Optimizing electric vehicle charger siting

The shift to electric vehicles (EVs) is picking up pace, and with that comes the need for substantial expansion in EV charging infrastructure. Determining the optimum locations for EV chargers will help to provide great driver experience, maximise return on investment and minimise the impact on the grid. Optimising EV charging infrastructure siting requires skillful application of sophisticated tools and techniques. The following article summarizises the anticipated growth in EVs and charging infrastructure and the value of optimising charger siting.

Electric vehicle revolution
We predict that by 2032, half the global sales of new passenger vehicles will be battery electric vehicles (see Figure 1 below), followed by commercial vehicles in 2038. The electric vehicle revolution has begun, with the next five years likely to see the highest rate of change.

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Figure 1, source: DNV Energy Transition Outlook 2019

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Three major factors drive the EV revolution:

  • Increasing urgency to address climate change (the ‘climate emergency’)
  • Pollution reduction measures in cities
  • Batteries with higher performance at a reduced price.

Charging infrastructure
In addition to the fundamental drivers behind the transition to EVs mentioned above, other factors influencing the decision to switch to an EV are vehicle range and convenience of charging (both location and speed of charging). In our EV adoption forecasting model, and our experience of more developed EV markets in Europe and the US, access to EV charging infrastructure significantly impacts EV adoption rates.

To support and help drive the EV revolution significant deployment of charging infrastructure is needed. Currently in Europe there are approximately 170,000 public charging stations, this is expected to grow to 2 million by 2025; similarly, in the USA there are currently 24,000 public charging stations, with plans for more than half a million by 2025. But how can this vast expansion in infrastructure be optimised, to ensure a great charging experience for EV drivers and efficient deployment.

The value of optimal charger locations
One of the benefits of EVs over internal combustion vehicles is that they can be re-charged while they are parked, although there will always be the need for a certain share of on route charging. In an ideal world, EV charging would be available exactly when and where it is needed. Although this utopia is unlikely to be the most efficient solution overall, it is certainly possible to optimise charging infrastructure deployment to bring value to all stakeholders by maximising utilisation and minimising cost:
Drivers – will have a convenient and timely charging experience, minimising disruption to their lives and smoothing the transition from a conventional vehicle. Optimal charger siting will also result in lower charging costs.
Charge point operators (CPO, also referred to as EV infrastructure provider) – achieve increased and more predictable utilisation of their assets, and lower grid connection costs. Can optimise their planned EV roll out, reducing the risk of stranded assets.
Investors – receive greater returns on their investments and reduced risk.
Distribution system operators – will have better foresight of the likely deployment of charging infrastructure on their system and the resulting load, enabling optimised investment in their grid.
Utilities/aggregators – (many of whom are also investing in CPOs), will be able to offer more valuable services to their customers and the grid if more vehicles are plugged in more often.
Car manufacturers – will also have better foresight of probable charger deployment and will have more satisfied EV customers and optimal e-mobility related services leading to more EV sales.

Charger siting optimisation
To optimise EV charger locations one must consider two major objectives, maximising utilisation and minimising cost. There are of course additional important considerations such as land/building availability, planning permission, government grants and other financial support, and equitable access to chargers for different sectors of society – but these are topics for another article.

Optimum locations for utilisation can be determined by answering the following questions:

  • When and where will EVs be bought?
  • Where will they travel?
  • Where will it be convenient to charge?
  • Where are EVs likely to reach 80% state of charge on longer journeys?
  • What speed of charger is likely to be needed?
  • How will this change over time with evolving technology: increased battery capacities, longer range vehicles, faster charging, shared transport and, in time, autonomous vehicles?

Optimum locations to minimise grid connection cost can be based on the following:

  • What are the power requirements of the chargers?
  • When will the power be needed?
  • What other localised load is on the system?
  • What is the current available capacity on the local Low Voltage (LV) and Medium Voltage (MV) network?
  • How are the factors above likely to change over the next decade?
  • What is the impact of the above on the grid connection cost?

By considering charger utilisation and grid connection cost, as highlighted above, the optimal locations can be found. Although charging infrastructure deployment includes a much broader set of factors, grid connection cost is strongly dependant on location, particularly for high power chargers.

To address the challenge of optimising EV charger siting, DNV and accilium have developed a range of service offerings and tools that take account of the key factors highlighted above. These include forecast models to support locational assessment of the potential adoption of EVs; DNV’s Synergi Electric distribution system model; accilium´s charging needs assessment tool; and benefit-cost analysis tools for alternative grid upgrade scenarios.

Synergi Electric is in use by over 200 utilities for distribution system modelling, and now includes the effects of EV charging on the grid. The charging potential assessment tool includes scenario-based calculations of electric car market ramp-ups for individual communities, and the resulting demand for charging infrastructure. An illustration of a combination of these capabilities used to optimise EV charger siting is shown in Figure 2 below.

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Figure 2 EV charger siting tool structure

An example of the output from Synergi Electric is shown in Figure 3 below, displaying localised remaining grid capacity. Visualisations such as this can be used to help determine where best to site EV chargers to minimise grid impact.

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Figure 3 Distribution system grid congestion

Figure 4 below shows the results from a DNV project, investigating the impact of EV charging on the local distribution system in the Netherlands. Simulations were run at hourly granularity, with green showing the correct voltage, blue showing undervoltage and red overvoltage. The results take account of EV charger locations, charger availability, charger power rating and charge duration, as well as consideration of rooftop solar PV installations. These results enable potential EV charger grid impacts to be analysed and possible solutions to be compared. For example, comparing the options of alternative charger locations, operational strategies such as smart charging and demand response, or grid reinforcement.

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Figure 4 Grid simulation of EV load

The efficient and effective investment in EV charging infrastructure is clearly a key aspect for a successful EV revolution. Optimal charger siting will maximise utilisation, minimise capital cost, improve the driver’s experience and increase value for all stakeholders. This is another aspect of the transition to EVs that is a catalyst for the automotive and energy industries to come together to reduce the barriers to an accelerated EV revolution. DNV and accilium have invested in enhancing our capabilities in this field, refining methodologies and tools to process increasing data volumes and improve certainty. We stand ready to support the industry in achieving optimal solutions for the vital transition to EVs and sustainable energy. If you have any EV challenges, questions about this article, or suggestions for the direction of tool development that would be most valuable for your organisation, then please get in touch.

The article was published by DNV in cooperation with accilium.

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2/20/2020 9:00:00 AM

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Jeremy Parkes

Jeremy Parkes

Head of Electric Vehicles Venture