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Analysis of EV charging in Ireland suggests public fast-charging infrastructure may become commercially viable in short- to medium term

A study of EV charging behavior by a team at Trinity College Dublin has found that, from the household data available, EV users prefer to carry out the majority of their charging at home in the evening—the period of highest demand on the electrical grid indicating that incentivization may be required to shift charging away from this peak grid demand period.

In their study, published in the journal Energy Policy, they also found that parking locations were the most popular location for public charging and that fast chargers recorded the highest usage frequencies. This indicates that public fast charging infrastructure is most likely to become commercially viable in the short- to medium-term, they concluded.

The study was based on an extensive analysis of public charge event data for the entire island of Ireland since the rollout of the public charging infrastructure began.

The analysis of household charging was based on a more limited quantity of household data.


  • Patrick Morrissey, Peter Weldon, Margaret O’Mahony (2015) “Future standard and fast charging infrastructure planning: An analysis of electric vehicle charging behaviour,” Energy Policy, Volume 89, Pages 257-270 doi: 10.1016/j.enpol.2015.12.001



If you look at the Irish Grid usage (Here)
You can see a peak from about 5-10pm every night when people come home for their "tea" (or "supper" if you are English).

However, if people then plug their Leaves in as soon as they get home, this will overlap with the peak which is not good at all.

They need a delayed charging system that will delay the start from about 10 - 11 pm (dither the start times so they don;t all come on at once). This should work fine for most people as an 8 hour charge will bring them to 6-7 am which is when you need the car next.

To "encourage" people to do this, you need a retail electricity pricing scheme which is (say) 2x the wholesale price + 5 cents / KwH for transmission.
You would have a box giving the price by the hour for the next 24 or 48 hours which would be enough to plan when to charge and wash clothes / dishes etc.

All you really need is to delay elective, energy intensive tasks till after 10 pm on weekdays.
[ If you want to boil a kettle of water at 5.30pm, just do it, if you want to wash a load of clothes, wait till 10pm - or heat your water with gas ]

It is that simple.

Nat Pearre

@mahonj: The solution is well established. EVs have charge start timers in them already, and a simple Time-of-Day (aka Time-of-Use) electric rate is very effective at pushing charging loads to when you want them.

There are lots of theoretical studies, but see here for an observational study: http://blog.opower.com/wp-content/uploads/2015/03/electric-vehicle-load-curve.png

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