A 22kW EV charger sounds like it should charge three times faster than a 7kW charger.
Sometimes it can.
But home charging speed is not decided by the wallbox alone.
It depends on three separate limits:
Your electrical supply → Your charger → Your vehicle’s onboard AC charger
Whichever of those has the lowest limit determines the real charging speed.
That means a 22kW wallbox connected to a car that can only accept 11kW AC will still charge at around 11kW.
And if the car is limited to around 7kW AC, a 22kW charger may provide little or no charging-speed benefit at all.
The best home EV charger is not the one with the highest kW rating. It is the one that can put the energy you need into the car within the time available.
The Three Limits That Decide Charging Speed
- The Home Supply
- The property has to be able to provide the electrical power required. A typical domestic installation is often single-phase, while 22kW charging normally requires a suitable three-phase supply.
- The Wallbox
- The wallbox has a maximum output. Common domestic ratings include 7kW, 11kW and 22kW.
- The Vehicle
- The car itself has a maximum AC charging rate, controlled by its onboard charger.
The key rule is simple: the lowest limit wins.
For example, a 22kW wallbox plus an 11kW vehicle limit gives approximately 11kW maximum charging.
A higher-rated wallbox cannot force the car to accept more AC power than it was designed for.
A 22kW wallbox cannot make an 11kW car charge at 22kW.
What Does a 7kW EV Charger Mean?
A 7kW home charger is the most common choice for many UK homes.
In practice, domestic chargers are often rated at around 7 or 7.4kW and typically use a single-phase supply.
A 7kW charger can add a substantial amount of energy during an overnight charging period.
For example, over six hours it could theoretically deliver around:
7kW × 6 hours = 42kWh
before charging losses and vehicle limitations are considered.
That is enough energy to replace a significant amount of everyday driving.
7kW is popular because it matches the electrical supply and charging pattern of many homes.
What Does a 22kW EV Charger Mean?
A 22kW home charger is a much larger electrical load.
It normally requires a suitable three-phase supply.
The headline advantage is speed.
If the property can supply 22kW and the car can accept 22kW AC, the charger can potentially add energy much faster than a 7kW unit.
But both conditions have to be true.
If the home is only single-phase, or the car can only accept 7 or 11kW AC, the full 22kW cannot be used.
22kW is not simply a bigger 7kW charger. It usually requires a different electrical-supply arrangement.
Don't Forget 11kW
Although the comparison is usually presented as 7kW vs 22kW, there is an important middle ground: 11kW charging.
An 11kW charger normally uses a three-phase supply but draws less power per phase than a 22kW charger.
It is particularly relevant because many EVs that support three-phase AC charging are limited to around 11kW.
That means a homeowner with three-phase power may gain all of the charging speed the car can use from an 11kW charger.
A 22kW wallbox would then provide no additional charging speed for that vehicle.
For many three-phase homes, the real decision is 7kW vs 11kW — not 7kW vs 22kW.
Check the Car Before Choosing the Charger
Before choosing the wallbox, check the vehicle’s maximum AC charging rate.
This is different from the rapid-charging figure that manufacturers often advertise.
Home AC charging works broadly like this:
Grid AC → Wallbox → Vehicle Onboard Charger → Battery DC
The onboard charger inside the vehicle converts AC electricity into DC electricity for the traction battery.
That onboard charger has its own power limit.
- Car Limited to 7.4kW AC
- 7kW charger gives around 7kW. 11kW charger gives around 7.4kW. 22kW charger gives around 7.4kW.
- Car Limited to 11kW AC
- 7kW charger gives around 7kW. 11kW charger gives around 11kW. 22kW charger gives around 11kW.
- Car Supporting 22kW AC
- A suitable 22kW wallbox and three-phase supply may allow the full charging rate.
The car’s AC charging limit can make a larger wallbox almost irrelevant.
Home AC Charging vs Public DC Rapid Charging
This is an important distinction.
A vehicle may be advertised as supporting 150kW rapid charging, but that does not mean it can accept 150kW from a home charger.
Home charging normally supplies AC electricity. The vehicle’s onboard charger converts that electricity to DC, so its AC charging limit matters.
Rapid public charging normally supplies DC electricity directly to the vehicle’s battery system, bypassing the onboard AC charger.
That is why the same car might support 11kW AC charging at home but 150kW DC charging at a rapid charger.
Your car’s rapid-charging figure tells you very little about which home wallbox power you need.
Home Charging Is Usually a Deadline Problem
When using a public rapid charger, speed matters because you are usually waiting to continue your journey.
Home charging is different.
The car might be connected at 18:00 and not be needed again until 07:00.
That gives 13 hours of parking time.
The useful question is therefore usually not “How quickly can I charge the battery from empty to full?”
It is “Can I replace the energy I need before the car is required again?”
Home charging is usually a deadline problem, not a speed competition.
You Rarely Need to Charge From 0% to 100%
A full-battery charging calculation can make larger chargers look much more necessary than they really are.
Imagine an EV has an 80kWh battery.
That does not mean the home charger needs to put 80kWh into it every night.
If the car used 20kWh during the day, the charging requirement may only be around 20kWh.
| Energy Needed | 7kW | 11kW | 22kW |
|---|---|---|---|
| 10kWh | ~1.4 hrs | ~0.9 hrs | ~0.5 hrs |
| 20kWh | ~2.9 hrs | ~1.8 hrs | ~0.9 hrs |
| 30kWh | ~4.3 hrs | ~2.7 hrs | ~1.4 hrs |
| 40kWh | ~5.7 hrs | ~3.6 hrs | ~1.8 hrs |
| 50kWh | ~7.1 hrs | ~4.5 hrs | ~2.3 hrs |
Real charging will take a little longer because of conversion losses and vehicle behaviour.
But the principle is clear.
If you normally need only 20kWh and the car is parked overnight, 7kW may already complete the job comfortably.
Battery size and nightly charging requirement are not the same thing.
How Much Energy Do You Need Before Morning?
A useful way to estimate required charger power is:
Energy Needed ÷ Charging Time Available
For example, if you need 30kWh and want the charging completed within 6 hours, the required average charging power is 30 ÷ 6 = 5kW.
A 7kW charger already has enough theoretical capability.
If you regularly needed 50kWh inside the same six-hour window, that is 50 ÷ 6 ≈ 8.3kW, so 11kW charging could become more useful, assuming the property and vehicle support it.
This is a much better way to judge charger size than simply looking at the largest kW number.
The Cheap Tariff Window Matters
The car may be parked at home for 12 hours.
But you may only want it charging during the cheapest six.
That changes the decision.
Suppose a tariff provides a cheap period from 23:30 to 05:30. That gives six hours.
A 7kW charger could theoretically deliver 42kWh. An 11kW charger could theoretically deliver 66kWh. A 22kW charger could theoretically deliver 132kWh.
But only if the vehicle can accept those charging rates and the home can supply them.
For many drivers, 42kWh is already far more than they normally need to replace overnight.
The useful charger size is the one that can deliver the energy you need inside the time you are willing to charge.
Does Your Home Have Three-Phase Power?
- Three-Phase Already Available
- 11 or 22kW charging may be relatively straightforward to consider, subject to available supply capacity, vehicle compatibility, other household loads and network requirements.
- Single-Phase Home
- Installing 22kW charging may require a much wider electrical-supply upgrade. That can turn a simple charger installation into a much larger project.
This is one of the biggest differences between 7kW and 22kW charging.
A typical 7kW charger is naturally suited to a single-phase domestic supply. A 22kW charger normally needs three-phase electricity.
A 22kW charger may be a charger decision in one home and an electrical-infrastructure project in another.
Having Three-Phase Does Not Mean You Need 22kW
Three-phase power gives the property more options.
It does not automatically mean the EV should charge at the maximum possible rate.
The home may also have:
- heat pump
- battery storage
- solar inverter
- immersion heater
- electric cooking
- second EV
- other large electrical loads
An 11kW charger may suit the vehicle perfectly.
A 7kW charger may still meet the household’s charging requirements comfortably.
Three-phase gives you options. It does not automatically create a need for 22kW charging.
Is a Three-Phase Upgrade Worth It Just for the EV?
Before upgrading the electrical supply purely to obtain faster EV charging, ask:
- Can the car accept more than 7kW AC?
- How many kWh do you normally need to replace each day?
- How long is the cheap tariff window?
- How often would 7kW fail to finish charging in time?
- Would three-phase benefit anything else in the property?
If a car supports only 11kW AC and normally needs 20kWh overnight, a major upgrade purely to obtain 22kW charging may solve a problem that does not really exist.
But three-phase can make more sense if the property is also moving towards multiple EVs, larger solar and battery systems, higher electrical demand or other three-phase equipment.
Compare the cost of the supply upgrade with the charging problem it actually solves.
Think About the Whole Home, Not Just the Charger
An EV charger can be one of the largest electrical loads in the property.
But it is rarely the only one.
At the same time, the home might be running:
- heat pump
- electric oven
- immersion heater
- battery charging
- washing machine
- dishwasher
- other household loads
A charger therefore needs to be considered as part of the wider electrical system.
The fastest possible EV charge may not be the best use of available capacity at that moment.
Dynamic Load Balancing
Dynamic load balancing allows the charger to respond to what the rest of the home is using.
For example:
Low household demand → EV charging power increases
High household demand → EV charging power reduces
When the household load falls again, EV charging can increase.
This helps prevent the charger and other large loads from exceeding the available electrical capacity.
It also means the number printed on the charger is only its maximum.
A 22kW charger may sometimes charge at 22kW, 15kW, 10kW, 7kW or less, depending on what else is happening.
A charger’s kW rating is its maximum capability, not a promise that it will run at that power continuously.
7kW With Good Load Management vs 22kW Without It
Maximum power is only one charger specification.
Useful functions can include:
- dynamic load balancing
- smart tariff integration
- solar surplus charging
- scheduled charging
- departure-time scheduling
- HEMS integration
- multiple-EV load sharing
A well-integrated 7kW charger may provide a better overall charging experience than a poorly coordinated 22kW charger.
Charging power and charging intelligence are separate specifications.
What About Solar EV Charging?
A larger wallbox does not create more solar generation.
Suppose the house has 3kW of spare solar generation.
A 22kW charger cannot magically charge the car at 22kW from that surplus.
Only around 3kW is available from solar at that moment.
The important solar-charging factors include:
- actual solar surplus
- charger minimum current
- charger modulation
- household load
- battery storage priorities
For solar charging, available surplus usually matters more than maximum wallbox power.
What About Home Battery Storage?
Battery storage adds another large controllable load.
During a cheap tariff period the home might try to do all of these at once: EV charging, plus home battery charging, plus heat pump operating, plus normal household demand.
That can create a substantial electrical load.
The system may therefore need to decide which load gets priority.
For example:
- charge the EV first
- charge the battery first
- split available power
- delay one load
- respond to tariff or departure time
This is where whole-home energy management becomes particularly useful.
The fastest EV charging strategy is not always the best whole-home energy strategy.
What If You Have Two EVs?
Two EVs do not automatically mean the home needs two maximum-power chargers.
The useful question is:
How much energy do both vehicles need before their next journeys?
Possible approaches include:
- two 7kW chargers
- shared available capacity
- staggered charging
- departure-time priorities
- three-phase load distribution
- dynamic load management
For example, one vehicle may need to leave at 06:00 while the other is not needed until 09:00.
An intelligent system could prioritise the first car, then redirect charging capacity to the second.
Two cars do not automatically require twice the charging power. They require enough shared energy before each car needs to leave.
Single-Phase vs Three-Phase Load Distribution
There is another advantage to three-phase charging beyond headline speed.
A typical 7kW single-phase charger places a significant load on one phase.
An 11 or 22kW three-phase charger can spread EV demand across three phases.
In a highly electrified property, that can be useful when balancing:
- EV charging
- heat pump demand
- battery inverters
- solar
- other electrical loads
The exact electrical design needs to be assessed for the individual property.
What About Plug-In Hybrids?
Plug-in hybrids often have smaller traction batteries and lower maximum AC charging rates.
That means a 22kW charger may provide very little benefit.
If the vehicle can only accept around 3.6 or 7kW AC, that limit will apply regardless of the wallbox rating.
Check the vehicle’s AC charging limit before over-specifying the charger.
Future-Proofing Done Properly
- Future-Proofing the Wallbox
- Installing a charger capable of a higher future output. That may be useful where three-phase is already available, a future vehicle may support higher AC charging, or the charger can be configured at a lower rate initially.
- Future-Proofing the Electrical Installation
- Often more important. Consider cable size, cable route, containment, consumer-unit capacity, communications, CT monitoring, possible future three-phase arrangement and space for additional chargers.
It is common to hear “Install 22kW now so it is future-proof.”
But there are two different types of future-proofing.
The charger itself is relatively easy to replace compared with buried cable, distribution equipment or major supply infrastructure.
Future-proof the difficult-to-change infrastructure first. The wallbox is one of the easier parts to replace.
When Is 7kW Usually Enough?
A 7kW charger is often a strong fit where:
- the property has a normal single-phase supply
- daily mileage is moderate
- the car is parked overnight
- the vehicle supports around 7–11kW AC
- the cheap tariff window is long enough
- the required daily energy can be replaced comfortably
For many households, 7kW already solves the actual charging requirement.
The fact that a faster charger exists does not mean the home needs it.
When Does 11kW Start to Make Sense?
11kW charging becomes worth exploring where:
- three-phase power already exists
- the vehicle supports 11kW AC
- daily mileage is relatively high
- the tariff window is shorter
- the household has several large electrical loads
- faster overnight energy replacement would genuinely help
For many modern EVs, 11kW is the practical upper limit for home AC charging.
When Can 22kW Make Sense?
22kW charging can be worthwhile where:
- three-phase power is already available
- the vehicle genuinely supports 22kW AC
- high amounts of energy regularly need replacing
- charging windows are short
- multiple EVs are involved
- the wider home electrical system benefits from three-phase
- the installation has sufficient available capacity
It can also make sense as part of a wider property electrification strategy.
But it should not be specified simply because it is the largest available wallbox rating.
22kW makes sense when the home and the car can both use it — not simply because the charger supports it.
Which Charger Size Looks Most Like Your Situation?
| Situation | Worth Exploring |
|---|---|
| Typical single-phase home | 7kW |
| Vehicle limited to around 7kW AC | 7kW |
| Three-phase home + 11kW vehicle | 11kW |
| Three-phase home + 22kW-capable vehicle | 22kW may make sense |
| Short cheap tariff window + high daily mileage | 11 or 22kW worth comparing |
| Normal overnight parking | 7kW often sufficient |
| Two EVs | Smart load sharing |
| Solar-focused charging | Smart modulation may matter more than maximum kW |
| Major future electrification | Consider the whole-home three-phase strategy |
The correct choice still depends on the property, vehicle, tariff and future plans.
What Should You Ask Before Choosing?
Before deciding between 7, 11 or 22kW charging, ask:
- What is the vehicle’s maximum AC charging rate?
- Is the property single-phase or three-phase?
- How many kWh normally need to be replaced?
- How long is the cheap tariff window?
- Will 7kW already finish charging in time?
- Is 11kW actually the vehicle’s maximum?
- What other large electrical loads are in the property?
- Does the charger support dynamic load balancing?
- Will solar be added?
- Will battery storage be added?
- Is a second EV likely?
- Is the electrical infrastructure being future-proofed?
The answers to those questions are far more useful than asking only “Which charger is fastest?”
EV Charging Time & Cost Calculator
Use the Energy Flow Hub EV Charging Time & Cost Calculator to estimate how long your own EV charging session could take.
Enter:
- EV battery size
- current state of charge
- target state of charge
- charger power
- start time
- electricity tariff
The calculator can estimate:
- energy required
- grid energy required
- approximate charging time
- expected finish time
- cheap and standard tariff split
- estimated charging cost
This makes it much easier to compare whether 7, 11 or 22kW would actually change the outcome for your normal charging pattern.
The Practical Answer
For many UK homes and vehicles, 7 kW charging is enough to replace normal daily driving during an overnight parking period.
An 11 kW or 22 kW charger becomes useful only when the property supply, the vehicle’s onboard charger and the charging schedule can all use the additional power.
Choose the charging rate that completes the real charging job reliably. Faster on the wallbox label is not automatically faster at the car or more valuable to the household.