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If electric vehicles are the future, how will that affect the electricity demands of a site?

Eleanor Wratten \ 18th Oct 2019

Last year, the Government announced it was consulting on proposals to ensure that all new-build homes should be fitted with an electric vehicle (EV) charge point. The current proposed polices are:

  • Every new residential building with an associated car parking space to have a charge point
  • Every residential building undergoing major renovation with more than 10 car parking spaces to have cable routes for EV charge points in every car parking space.
  • Every new non-residential building and every non-residential building undergoing major renovation with more than 10 car parking spaces to have one charge point and cable routes for an EV charge point for one in five spaces.

Assuming these proposals go ahead developers will need to consider at an early stage the implications this will have on the electricity capacity requirements for their development.

Domestic capacity requirements

Currently, a typical gas-heated home on a large development of 500 homes, for example, would need an allowance of 2kVa after diversity. Peak diversified demand for the scheme would be in the order of 1MVa total, which would require one new dedicated distribution substation onsite to serve the development. As a rule of thumb, you could expect a new substation to cost in the region of £35,000 - £60,000 depending on location and other infrastructure requirements in the area. This cost could be significantly higher where network reinforcement is required or if the site is remote.

Once we start factoring in EV charge points, this load demand starts creeping up very quickly. This is before we even consider the move towards the electrification of heat.

EV charge points come in a few different power ratings, depending on how fast they charge a car:

Most homes are likely to be fitted with a 3.5kW or 7kW rated charge point as these need a standard single-phase supply that is installed in domestic properties. Using our example of a new 500 home development, this could lead to a more than doubling of electrical demand to the development to support the charge points.

Very quickly, the development might need two or even three substations instead of one. This not only triples the cost of the new connection but also takes up valuable developable land inside the development.

Transition to electrification of energy

Legislation changes are encouraging a transition to electrification so that the UK can meet its climate and carbon targets, and so consequently we need to look at smarter ways to bring energy to the site and reduce the connection demand needed from the National Grid. For example, combining solar PV and battery storage in each home, which can then be used to help charge electric vehicles. There are a number of installers and energy companies looking at these innovations and incorporating ‘time of use’ tariffs so that homeowners can benefit from off-peak electricity prices to charge their cars, providing a financial saving whilst also helping with balancing the grid at times of peak demand.

Most domestic users are likely to come home and charge their vehicle over night during off-peak hours, which will help balance the peaks and troughs of electricity demand. There are also innovations being looked at for vehicle to grid charging, where car batteries are connected to the national grid and stored energy can be taken from the car and into the grid where needed. This is known as Demand Side Response (DSR).

As more and more local authorities are declaring climate emergencies and planning policy is responding to reflect this, we are seeing developers needing to consider alternative ways to power their site rather than relying solely on a standard grid connection.

Using our expertise in utilities and smart energy at Hydrock, we’re able to provide guidance on suitable options for developments, looking at a range of factors including financial costs/incentives and carbon targets. This can include funded delivery options in addition to potential revenue schemes.

This article was originally published by Eleanor Wratten on LinkedIn.