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Charging your electric car at home

Neil Briscoe

Words: Neil Briscoe - @neilmbriscoe

Published on: July 1, 2021

Words: Neil Briscoe - @neilmbriscoe

Published on: July 1, 2021

Lots of EV charger options on the market, but the critical part is your electricity supply.

If you've decided to go electric for your next car, then being able to charge at home is pretty crucial. With the public charging network still pretty sparse, charging up at home, preferably overnight, is going to take care of the majority of your motoring needs, meaning that you'll only have to access the public network when out and about on longer journeys.

With the current average driving distance of less than 30km per day, most new electric cars can easily get you from the beginning to the end of the week without needing a full charge-up, although, as with mobile phones, it's a good idea to keep things topped up just in case you have a longer journey at short notice.

Home chargers for electric cars

Mostly, home charging points will provide either 3.7kW or 7.4kW of charging capacity, and this is enough to charge most current EVs - except for those with the largest batteries - overnight. There are options for higher power outputs - 11kW or even 22kW - but that will depend hugely on the mains electricity connection to your house, and how much power demand your house is capable of dealing with.

According to the Sustainable Energy Authority of Ireland (SEAI), an average house can cope with a total power demand of 65 amps, or about 14.7kW if you're on a normal 230-volt power supply. Which sounds fine (7.4kW is only half of that demand), but then you remember that a power shower can draw as much as 10kW when switched on, or an electric oven as much as 5kW, and suddenly you're crossing that power demand threshold. Do that and your trip switch will trip, and everything will shut down.

Because of all of this, it's important to get your house surveyed to check that your electrical installation can cope with the extra load demand of a car charger, and you might need to get a priority switch fitted, which can divert power to the area that's most needed, instead of throwing the trip switch.

It may be worth getting your electricity system upgraded to an 80-amp load, which would give you more than 18kW to play with. Equally, this is why it's best to charge your EV overnight: as total demand is much lower, you're unlikely to have your oven or shower or other high-load demand items switched on, and if you're on a smart electricity meter, you'll be able to get the cheaper overnight rate for electricity. It's also worth noting that electric car batteries draw their highest power demand when they start charging, and it tails off as the battery fills up. 

Off-street parking limitation

One crucial thing - you'll need a driveway, or some other form of off-street parking, as you're not really allowed to run cables across a public path. It's a major limiting factor for EV purchases at the moment, as it's all-but impossible to charge overnight if you don't have off-street parking, and preferably parking that's right next to the house. It's also preferable to have your parking spot as close to the electricity meter as possible, as this will reduce the need to run wiring through the house, lifting floors etc.

How much do car chargers cost?

Well, the good news is that, while chargers aren't necessarily cheap, there is a €600 grant available from the SEAI to defray a big chunk of the cost. Previously, that was only available to those purchasing an EV privately, but just recently it was expanded to include business and company car buyers (although it's worth noting that those buying commercial versions of electric cars - such as the Renault Zoe van and Hyundai Kona Electric van, are not eligible for the grant). 

Most charging point providers (and there are many, from Phoenix Electrical Services to EV Charging Ireland to iA Charger and more) don't quote a cost up front, preferring you to organise a personal quotation, but Electric Ireland lists prices of €499 for an 'untethered' charger, and €599 for a 'tethered' charger, both inclusive of the SEAI grant.

What does untethered and tethered mean? Basically, an untethered charger is a simple socket fitted to the outside of your house that's compatible with Type 2 charging cables - those are supplied as standard with most new EVs on sale. A tethered charger has its own integrated cabling, usually with a cable length of between three and five metres, and a Type 2 connection at the end. The latter is more convenient.

You can usually manage your charging by smartphone app, either one that communicates directly with your own charging point, or one that communicates with your car. These allow you to pick and choose charging times, taking advantage of lower electricity prices, or keeping away from high-load demand times, and also allow you to monitor your charging costs. There are also higher-end chargers with touchscreen controls and even face-recognition for locking and unlocking the sockets, but this seems to us to be gilding the lily more than a little. 

How much does a full charge cost? Well, that will of course depend on what electricity tariff you're on, and which provider you're with, but according to Staista.com, the current average cost per kWh (kilowatt hour) in Ireland is 26c. Now, you may well be able to get on a tariff that costs you much less than that, but taking the average, it means a full charge of a car with a notional 60kWh battery (cars such as the Volkswagen ID.3, Hyundai Kona Electric and Kia e-Niro are all in that ballpark) will cost you €15.60. 

You can very definitely cut that cost, though. Electric Ireland has a very cheap 10.49c overnight rate (albeit with a higher standing charge of €230, compared to other tariffs), which would give you a total charging cost of €6.29. Considering that a 60kWh car will generally have a fully charged range of between 350km and 450km, that's rather good going.

There are also options for making sure that your power supply comes from renewable sources or at least notionally so - both Ford and Volkswagen offer renewable energy power-supply contracts, via Bord Gáis Energy and VW's own Elli power company respectively. Along with that, many charger installers offer the option of fitting solar panels and even small wind generators.

You can still charge an EV from what's called a 'granny cable' - that's a Type 2 connector with a domestic three-pin plug at the other end. A domestic socket can provide around 2.9kW of charging power, but that's a terribly slow charge and isn't going to make much of a dent in a car with a large battery. It also means keeping a window or a door open (unless your house has an outdoor socket with suitable weather-proofing).

Looking for more EV info?

Here's our guide to buying a second-hadn electric vehicle.

Here's our twin test review of the Honda e versus Peugeot e-208.

Check out our guide to EV grants and incentives.