Electric vehicles are here to stay, and the closer you live to a main city the more likely it is that you will switch over to an electric vehicle in the near future.

When we do make that switch, most of us will charge up our electric vehicles at home — and that has implications for our self build or extension/remodelling project. You could either:

  • Plug the vehicle into a 13amp wall socket. The charge time for this would be 12 to 15 hours and even longer for larger batteries. There is a potential safety risk with this option, as an ordinary domestic plug could overheat or be a fire hazard if it’s old or unsuitable for the high loads required by an electric vehicle.
  • Install a dedicated charging point that usually has a capacity of 32 amps and a charging time of five to seven hours.

It is prudent to plan a dedicated charging point into your project and include it in the electrician’s brief, rather than retrofitting the products at a later date.

Installing a Charging Point for Your Electric Car

You have several options to choose from, including a universal socket for plugging a dedicated cable into, or a bespoke unit with a cable already fitted for convenience. Prices start at around £400 for a unit that will give you around 15 miles of range per hour of charge to about £1,700 for a unit that will give you 80 miles of range per hour of charge.

There are currently grants of up to £500 available for the installation of an electric vehicle charging point if:

  • you bought your electric vehicle after 1 September 2015
  • you have off-street parking
  • you have it installed by an installer approved by the Office for Low Emission Vehicles (OLEV).

Solar Panels and Your Electric Vehicle

If you have, or are planning to install, solar photovoltaic (PV) panels it makes sense to use as much of the generation as you can. An electric vehicle can then be fully charged for much of the year for almost free.

That would be fine if you happen to keep your car at home during the day. If you use your car during the day, you need to recharge the vehicle at night, when there is no sunshine. In this case it may be worth thinking about installing a battery system in your home. You can then charge the battery during the day and potentially use that battery to recharge your car at night, benefitting from any free daytime generation.

However, you need to make sure that your battery has the storage and discharge capacity required to recharge your vehicle in less than 10 hours. This is currently a challenge and may not add up financially. Current home battery systems cost around £5,000 for an 8kWh system and you could possibly require more than four times that if you needed to fully charge a car. The Nissan Leaf has either a 24kWh option or a 30kWh option if you need further range.

Home Battery Running Costs

Tesla has just announced the launch of its new home battery, the Powerwall 2, which comes onto the UK market in February 2017 and is expected to double the capacity of the smaller Powerwall 1 for less than double the purchase price:

  • The initial price of the Powerwall 2 on international markets is $5,500 for a 14kW system
  • The Powerwall 1 costs $3,000 for the 7kW system.

This larger capacity system could potentially be a game changer, as there could then be enough power to actually make a real difference in the average home and at a cost that hopefully represents a reasonable payback.

Tesla has aimed the Powerwall 2 at the mass consumer market and claims that it will be able to store enough electricity to power the lights, sockets and fridge in a four bedroom house for a whole day.

Nissan has also responded to the market for home battery systems and released the xStorage solution, which, like the Powerwall system, is a ‘second-life battery solution’. This means that the system uses the batteries that have already been used in Nissan cars and recycles them for use in home battery systems.

These systems can potentially enable the homeowner to have a battery storage system for their PV generation, whether or not they have an electric vehicle. They can also be used by those homes without PV systems to manage off-peak electricity tariffs by charging up the battery during the off-peak times and using the power during the higher cost periods.

This process of storing off-peak generation is currently frowned upon by the electricity suppliers, so make sure that it is compatible with your metering and wiring system as well as any future smart metering systems before committing.

In my opinion, it should be embraced by the electricity suppliers so that we then promote the use of off-peak energy and level out the usage patterns between peak and off-peak times.

Home battery systems have come a long way recently but clearly still need a lot of development in order to increase capacity and reduce initial costs. All manufacturers will have to stay competitive, so as production grows and uptake of electric vehicles and home battery systems increases the prices will hopefully drop somewhat, too. Keep an eye on this because someday we may look back and wonder how we managed without them.

David Hilton is an expert in sustainable building and energy efficiency and is Training Centre Sales Manager at HRP Ltd. He also delivers seminars at the National Self Build and Renovation Centre

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