7kW vs 22kW EV Charger: Which Do You Actually Need at Home?

One question that comes up repeatedly on Faithful Spark surveys is whether the homeowner should be asking for a 22 kW charger rather than the standard 7 kW unit. The curiosity is understandable: if 7 kW is good, surely 22 kW is three times better? In practice, for the overwhelming majority of Scottish homes, the answer is no. This guide explains exactly what separates a 7 kW and a 22 kW EV charger, which Scottish households can actually use a 22 kW unit, why 7 kW is the right answer for almost every Aberdeen and Aberdeenshire driveway install, and the limited but real scenarios where 22 kW makes commercial sense.

The fundamental difference: single phase vs three phase

The difference between a 7 kW and a 22 kW charger is not primarily about the unit on your wall. It is about the electrical supply entering your property.

Almost every domestic property in Scotland is served by a single phase supply. Single phase is the standard residential connection: one live conductor at 230V, delivering a maximum continuous current of 100A across the whole property. A 7 kW EV charger draws 32A on this single phase supply. That is the maximum practical load you can run continuously from a single phase supply without competing with the rest of the household’s electrical demand.

A 22 kW EV charger requires a three phase supply: three separate live conductors at 230V each (or 400V line to line), delivering 32A per phase simultaneously. Three phase supplies are standard for commercial and industrial premises, uncommon in residential properties except in specific circumstances. The 22 kW figure comes from 3 phases multiplied by 32A multiplied by 230V, which equals approximately 22 kW.

If you have a single phase supply (which you almost certainly do if you live in a domestic property in Aberdeen or Aberdeenshire), you cannot run a 22 kW charger regardless of what unit is mounted on the wall. The supply physically cannot deliver that power. A 22 kW unit connected to a single phase supply will operate at 7 kW at best, or more likely at a reduced capacity depending on how the unit handles the phase mismatch. You would be paying significantly more for a charger that performs identically to the 7 kW unit you could have bought instead.

Which Scottish properties have three phase supplies?

Three phase domestic supplies are found in the following property types:

• Converted farm steadings and agricultural properties in rural Aberdeenshire. Agricultural properties routinely have three phase supplies for barn equipment and outbuildings. When these are converted to residential use, the three phase supply often remains.
• Large detached rural properties where the incoming supply was originally specified for electric heating or workshop use.
• Some new build plots where the buyer specifically requested three phase at the planning or pre construction stage.
• Properties that previously housed small businesses on the ground floor, where a three phase supply was installed for the commercial use and retained when the property reverted to residential.
• Self build properties where the owner requested three phase supply from SP Energy Networks at the connection stage.

If you are unsure whether your property has a single phase or three phase supply, the simplest check is to open your consumer unit. A single phase consumer unit has one incoming live bus bar and breakers arranged in a single row. A three phase consumer unit has three incoming bus bars (usually labelled L1, L2, L3) and breakers arranged in three columns. If you see three columns of breakers, you have three phase. You can also check your electricity meter: three phase meters typically have more terminals visible and are physically larger.

The EV side of the equation: what your car can actually accept

Even if your property has a three phase supply, the power your EV can accept for AC home charging is limited by the car’s onboard charger, not by the wall unit or the supply.

This is where many homeowners get surprised. The socket on your EV car is a Type 2 inlet (IEC 62196), and it accepts AC current. But the car’s onboard charger converts that AC to the DC that charges the battery. The conversion hardware inside the car has a power rating ceiling, and most UK EVs have an onboard charger rated at 7.4 kW. That means even if you plug a 22 kW wall charger into a 22 kW capable property, the car will charge at 7.4 kW because the onboard charger cannot accept more.

A smaller number of EV models have 11 kW onboard chargers, which accept three phase AC at 16A per phase. These include the BMW i3 (some variants), older versions of the Renault Zoe, and some Porsche and Audi models with optional upgraded onboard chargers. Very few EVs have 22 kW onboard chargers: the original Renault Zoe R240 is the most cited example, and it is now an older model with declining market share.

The practical implication for a Scottish homeowner buying a new EV in 2026 is this: check the onboard charger rating of your specific vehicle before specifying a charger above 7 kW. For the Volkswagen ID.4, the Kia EV6, the Tesla Model 3, the Hyundai Ioniq 5, the Polestar 2, and the vast majority of current market bestsellers, the onboard charger maxes out at 11 kW at three phase or 7.4 kW at single phase. A 22 kW charger provides no benefit over a 7 kW charger for these vehicles.

The overnight charging reality check

The strongest argument against spending money on anything above 7 kW for a domestic install is the overnight charging maths. Consider a typical 70 kWh EV battery (Volkswagen ID.4 size) that arrives home at 20 percent charge:

• Remaining capacity to fill to 80 percent: 42 kWh
• At 7 kW, charging time: approximately 6 hours
• At 11 kW, charging time: approximately 3.8 hours
• At 22 kW, charging time: approximately 1.9 hours

On overnight charging (plugging in at 22:00 and leaving at 07:00), all three speeds fill the same battery to the same level. The 9 hour window is more than enough for any of them. The faster charge speed only matters if you need to charge in less time than the overnight window allows, which applies to scenarios like: arriving home at 23:30 and needing a full charge by 06:00 (still fine at 7 kW), or using the car twice in the same day for long trips. For the standard Aberdeen commute and family use case, 7 kW overnight is never the limiting factor.

When does 22 kW make genuine sense?

There are real use cases where a 22 kW capable charger is the right specification:

• Commercial car parks and hospitality: where multiple vehicles may need to charge during the day and full charges need to be delivered within 2 to 3 hour dwell times rather than overnight. A hotel guest arriving for a 3 hour lunch meeting benefits from 22 kW in a way a homeowner does not.
• Fleet charging depots: where commercial vans (Renault Kangoo E Tech, Vauxhall Vivaro Electric, Ford E Transit Custom) have 11 kW onboard chargers and a mid shift turnaround means overnight charging is not available.
• Agricultural properties with three phase: where the supply is available anyway and the owner wants to charge a fleet vehicle or agricultural EV at maximum speed during a working day.
• High mileage households: where a driver regularly covers 200 to 300 miles per day and a late evening return means overnight charging is not quite enough. At 7 kW, a 100 kWh battery charges from 10 percent to 80 percent in approximately 10 hours. If arrival time is midnight and departure is 06:00, 7 kW only delivers 42 kWh, not a full charge. At 22 kW, the same 10 percent to 80 percent charge completes in 3.2 hours and well within the available window.

What about 11 kW? The middle option

Between 7 kW and 22 kW sits the 11 kW option: three phase at 16A per phase. This is the relevant specification for properties with three phase supplies and EVs with 11 kW onboard chargers. The Zappi, Ohme, and Easee all offer three phase variants capable of 22 kW, but can be configured (or limited by the car) to operate at 11 kW. For a homeowner on a three phase supply with a BMW or Porsche with an 11 kW onboard charger, specifying an 11 kW capable charger is the correct move. For most other households, it is an unnecessary complication and cost premium.

Cost comparison: 7 kW vs three phase installs

The installation cost difference between a 7 kW single phase install and a three phase capable install is meaningful:

• A standard 7 kW single phase domestic install in Aberdeenshire costs £900 to £1,500 all in, including the charger unit and the OZEV grant deducted from the invoice.
• A three phase install requires a three phase capable charger unit (typically £150 to £300 + VAT more expensive than the single phase equivalent), three phase cable and protection, and a three phase consumer unit connection if not already in place. Total cost: £1,400 to £2,200 + VAT depending on the cable run length and consumer unit specification.

Given that most households with three phase supplies still have EVs whose onboard chargers max out at 7.4 kW, the additional investment in three phase infrastructure would deliver no benefit in charging speed. The money is better spent on a quality 7 kW single phase unit and, if the household has solar panels, a Zappi to make use of the solar generation.

For the full cost breakdown including grant options, see our guide on EV charger installation costs in Scotland.

Frequently asked questions

My neighbour has a 22 kW charger. Should I get one too?

Not unless you have a three phase supply and a vehicle with at least an 11 kW onboard charger. If your neighbour has a 22 kW charger on a single phase supply, it is almost certainly running at 7 kW. The spec on the box does not translate to the actual charge rate if the supply and the car cannot support it.

Can I upgrade from 7 kW to 22 kW later?

You can upgrade the charger unit at any time. But if your property is single phase and your car’s onboard charger is limited to 7.4 kW, upgrading the wall unit will not change the actual charge speed. A supply upgrade to three phase (if your property does not already have it) requires an application to SP Energy Networks and can cost £1,500 to £5,000 + VAT depending on distance from the distribution network. This is a major project and is rarely justified for domestic EV charging alone.

How do I find out if my EV can accept more than 7.4 kW?

Check the vehicle’s technical specification sheet for “AC charging maximum” or “onboard charger capacity”. This is usually listed in the official specification published by the manufacturer. For most current UK market EVs, this figure is 7.2 kW or 7.4 kW. If it is 11 kW or higher, your car can benefit from a three phase supply. If it is 7.4 kW or lower, 7 kW is the optimum home charger specification.

Does a faster charger reduce my electricity cost?

No. The cost per kWh is set by your electricity tariff, not by the charge speed. Charging 50 kWh at 7 kW costs the same as charging 50 kWh at 22 kW at the same tariff rate. The only financial argument for faster charging is if it allows you to shift more charging into a cheaper off peak window within a limited overnight period.

What does Faithful Spark recommend for most Aberdeen households?

A 7 kW OZEV approved smart charger (Zappi, Ohme, or Easee depending on your household setup) on a dedicated 32A circuit from the existing consumer unit. This covers every car currently on the UK market, works on the single phase supply that virtually every Aberdeen house has, qualifies for all applicable grants, and delivers overnight charges that more than cover average daily driving. We confirm the right specification at the free survey.

Book your free EV charger survey

Not sure which spec is right for your property and your car? A Faithful Spark survey takes 30 minutes, costs nothing, and results in a clear written recommendation and a fixed price quote. We cover Aberdeen, Peterhead, Ellon, Fraserburgh, and the wider Aberdeenshire area.

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Faithful Spark Electricians. NICEIC approved. OZEV listed. Local Aberdeen team. Serving Aberdeen, Peterhead, Ellon, Fraserburgh and across Aberdeenshire.