EV Charger Speed and Tethering Explained: 3.6kW vs 7kW vs 22kW

Home EV chargers come with a range of power ratings — 3.6kW, 7kW, and 22kW are the common figures — and the differences matter more than they might appear. The speed at which you can charge at home is determined partly by the charger hardware, partly by your car's on-board charger, and significantly by the electrical supply your property has. Here is how to make sense of it.

Why most UK homes cap at 7kW

Most UK domestic properties have a single-phase electricity supply, which limits the maximum current available for a charger to around 32A at 230V — roughly 7.4kW. In practice, chargers are rated at 7kW (sometimes 7.2kW or 7.4kW depending on the manufacturer). A 7kW charger on a single-phase supply is the practical maximum for most UK homes without network operator involvement (source).

At 7kW, a car with a 60kWh battery (enough for around 200 miles of range) charges from near-empty to full in roughly 8–9 hours — overnight, essentially (source). For most daily driving patterns in the UK, where average trips are well under 30 miles, you are rarely adding more than 20–25kWh per charge, which takes 3–4 hours at 7kW.

A 3.6kW charger — effectively a 16A supply — is sometimes fitted where the consumer unit or supply cable cannot comfortably support 32A, or where slower charging is acceptable. It is better than a standard 13A socket (which should never be used as a long-term EV charging solution) but noticeably slower than 7kW.

What 22kW requires

22kW home chargers require a three-phase supply — 32A per phase across three phases. Three-phase residential supplies exist in the UK but are uncommon; they are more typical in new-build developments, converted commercial premises, or properties that have had dedicated three-phase supply installed. If you are on a standard single-phase supply, a 22kW charger will simply operate at 7kW — you are paying for hardware you cannot use.

It is worth checking your supply before specifying a charger. Your installer or network operator can confirm whether you have single or three-phase. If three-phase is available — and your car’s on-board AC charger can accept the full rate (many UK EVs cap at 11kW AC, in which case a 22kW unit charges at 11kW) — a 22kW charger can fill a 60kWh battery in around three hours, useful if you are regularly arriving home with a low battery or have a longer commute (source).

Tethered vs untethered

A tethered charger has the cable permanently attached to the unit. An untethered (or socketed) charger has a socket into which you plug whichever cable your car uses — typically a Type 2 connector for most European and UK EVs. The practical difference: tethered is more convenient day-to-day (no hunting for the cable), while untethered is more flexible if you or other household members drive cars with different connector types, or if you expect to change cars. Either works fine; it is mostly a preference call unless you have a specific compatibility requirement.

Smart charging and solar matching

Most modern home chargers include smart features: app control, scheduled charging, and integration with time-of-use tariffs so you can charge automatically when grid electricity is cheapest (typically overnight). Several chargers also integrate with home solar systems — either via a direct API connection to a compatible inverter or via a dedicated solar diverter — to prioritise charging from solar generation during the day rather than drawing from the grid.

For homes with solar panels, solar-matched EV charging is one of the most effective ways to increase self-consumption. Rather than exporting surplus generation at a low SEG rate, that surplus charges the car. If the integration relies on a separate device rather than a built-in charger feature, a solar diverter is the standard solution. Browse EV chargers on SmartSolarHomes to compare smart features and solar compatibility across current models.

Real-world EV charging times at 3.6 kW and 7 kW

Charging time depends on both the charger output and the car's onboard charger (OBC). A 7 kW wall charger only delivers 7 kW if the car accepts 7 kW AC — some older EVs have 3.6 kW OBCs and will charge no faster than that regardless of the charger installed.

For overnight home charging, 7 kW is sufficient for most UK households. An 11 pm–7 am overnight window gives 8 hours at 7 kW = 56 kWh added — enough for a full charge on most EVs from near-empty, and more than enough to top up from typical daily use.

Why 22 kW is rarely useful for UK homes

Three-phase 22 kW AC charging is common in commercial settings and European homes, but most UK residential properties have single-phase electricity supplies with a maximum fuse of 60–100 A. Single-phase limits practical home charging to 7.4 kW (32 A circuit).

Even homes that have a three-phase supply (typically larger detached properties or converted commercial buildings) can technically install an 11 kW or 22 kW charger, but:

• Most UK EVs have 7.4 kW AC onboard chargers — they will not accept 11 kW or 22 kW AC regardless of the charger
• A small number of vehicles (notably some Renault models and the older BMW i3) accept 22 kW AC
• A 7 kW charger fully charges most EVs overnight — paying for a 22 kW unit rarely adds practical benefit

For the vast majority of UK homeowners, a 7 kW single-phase charger is the correct specification.

Smart charging legislation: what UK chargers must do

Since June 2022, the Electric Vehicles (Smart Charge Points) Regulations 2021 have required that all new home charge points sold in the UK include smart charging functionality. Under these regulations, new chargers must:

• Default to off-peak charging and allow grid operators to send signals that delay or interrupt charging during peak demand periods
• Be capable of receiving and responding to dynamic load management signals
• Include a randomised delay feature to prevent simultaneous charging across a street overwhelming the local network
• Be compatible with smart meters (where installed)

This means every new home charger sold since mid-2022 — Zappi, Ohme, Easee, Hypervolt — already meets these requirements. The legislation was introduced to support grid flexibility as EV adoption grows, and it is also what enables features like Octopus Intelligent's automated off-peak scheduling.