kW or 11 kW usually serves them well. Public-facing rapid charging is a different project: higher power, larger connections and different compliance routes. If you own land and want to earn from charging, our host an EV charging site and public charging pages explain the options.
Grid capacity and network operators
Higher-power chargers may need a new connection or an upgraded supply. Government guidance states that from 1 April 2023, demand connection customers such as EV chargepoints applying for a connection are no longer charged for distribution network reinforcement to accommodate the connection. Connection charges and timescales still vary, so ask early.
The government infrastructure specification says appropriate power must be available for current chargepoints and future connection locations. It names supply upgrades, load balancing and building electrical-control upgrades as ways to achieve that.
Plan for growth
A frequent hidden cost is designing only for today’s fleet. The Energy Saving Trust notes that planning for growth early can avoid later reinforcement, standing-capacity charges and disruption. Ask for a future-capacity scenario at survey stage, even if phase one uses lower-power AC chargers. Our guides on avoiding grid reinforcement and smart charging for fleets go further.
Smart charging and compliance
Smart charging is more than an app. For workplace chargepoints covered by the 2021 rules, smart functionality includes communications, changing charging rate or timing, demand-side response, continued charging if communications are lost, interoperability and security. Public and rapid chargepoints are excluded from those specific sale regulations, so check the route by charger type and use.
A compliant installation involves more than picking a charger. Government requirements point to BS 7671, BS EN 61851, the IET code of practice, the Electricity Safety, Quality and Continuity Regulations and, for workplaces, the Electricity at Work Regulations 1989. Protection, accessibility and documentation also count. Use a qualified installer for all of this.
A checklist before you commission a survey
Count vehicles and dwell times. Staff, visitors, fleet, or guests?
Check your supply. Single or three-phase, agreed capacity, and current peak demand.
Choose power per bay. 7 kW for long stays, 11 kW or 22 kW where cars need more energy in less time.
Decide on load management. Specify the functions you need, not just the label.
Plan growth. Ask for a future-capacity scenario.
Check grants. Confirm eligibility before ordering.
Agree maintenance. Uptime depends on it.
Our view: size for the profile, not the nameplate
We see the same mistake across sites: buyers add up charger ratings, panic at the total, and either abandon the project or pay for a connection they never use. The better route starts with how people and vehicles actually use the site.
Our approach covers site assessment, design, installation, commissioning and ongoing management. We combine smart charger software with load management, so more chargers can share the capacity you already have. Where it makes sense, we also look at solar PV and battery storage to ease demand. We design for the first phase and leave room for the next, so growth does not mean ripping out what you installed.
The cheapest charger is rarely the cheapest project. The right power level, at the right number of bays, managed well, is.
— Swift Charging
Get your site’s power requirement checked
We design, supply, install and manage commercial charging for workplaces, fleets, hotels, schools and property owners across the UK. We can also help you apply for available OZEV grants, and we offer funded and charging-as-a-service options. Start with a Commercial EV Feasibility Review, or explore our workplace EV charging and fleet EV charging services.
FAQ
Do I need a three-phase supply for workplace EV charging?
Not always. A 7 kW charger generally does not need new supply capacity immediately, while 11 kW and 22 kW chargers need three-phase supply in the Energy Saving Trust’s examples. Many commercial buildings already have three-phase. A site survey confirms what you have.
How much power does each socket need for the Workplace Charging Scheme?
Each socket must have at least a 3 kW supply that is not diminished by simultaneous charging. From 1 April 2026 the grant is up to £500 per socket, subject to scheme rules. Funding is available until 31 March 2027.
Can I install more chargers than my supply can power at full load?
Often yes, with load management. The system shares available capacity between connected vehicles, so the total nameplate rating does not have to be available at once. The design must still meet minimum power per socket and any grant rules.
Is a faster charger always better?
No. If vehicles are parked for hours, a slower charger delivers the energy needed at lower installation cost. Faster units suit short dwell times, but may need a larger connection. The car’s own charging limit also caps the speed it receives.
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