This article is about the UK “Electric Nation” EV Smart Charger Trial, in which I participated.
Approximately two years ago I heard about a scheme in the UK in which I could get a home charger for free. Always keen for a bargain, I enquired about it. It turned out that Western Power Distribution wanted to conduct a survey of electric vehicle charging at home. Western Power Distribution (WPD) is the distribution network operator for the UK Midlands, South West England, and South Wales. It is responsible for delivering electricity to approximately 7.9 million customers in the UK, and is committed to investing around £1 billion on its network annually. They were keen to get some real data, from which they could evaluate exactly how electric vehicle charging at home would affect the local supply system.
Detractors, looking for something negative to say about electric vehicles, have often said that the entire grid would have to be upgraded, local substations would never be able to cope with the increased load and hundreds of power stations would need to be built to supply all the extra electricity. I remember Ecotricity did their own survey and concluded that if every car in the UK was replaced with an electric vehicle it would only take about 13% more electrical power to supply all the electricity they might be expected to use.
However, it can be more subtle than that. For example, if all electric vehicles only charged up during the night when most people are asleep and electricity demand is very low, far from requiring extra generating stations, it would provide better utilisation of the generators we already have. There is also the concept of a smart charger. A smart charger has communication links, so information about its usage can be transmitted, stored, and analysed. Those same links can allow the charger to be remotely controlled. This not only allows the distribution company to know exactly how and when electric vehicle chargers are being deployed in its area, but also allows the company to control all of the chargers, to prevent any overloading of the local electricity grid.
That same smart capability can also allow the owner of the charger to control it through a smartphone application. They can also get information from their charger transmitted to their smartphone. For example, having set the vehicle to charge, they can monitor progress from the smartphone. Also, they might plug their vehicle into the charger but set the charger to switch on at a specified time. That time is likely to be at some point during the night when cheaper electricity is available.
When I signed up for a free charger, I also signed up to be an active participant in the survey, and this was a condition of getting the charger for free. The survey project is named “Electric Nation,” which, unknown to me at the time, is the largest smart-charging trial in the world. The project has been collecting data to expand understanding of the impact of the home charging of EVs on the local electricity network and to evaluate the reliability and acceptability of smart charging for EV owners.
As part of the programme, I also allowed a tracking device to be fitted to the car, so that the study team would have full information about the extent of my use of my electric vehicle, as well as charging events. It was a downside to the programme that I had to have my Wi-Fi switched on 24 hours a day, 7 days a week. Previously, I would only have it switched on when I actually wanted to use it.
It was not long after signing up that an engineer arrived and installed the charger and communications equipment, all connected to a dedicated 32 amp line. I now had the advantage of a much faster level 2 charger for my car, having had only a 10 amp charger before, plugged into an ordinary domestic socket. The distribution company from that point on was able to gather data on exactly when I used it, the level of charge at the start and end of each session, how much current flowed, and how many kilowatt-hours I used each time. The distribution company was also able to reduce the amount of current available, if necessary, or even stop charging altogether.
They provided me with a feedback system, so that I could tell them about regular journeys and any one-off trips to ensure that my car was always charged sufficiently to complete all of those journeys. At one time, they introduced a system where I could earn financial rewards by charging at off-peak times. I pay the same for my electricity regardless of what time of day I’m using it. There is no particular incentive, therefore, to use it at off-peak times. However, the incentive scheme did give me a reason for delaying charging sessions to the nighttime. Where previously I had tended to just plug in whenever I got home, I started to leave charging until before I went to bed, unless I was going out again and needed to charge. I did quite well with their financial incentives and ended up with a nice stash of Amazon vouchers to treat myself with.
The survey is now complete and Electric Nation is publishing initial findings. It’s also continuing analysis of the data with further reports to come. Although I have, in a lighthearted way, suggested that my only interest in the programme was getting a free charger and Amazon vouchers, I was very excited to have the opportunity to take part and was genuinely interested in the success of the project. I told them that I am writing an article about it for the online magazine CleanTechnica and asked for any comment, but I have received nothing extra from them.
The following is taken from their website:
Local Electricity Networks & Electric Nation Trial
The Electric Nation project is focusing on the local electricity networks that are run in a safe, secure, reliable, and sustainable way to provide energy to local communities. This trial will help Distribution Network Operators (DNOs) to increase their understanding of the impact of EVs on their networks, and how this impact could be reduced using smart chargers.
Objectives Of The Project
The Electric Nation smart charging trial aims to:
- Expand current understanding of the impact on electricity distribution networks of charging a diverse range of electric vehicles at home. This project is seeking to discover how the impact will be altered by different types of vehicles with different sizes of battery that charge at different rates.
- Build a better understanding of how vehicle usage affects charging behaviour given diversity of charging rate, and battery size.
- Evaluate the reliability, and acceptability to owners of EVs of smart charging systems, and the influence these have on charging behaviour. This will help to answer such questions as:
- Would charging restrictions be acceptable to customers?
- Can customer preference be incorporated into the system?
- Is some form of incentive required?
- Is such a system ‘fair’?
- Can such a system work?
Smart charging services in the trial are being provided by CrowdCharge, and GreenFlux. The learning from this trial will be used in the development of tools that will help DNOs procure smart charging services to protect low voltage networks from high EV charging demand.
In addition, the data gathered in the trial is being used to develop EV charging profiles for a low voltage network assessment tool that will enable Western Power Distribution to forecast the impact of EV uptake on the low voltage networks across its operational area.
The Electric Nation smart charging trial is now complete, ending in December 2018, with the reporting, and development of tools, and project outputs by October 2019.
Further information about the project findings to date can be found on Western Power Distribution’s website.
Participant Customer Research
Electric Nation has recruited 673 plug-in hybrid, and full electric vehicle drivers into the trial, each equipped with a smart charger at their home. The primary driver of the plug-in hybrid, or EV, charged using the smart-charger is asked to complete customer research surveys at key points in their journey through the trial. While they are not representative of the driving population as a whole, they will enable the project to draw observations, and conclusions relating to driver attributes, charging behaviours, and acceptance of smart charging.
Throughout the trial, In spite of many drivers experiencing regular EV demand management, 95% of the trial participants remain neutral, or satisfied with their current charging Arrangements.
The project is learning a lot about drivers’ charging behaviours by using data from their smart chargers to understand the potential mass impacts on electricity distribution networks, and how these might change depending on plug-in vehicle types, and battery sizes in the future. This enables the results of the trial to look to the future as battery EVs evolve, and the mix of plug-in hybrids vs battery EVs changes.
The time of day when EV drivers plug in to charge, and the amount of energy they consume, (how long they charge for), is vitally important to understanding EV charging load diversity.
Figure 1 illustrates the difference between weekday, and weekend EV start-of-charging, (includes delayed charging through use of timers).
If unrestricted charging was allowed as soon as an EV is plugged in then the predicted increase in peak domestic electricity demand on weekdays due to EVs is obvious. However, Electric Nation has found that EV drivers do not charge their EVs every day, and nor do they all wait until their battery is empty before charging.
Figure 2 shows the spread of average proportion of the battery capacity consumed by each participant in charging their EV,(e.g. a charge session consuming 20kWh of electricity for a vehicle with a 40kWh battery capacity = 50%).
Trial data suggests that the bigger the vehicle battery, the less likely that it will require a full charge when it is plugged in. This significantly contributes to the diversity of EV charging behaviour. A significant number of the Electric Nation trial participants use their EV’s on-board timer to take advantage of Economy 7 type tariffs.
Figure 3 illustrates use of timers by trial participants.
Trial participants with dual-rate meters (who can use Economy 7 type tariffs) are more likely to use a timer to charge overnight than those who have single rate meters – pointing to time of use tariffs as a way to incentivise EV charge management, and reduce charging during the current evening peak in domestic demand.
This understanding of how simple time of use tariffs, like Economy 7, impacts charging behaviour indicates how smart meter- enabled time of use tariffs could contribute to avoiding EV charging at the peak domestic electricity demand period.
Smart Charging In Action
Figure 4 is an example of analysis of the CrowdCharge smart charging system in action. The main graph shows the percentage of days (and weekdays, and weekend days) that charge management occurred during May/June 2018. The inset graphs show the average (weekday, and weekend), and maximum/average/minimum weekday current limits during charge management events.
This type of analysis allows Electric Nation to quantify the impact of smart charging on individual customers, and reference this back to the customer research, and other customer interactions with the project team, to fully assess the acceptability of smart charging for low voltage network protection.
What We Have Learned, So Far
“One of our major concerns was that everyone with an EV would drive home, and plug their charger in straight away, adding to peak period load,” said WPD Innovation, and Low Carbon Networks Engineer, Ricky Duke. “That might have required a £2.2bn investment in upgrading LV networks across Britain by 2050, which would have created a hidden cost to EV ownership. But Electric Nation has revealed that participants are adapting existing behaviours. Being cost conscious, and setting timers to coincide with lower rates creates a spike but is well within network capacity, although it may prove an issue for generators.”
Another question the Electric Nation trial seeks to answer is whether smart charging will be acceptable to customers, particularly at peak times.“The answer seems to be ‘yes’ provided they all still get the amount of charge they require by the time they need it,” said Ricky. “So reducing a 7kW charge to 6.5kW shouldn’t be an issue.”
Electric Nation will be revealing its full findings at a summer seminar. Details will be available here: Electric Nation Project.
All images via Electric Nation.
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