There have been a few negative posts about the impact of EVs on the Grid recently. Soapbox ahead…..

As a general observation, I keep noticing the authors using total installed load with no diversity.  A recent posting suggested extra, large capacity, power stations would be required to cope. At this stage no-one really knows what the impact will be.  Most of the commentators use a sum of battery capacity and a sum of charger rating.  

A pragmatic view is that not every user will connect at the same moment, nor will they all need to charge, or charge fully, every day. 

 The period that I’d highlight as a potential issue is  between 17:00 & 22:00.  This time window at the end of the working day would see a significant rise in load if everyone plugged in at once.  A simple means of avoiding this to have charge timers set by default by the manufacturer to start at intervals after 22:00.  All the OLEV funded home charge points have Smart metering, so there is already profiling data on when charging is happening.  It would fall to the various supply and network companies develop strategies to manage network loads. The two that I believe will come first both depend on Smart metering.  Both target consumer behaviours that are well documented.

Simplest first, time of use tariffs.  Off peak heating tariffs would evolve to include charging.  The added flexibility available from Smart meters would offer easy staggering of the periods, with the users notified of any changes by the Home Display Unit that comes with each meter.

Second comes integrated active time of use.  Each Smart meter will be capable of direct load control.  So the Grid operator at both local and national level will be able to start and stop charging.  This would mean that the network operators could start charging early if for example, there was an excess of wind generation, or postpone charging while waiting for a power station to come online, or for a local network limitation to be resolved.

Expect to see a much more complicated looking electricity bill in the future, with itemised pricing for different time slots.

Naturally the timing won’t suit everyone, so there would be an override function. Naturally, at a price.

It’s a massively complex, evolving area. As technologies like Vehicle to Grid (V2G) become commonplace it will change again.
Right now though, as EV owners, we can start to make changes to how we charge.  Set the timer on your car at home.  Set it so that you’ll be ready to go first thing.  Don’t need to charge, don’t plug in.  Tonight I reached home with more than 80% in the battery.  The handbook does recommend not charging until below 80% anyway, tomorrow I’ll be unlikely to do more than 50 miles.  With 7 rapid chargers on my route, a change in plans is easily managed.  So, tonight the car isn’t plugged in, although I have set a one off timer on the climate control, it is a bit cold out there.


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Engineer, EV driver, dog owner.

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