A home EV charger should suit the way you actually use your vehicle, not simply be the highest-rated unit available. When considering how to choose EV charger size, the key questions are how far you drive, how long the car is parked, what your existing electrical supply can support, and whether your property may need other electrical upgrades first.
For most homes in Plymouth, a properly specified 7kW charger offers the right balance of charging speed, cost and practicality. However, that is not a rule that should be applied without checking the property and vehicle. A qualified installer should assess the installation properly before recommending a charger size.
What does EV charger size mean?
EV charger size normally refers to its power output, measured in kilowatts (kW). A higher kW rating can supply more energy to a compatible vehicle each hour, which may reduce charging time. It does not automatically mean that every car will charge at that rate.
The charger, your vehicle’s onboard charging equipment and the electricity supply at the property all affect the real charging speed. For example, installing a higher-capacity charger will not make a vehicle charge faster if the car is limited to a lower AC charging rate.
At home, the most common options are 3.6kW and 7kW chargers on a single-phase supply. Faster 11kW and 22kW chargers are generally associated with properties or commercial premises that have a suitable three-phase electrical supply. Three-phase supplies are not standard in most UK homes, and obtaining or upgrading one can involve additional cost and coordination with the distribution network operator.
Start with your daily driving and charging window
The best charger size is usually determined by the hours your car is at home, rather than the maximum speed you might occasionally want. If your vehicle is parked overnight for eight to 12 hours, even a 3.6kW charger can add a useful amount of range. A 7kW charger will normally provide substantially more flexibility for households with longer daily journeys or less predictable routines.
As a broad guide, a 3.6kW charger adds around 10 to 15 miles of range per hour, while a 7kW charger may add roughly 20 to 30 miles per hour. Actual results depend on the vehicle, battery condition, temperature and charging losses.
Consider a household that drives 30 miles most weekdays and plugs in from the evening until morning. A 3.6kW unit may comfortably restore that energy overnight. For someone travelling 80 to 120 miles on a regular working day, a 7kW charger is more likely to provide the convenience they need without relying on public charging.
It is also worth thinking ahead. A charger that is adequate for one electric car may feel restrictive if a second EV is likely in the next few years. That does not always mean installing the largest charger now. It may mean planning cable routes, consumer unit capacity and load management so expansion is straightforward later.
Check what your vehicle can accept
Before choosing a charger, check your EV’s maximum AC charging rate. Many electric vehicles can accept up to 7kW on a single-phase home supply, but some plug-in hybrids and older EVs are limited to around 3.6kW. In that case, fitting a 7kW charger may be sensible for a future vehicle, but it will not make the current car charge at 7kW.
A vehicle may also be capable of 11kW or 22kW AC charging, but that only becomes relevant where the property has an appropriate three-phase supply and the installation is designed for it. Public rapid chargers use DC power and are a separate consideration. A home charger is not intended to replace a rapid-charging stop on a long journey.
Your car handbook, manufacturer app or vehicle specifications should state its maximum AC charging capability. If you are unsure, an installer can help you interpret this alongside the electrical survey.
How to choose EV charger size for your electrical supply
The electrical supply is as important as the charger itself. A 7kW charger can draw around 32 amps for an extended period, which is a significant additional load in a typical home. The installation must be designed around the property’s incoming supply, consumer unit, earthing arrangements and existing electrical demand.
This is particularly relevant in homes with electric showers, immersion heaters, electric heating, induction hobs, hot tubs, workshops or solar battery systems. These items may not all operate at full load at the same time, but they must be considered when assessing the likely demand on the installation.
A professional survey should establish whether there is sufficient capacity, whether the consumer unit has room for the required protective devices, and whether any upgrades are needed. Older fuse boards, damaged cabling or non-compliant earthing arrangements should be addressed before an EV charger is installed.
In many cases, dynamic load management is a practical solution. This monitors the property’s overall electricity use and automatically reduces EV charging output when household demand is high. When demand falls, the charger can increase its output again. It helps protect against overloading the supply while allowing a 7kW unit to be used safely where appropriate.
Load management is not a substitute for a proper assessment. It is one part of a compliant design, selected when it suits the property and the customer’s needs.
Think about charger features, not only kW output
Once the right charging capacity has been identified, the charger’s controls and practical features matter. Smart chargers can schedule charging for off-peak electricity periods, monitor energy use and, in some cases, work with solar generation. For many homeowners, being able to set the car to charge overnight is more valuable than having the highest possible output.
A tethered charger has a cable permanently attached, which can be convenient for daily use. An untethered unit allows you to use your own cable and may look neater when not in use. The better option depends on where the charger will be fitted, how the driveway is used and the vehicle connector you have.
If the property has Solar PV, a charger with solar-aware functionality may allow surplus generation to be directed to the vehicle. This can be useful, but expectations should be realistic. Solar output changes throughout the day and across the seasons, so a solar feature works best as part of a flexible charging approach rather than a guarantee of free charging.
Installation position affects the right choice
The charger needs to be positioned where the vehicle can be connected safely without trailing leads across public paths, shared accessways or areas where cables could be damaged. Cable length, parking habits, wall construction and the route back to the consumer unit all influence the installation cost and design.
For a detached garage, garden office or parking space some distance from the house, the cable run may be a major factor. A longer route can require larger cable, trenching, protective containment or additional distribution equipment. Choosing a lower-rated charger solely to reduce the initial price may be false economy, but equally, paying for extra capacity that the property cannot use is unnecessary.
For landlords and businesses, access control and billing may also affect the choice. A charger used by staff, tenants or visitors may need user authentication, energy reporting or separate metering. Commercial installations often require a wider assessment of demand, parking provision and future expansion.
Safety, certification and compliance
An EV charger is a high-load electrical installation, not simply an outdoor socket with a different connector. It should be installed to current wiring regulations, with appropriate circuit protection, isolation, earthing arrangements and testing. The work must also be notified where required under Building Regulations.
A competent installer will inspect the relevant parts of the existing installation, select suitable equipment and provide certification on completion. They should explain any limitations clearly, including whether a consumer unit upgrade, supply check or load management device is recommended.
Goodwin Electrical approaches EV charger installations as part of the home’s wider electrical system. That means looking beyond the charger itself to ensure the finished work is safe, tidy and appropriate for the property.
Choose for everyday convenience, then install it properly
For many households, a 7kW smart charger is the sensible choice because it restores enough range overnight for normal driving and offers room for changing routines. A 3.6kW charger can still be the right answer where daily mileage is modest, the car has a lower charging limit or the property has supply constraints. Faster options can be worthwhile, but only where the vehicle and electrical infrastructure genuinely support them.
The right charger is the one that fits your vehicle, your property and your routine without placing unnecessary strain on the electrical installation. A site survey from a qualified local electrician gives you a clear recommendation before work begins, helping you charge with confidence every time you arrive home.