Three Phase EV Charging Comparison: 7kW or 22kW?

A three phase EV charging comparison is not simply about choosing the charger with the biggest number on the box. The best option depends on your building’s incoming supply, your vehicle’s onboard charger, how long it is parked, and the other electrical demand on the property. A 22kW unit can be an excellent workplace investment, but it may add little value at a home where the car can only accept 7kW.

For homeowners, landlords and businesses, the right answer starts with a proper electrical assessment. It prevents unnecessary upgrade costs, avoids disappointing charging speeds and ensures the installation is safe, compliant and built for how you actually use your EV.

Single phase and three phase charging explained

Most UK homes have a single phase electricity supply. A typical single phase home charger provides up to 7.4kW, adding roughly 25 to 30 miles of range per hour for many electric cars. For overnight charging, that is more than enough for most drivers.

Three phase supplies deliver electricity over three live conductors rather than one. They are common in commercial premises, larger developments and some newer or high-demand homes. A three phase charger can usually provide 11kW or 22kW, subject to the available supply capacity, charger specification and vehicle capability.

The key point is that a charger only delivers the lowest limit in the chain. A 22kW chargepoint connected to a car with a 7kW onboard AC charger will still charge at around 7kW. It is not a fault with the unit – it is simply how AC charging works.

Three phase EV charging comparison: 7kW, 11kW and 22kW

These range figures are estimates. Efficiency, weather, battery temperature and the car itself all affect the result. Charging also slows as the battery approaches full, particularly where the vehicle is managing battery protection.

7kW charging: usually the sensible home choice

A 7kW charger is the standard choice for a reason. It is fast enough to replenish most daily mileage overnight, works with the single phase supply found in the majority of homes and is compatible with almost every modern plug-in vehicle.

It is also a practical choice where off-peak electricity tariffs are available. If your car is parked from late evening until morning, a 7kW charger can make good use of a cheaper overnight window without placing unnecessary demand on the property.

For a household with one EV, moderate annual mileage and reliable overnight parking, moving to three phase solely for faster charging may not be cost-effective. The supply upgrade can be more expensive than the charger installation itself, particularly where excavation, cable upgrades or network works are required.

11kW charging: a useful middle ground

An 11kW charger needs a three phase supply and a vehicle that can accept 11kW AC charging. Many European EVs support this level, although not all UK-specification cars do. Checking the exact model and year is essential before making a decision.

For homes with an existing three phase supply, 11kW can be a strong option. It offers a meaningful step up from 7kW without the higher electrical demand associated with 22kW charging. It can also suit households with higher mileage, more than one EV, or shorter periods between arriving home and needing to leave again.

At workplaces, 11kW often strikes a sensible balance. Staff vehicles can gain a useful charge during a working day, while the business retains more capacity for lighting, heating, catering equipment, machinery or air conditioning.

22kW charging: fast AC, but not always faster for every car

A 22kW charger supplies up to three times the power of a 7kW unit, but only when the vehicle can receive 22kW AC. In the UK, many EVs are limited to 7kW or 11kW on AC, even when connected to a 22kW charger. Some vehicles offer 22kW AC capability, but it is far from universal.

That does not make 22kW chargepoints a poor choice. They are particularly effective at locations where drivers stay for one to three hours, such as offices, retail sites, restaurants, leisure venues and depots. A faster turnover of charging availability can improve the usefulness of each bay without moving into the far higher costs of DC rapid charging.

A 22kW installation needs careful planning. It can place significant demand on the supply, especially if several units operate at once. Load management is therefore essential on many commercial sites.

Your car’s onboard charger matters more than the chargepoint rating

The chargepoint is only one part of the system. When using AC charging at home or work, the vehicle’s onboard charger converts AC electricity to DC electricity for the battery. Its rating sets the maximum AC power the car can accept.

Before selecting a three phase unit, confirm whether your EV accepts 7kW, 11kW or 22kW AC charging. Do not assume that a larger battery means faster AC charging. Battery size and onboard charger capacity are separate specifications.

This is different from public DC rapid charging. With DC charging, the conversion equipment sits within the chargepoint rather than the car, allowing much higher power levels. A 22kW AC wallbox is not comparable to a 100kW or 150kW DC rapid charger, and it should not be chosen with that expectation.

Can your property support three phase charging?

A qualified installer should assess the incoming supply, existing consumer unit or distribution board, earthing arrangement, cable route and available capacity. At commercial premises, this includes reviewing peak demand and identifying what happens when other major equipment is running.

If your property already has a three phase supply, installing an 11kW or 22kW charger may be straightforward, although the design still needs to account for protective devices, cable sizing and load. If you only have single phase, moving to three phase may require work by the local electricity network operator. Timescales, costs and feasibility vary by area.

For flat blocks, managed developments and workplaces, the wider future plan matters too. Installing one charger without considering the next five or ten can lead to costly alterations later. A scalable distribution design and intelligent load balancing can allow more chargers to operate within the available capacity.

Smart load balancing protects the building supply

Smart charging is particularly valuable for three phase installations. Rather than allowing every charger to draw maximum power at the same time, a load-balancing system monitors demand and adjusts charging output automatically.

For example, a workplace may have several 22kW units installed but only enough spare capacity to run part of that total demand at peak times. The system can share available power between connected vehicles, prioritise selected users or reduce charging temporarily when the building load rises.

This approach can avoid an expensive supply upgrade while keeping charging reliable. It also helps businesses manage energy costs and provides a more practical route for adding chargepoints over time.

Cost, solar and future planning

The cost of a three phase EV charger installation is driven by more than the unit itself. Cable length, groundworks, distribution-board upgrades, electrical testing, parking layout and network operator requirements can all affect the quote. A clear site survey is the right place to identify these costs before work begins.

Solar panels can work well alongside EV charging, but solar output is variable. A smart charger can use surplus generation where available, then draw from the grid when needed. For drivers who are out during daylight hours, scheduled overnight charging on a lower tariff may still provide better value than trying to charge only from solar.

For landlords and business operators, it is worth allowing for future capacity even if only one or two chargers are needed now. Installing suitable containment, spare ways in the board and a charger platform that supports load management can reduce disruption when demand grows.

Choosing the right charging speed

Choose 7kW when your vehicle is parked overnight and you have a standard single phase domestic supply. Choose 11kW when you already have three phase power, your EV supports it and you need a faster turnaround without excessive site demand. Choose 22kW when the property and vehicle support it, and drivers benefit from meaningful charging during shorter stays.

The most effective installation is not necessarily the fastest one. It is the one that matches your vehicle, electrical capacity, parking routine and budget – with the safety, certification and future flexibility to keep working as your needs change. Centralec Electrical can assess the supply, explain the practical options clearly and install a compliant EV charging solution with no hidden costs.