Does a home charger make sense?

Tom Barnard

28 Oct 2022

So you’ve made the switch to an electric car. The dealer has called to tell you it will be arriving soon and you need to make some preparations; sorting the insurance, signing the finance and cleaning out the sweet wrappers from your old car. 

But if you are new to the electric car world, you are also going to have to think about charging. If you have off-street parking, it will be the most convenient and cost effective to plug in while you are at home. Your car will get ‘filled’ as you sleep.You will need to make a decision though – and probably an investment too.

Can I just use a three-pin plug to charge my car?

The simplest way of charging at home is to use what is nicknamed a ‘granny charger’. This is a cable which plugs into a conventional three-pin socket and has a brick-like block which if filled with gizmos that look after the safety and communications with the car.

They are designed primarily for occasional use though – hence the nickname, which suggests it’s the sort of cable you’d use when you go to visit your granny and need a top up. The power output is limited to around 2kW to prevent overloading the domestic circuits and using them constantly can put a strain on your wiring and fuseboard. If you are intending to charge using a granny, it’s crucial that an electrician checks to make sure your socket is up to the task.

As the granny is only able to charge at around 2kW, it also means you will be taking far, far longer to charge. Going from empty to full in a car like a BMW iX could take more than two full days.

It also means you won’t be able to make the best use of cheaper overnight electricity tariffs, as you’ll not get as many kilowatts in during the limited time the lower rate is active.

It’s also worth remembering that most electric cars will not have a three-pin charger supplied as standard, so you’ll have to buy one from the dealer – and it could cost around £600. Aftermarket alternatives are less, at around £300.

There is a situation where three-pins make sense though, other than when you are visiting your granny. If you have solar panels, they will not usually produce enough to feed your car with the 7.2kW which is supplied by a dedicated home charge unit, so you will end up topping up with expensive daytime electricity from the grid. Using a granny limits the charging to 2kW so you only use your ‘free’ power.

Tom Ford and Juice Booster 2 charge cable Granny chargers are slow, but make sense sometimes

What are the advantages of a dedicated home charger?

The biggest plus point is speed. A wall box will have thicker cables and tap directly into your fuse box, meaning it can supply 7.2kW from a domestic fuse box – more than three times as fast as the granny charger. If you have a commercial property or a three phase supply (rare in domestic houses) then you could get up to 22kW.

Besides being more convenient, it also means you can make the most of the cheaper night rates for electricity. Using Octopus Go as an example, the rate between 00.30 and 04.30 is 7.5p per kWh. The daytime rate set by Ofgem is currently 34p, so a 28kW top up overnight with a home wall box will cost £2.10. With a granny charger on a standard tariff, it will cost £9.52. That means you would pay off the £1,000 cost of a charger installation after 133 top ups or around 15,000 miles in a small electric car.

As most of the newest chargers are also ‘smart’ they will have apps to allow you to monitor usage and start or stop charging remotely. Some also have a setting to limit the amount of energy flow so you can make the most of solar panels and other renewables.

A home wall box will pay itself off in around 15,000 miles if you use a cheaper night time energy rate

What is involved in fitting a home charger?

When you order your charger, the company will come out and survey your house to see what needs to be done. In some cases your fuse box or even main supply will need an upgrade.

The installer will be prepared to run a cable a reasonable distance from the fuse box to the site you want the charger, but don’t expect them to start digging up your drive or running a cable to the end of your garden. A simple installation will take around half a day.

Are all home chargers the same, and how much do they cost? 

No – there are an increasing number of chargers hitting the market all the time. The cheapest can be bought online and you can get a local electrician to fit, but they are unlikely to have smart features. The most expensive – at around £1,300 – can be colour-matched to your car or house.

Several suppliers will allow you to pay for the charger over time using some form of finance. Some car makers and leasing companies will also throw in or discount an installation as part of the deal.

It’s important to think about the future, so if you are planning on getting solar panels you will want the ability to make the most of them with a special charge mode, for example.

You will also need to decide if you want a tethered or untethered cable. The former means the wire is permanently attached to the unit and you unreel it and plug it into the car. Untethered means there is just a socket, into which you plug the car’s own cable.

Untethered is cheaper, neater looking and allows you to charge different types of car, as some older models like the first Nissan Leaf and Mitsubishi Outlander PHEV had Type 1 connectors which are not compatible with more modern cars. However, tethered is certainly more convenient in most situations.

The poshest chargers can be matched to your car or house

Are there still grants available for home chargers? 

If you are a private homeowner, you are out of luck. The chargepoint grant ended in April 2022. However you can still get a grant of up to 75% towards the cost of installing chargepoints if you are renting a property, are a landlord or a business. You can get more information of the government's website here.

Can home chargers do anything else clever?

The next generation of chargers will have V2H and V2G capabilities. This will essentially mean they're two way, so can feed power back into the grid (or your house) if needed. This could be if there is a lot of demand when everyone turns on the oven and TV in the evening, or in an emergency when there is a power cut. As you'll be able to charge when it is cheap - or free if you have solar panels - you can sell or use the energy when it is expensive and make a profit.

You can also register with a charge point sharing app such as Just Park or Co-charger which will offer to rent out your parking space and charge point for a pre-agreed fee to other app users who need to plug in. This seems to work better on a regular use basis than ad-hoc however and both apps are currently a little clunky.

Nissan Leaf, red, 2020, charging on suburban driveway Apps allow you to rent out your charge point to other drivers

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