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EV charging infrastructure needs a new strategy driven by user needs

For people to buy EVs with confidence, they need slow chargers where they park and ultra-fast chargers at service stations. Today’s rapid chargers will become obsolete.

Jean is one of many Londoners who parks her EV on her street overnight. Every few days, she drives two miles to the nearest ‘rapid’ charging point, where she queues for half an hour to charge her car, which takes up to an hour.

Over 30% of people in the UK don’t have a driveway where they could install a charger. For them, this is the hassle that comes with owning an EV. Some still buy for environmental or cost reasons, but many see long charging times as a major disincentive to adoption.

And yet these ‘rapid’ chargers are attracting the bulk of public and private EV charging investment.

This strategy is misguided. As we will demonstrate in this article, the best way to support EV uptake is a dual charging system, matched to driver needs. This would see the majority of charging done by slow chargers where people already leave their cars for long periods (eg overnight or at work); and the rest by ultra-fast chargers (~10 minutes) at service stations for long journeys and emergencies.

How do people want to charge their cars?

To understand how charging infrastructure should evolve, we should first consider how people use vehicles.

There is an inclination to view EVs like petrol and diesel vehicles, where people go to a service station to fill them up. But this scenario evolved because people could not pump petroleum into their homes. Electricity on the other hand already flows through buildings and streets and simply needs to be tapped.

A better analogy is to smartphones. Most people do not need rapid phone charging all the time, but instead charge at fixed locations, eg overnight or whilst at work. They may wait somewhere inconvenient to charge them occasionally, such as when away from home, but this is the exception.

Like phone users, given the option, EV drivers prefer to charge their cars within their daily routine when they can plug in and forget about it. This is borne out amongst those with access to home charging stations, who do over 80% of charging at home .

The problem with the current approach to EV charging

Investment in EV chargers has been mostly focussed on 22-50kW ‘rapid’ chargers, which take between 45 minutes and three hours for an empty to full charge. The problem here is that, with few exceptions, these charge times don’t mirror the periods of time people leave their cars parked.

Only about 3% of charging is done at rapid chargers . A better solution would be slower, less expensive chargers where people leave their cars.

It is rare for people to park their car for the exact charge time they need as part of their daily routine. A one-hour charge forces them to wait, or return at a precise time in order to avoid extra charges. By contrast, if the car is going to be parked there anyway, an eight-hour 3-7kW charge requires less dedicated user time and effort than a one-hour charge, as the user simply arrives, plugs in and goes about their daily activities without further thought about charging.

The average car spends 80% of the time parked at home. Travel to work is the most frequent reason for parking away from home (outside London, 70% commute by car). Although a large proportion of parking is short term in public car parks, this tends to be of an ad hoc, unpredictable nature for shopping and recreational activities. Workplace parking, on the other hand, has a consistent pattern and an average duration of 7.6 hours - about the time it takes for a full charge using a 3-7kW slow charger. Home and workplace parking are predictable and long duration, making them ideal for inexpensive slow charging infrastructure.

Rapid chargers are not fit for the future

Rapid chargers also raise questions about long term viability.

Long queues, especially at peak times are likely to be a significant problem. A Tesla Supercharging Station between Los Angeles and San Francisco – a hotspot for early adopters – faced hours-long queues during Thanksgiving .

UK EVs could rise from 200,000 in Q4 2018 to as high as 10.6 million by 2030 - almost 1 third of vehicles on the road. Some of that will come from people without driveways, especially in places like London where the congestion charge discount provides a big incentive to switch. As electric vehicle numbers rise from the current 2%, investment into rapid chargers will have to increase multiple times over just to maintain current queue lengths. Unless an alternative approach is deployed.

Rapid chargers are also bad for EV batteries. The surge of power creates strain on the battery which reduces capacity over time (and secondhand value), and so weaken the financial case for EVs. Slow trickle charging preserves battery integrity for much longer.

Rapids are also comparatively expensive. Those without driveways – disproportionately located within urban areas and often associated with lower income demographics – therefore face higher costs of running EVs. This entrenches a two-tier system, where wealthy people with driveways have EVs, and poorer people are trapped with petrol and diesel vehicles, paying more to run them and breathing more polluted air.

Longer term, demand for rapids will decrease. As EV range increases there will be little need for mid-journey charges. The average commute is 10 miles, whilst the Tesla Model S can already do 335 miles on a single charge.

What is the future of EV charging points?

Rapid chargers provided a short-term solution whilst EVs were in their infancy. Now that the range EVs can cover has increased to consistently above 200 miles and they are recognised as a vehicle of the future, there is a need for charging infrastructure suited to mass EV ownership.

This should be driven by dwell time, not speed of charging. Drivers want EVs to be charged when they leave their house or work. Occasionally they want to charge mid-journey, and they will want that to take a maximum of five to ten minutes – the time it takes to grab a coffee and visit the bathroom.

The current message to EV owners is ‘it’s nearly as convenient as a petrol car’. This is unlikely to resonate beyond early adopters. A better message is ‘your car will always be fully charged when you get in it’.

To be able to deliver this message with conviction to those reliant on public charging infrastructure, there is a need for a polarised approach to charging infrastructure.

At one end, this means providing access to affordable, slow charging where cars are parked for long periods, via the installation of large numbers of unobtrusive slow chargers on residential streets and in car parks near offices.

At the other end there is a need for ultra-fast chargers at service stations – 150-300kW, which can deliver a full charge in under 10 minutes – enough time to get a coffee. These will serve those on extremely long journeys (particularly commercial drivers), or those who mis-planned.

Overcoming challenges

There are challenges at either end of the spectrum. Expensive ultra-fast chargers will need business models aimed at near-constant use to make them financially viable in a world of fewer customers as range increases – eg a motorway petrol station model.

At the slow end, planners need to consider chargers impact on the street, ensuring they provide maximum accessibility, but don’t create unnecessary clutter. To avoid restricting adoption, the roll out will need to be planned to be ahead of the pace of uptake, to ensure those buying EVs can do so in confidence they will have access to charging at the time and in the location where they need it.

These are all manageable challenges. Most of the world successfully deployed broadband infrastructure ahead of demand. Amsterdam has put chargers in most public parking spaces.

The main limiting factor is mindset. Most approaches to EV charging focus on small numbers of ‘refuelling stations’. Deployment is piecemeal – 5-10 points here and there. The ambition needs to be bolder and longer term. The 100-odd local authorities that have committed to 100% clean energy by 2050 match that ambition with a strategy designed to achieve it. Providing an infrastructure that effectively facilitates a rapid transition from fossil fuel vehicles to EVs would go a long way towards doing so.

For EVs to become mainstream, people need to feel that the switch will be cheaper and more convenient, which means charging deployment needs to be aligned to the reality of people’s existing routines. Many local authorities have already shown bold thinking in their emissions reductions commitments, now they need to match this with strategic, well-planned approaches to EV charging infrastructure.


2016 English Housing Survey: 38% of dwellings had a garage, 28% have other off-street parking, 18% adequate street parking, 14% inadequate street parking, 2% no parking provision.