EV Charging in the UK

[Rick C]

I'm being told EV charging will be a lot more difficult in the UK than it i s here in the US.

I looked at the typical daily cycle and they have some 10 to 20 GW between the peak and minimum each day with resonably flat consumption in the trough . That will allow off peak charging of a third of the 30 million vehicles for 50 miles.

But I'm being told there are two problems with that. One is that distribut ion is sized for an average of 2 kW consumption per household in many older areas (which they seem to have a lot of). This clearly makes it hard to c harge EVs overnight at just 3 kW which otherwise would be fine for a typica l user. In this case it would require replacement of a lot of distribution cabling.

The other is that many individual homes are on PME circuits where no separa te ground is provided to the home, only the neutral. This neutral is bonde d to water pipes and any other exposed metal that could be grounded my any means, like an old radiator heating system. This is considered safe since even if the neutral to the home opened there would be no shock hazard since there is no ground to make contact with as the grounds in the house are al l at neutral voltage. This does make it hard to use electricity outside wh ere you could contact a true earth ground and suffer electrocution with any grounded appliance. To mitigate this a ground rod at the house is require d which in many cases is prohibitively expensive to install with an adequat ely conductive path.

So are these two problems being presented realistically?

I'm also being told it will be a huge problem to provide enough charging ca pability for the many potential EV owners who park on the street or in publ ic facilities. I expect it is practical to install curb side and parking l ot outlets with some outlay which is small, in fact tiny compared to the co st of a car. But I kinda have to take them at their word for that one.

Rick C.

[Cursitor Doom]

Rather than have guessing games among Americans as to what the situation in the UK is, just ask the Brits direct!

[Winfield Hill]

Well, R.C. was told, so we'll just have to leave it at that.

[John Rumm]

That does rather assume there is not also a move to shift domestic heating away from gas or oil to electric. We would certainly need more generating capacity for any significant shift.

Distribution networks are sized based on statistical models - so they will calculate an average load over 24 hours to assess total demand. However they do also anticipate significantly higher peak demands. New properties are typically built with a 24kW electrical supply (1 phase,

100A, 240V). Older properties may have 80, 60 or in some cases only 40A supplies. Typical home charging stations will run at 6kW, although those with smaller EVs may opt to use a 13A (~3kW) charging lead plugged into a socket. As EV battery capacities grow this kind of charging solution may become less practical for some.

PME (Protective Multiple Earthing) distribution systems supply the property with a "PEN" conductor - Protective Earth and Neutral. This is the main neutral as derived at the substation - however as its name suggests it is bonded to earth at the substation, and then at regular intervals along the distribution network. Its the preferred solution for new supplies since it delivers a reliable and low impedance earth path. Many older properties however will have TN-S earthing systems, (i.e. separate earth delivered from the sub station to the property). Older rural properties may well have no earth supply from the network at all (TT systems)

For more detail see:

Generally more caution is used when exporting a PME earth to outside circuits. The risk of neutral disconnection (and not line also) is considered a fairly low likelihood event. However precautions taken typically include extending the equipotential zone to where you are exporting power. This is not ideally suited for EV charge points outside.

No not really. In many cases you simply convert to TT with local RCD (GFCI). Hence any ground rod only needs a stable earth impedance under the low hundreds of ohms, and that is relatively easy to achieve.

See:

Note also that there are specific additional rules for EV charging point protection (special classed of RCD etc) designed to mitigate some of the perceived problems.

Street charging is a more difficult problem to solve without significant new infrastructure. Hopefully at some point there ought to be a larger network of fast chargers that can be used to charge on demand, rather than overnight. Making for something closer to the current normal practice of stopping off at a filling station to refuel.

[Martin Brown]

The number he has might well be right as a time average across a year for a household. Typical numbers for various sorts and sizes of UK house are online here in terms of energy use in kWhr per household per year.

It is about 3-4MWhr per year per household or 8-11kWhr/day on average.

That translates to a 300-500W average daily load which seems a bit high to me. My own daily peak load is about 350W average and night time base load is well under 100W unless I am running something on the computers.

Interesting that several green sites quote the 6kWhr/day figure when working out how many homes a new green energy PV farm can supply. (at least when the sun is shining or the wind blowing hard enough)

But I am fairly sure that the distribution system is good for delivering considerably more than that as peak transient load without any problems at all. It happens with 3kW kettles at half time every cup final day.

They have to prep the generating system ready for the exact moment and then engage the rapid response kit and pumped storage at full tilt.

[Cursitor Doom]

[...]

Thanks, John. Nice to have advice from someone that actually knows what they're talking about for a change.

[Winfield Hill]

I can charge on the street, if I can park within two car spots of my driveway. Apartment dwellers in a crowded city have a problem. Several are like that here at work, but they can charge up in our garage.

[Brian Gaff]

I'm a little worried about charging devices on lamp posts. With the idiots we have, I'd fully expect these to be vandalised in short order. Brian

[John Rumm]

Its the transition that will probably be most problematic where only some on street parking spots have access to a charger, and lots of those get blocked by IC engine cars.

[krw]

You're allowed to put a power cord across the public right-of-way (sidewalk, boulevard, etc.)?

[krw]

Seems like a business opportunity here. Block access and move for a "small" fee. Much better than a lemonade stand (cities are cracking down on those).

[John Larkin]

Product idea: an outlet sort of like a GFD, but it cuts off if too many KWH are used in some time period. For garages and motels and things that don't want electric car owners stealing their power.

[Steve Wilson]

You have been driving for hours, check into a motel and find you cannot recharge your car?

Go across the street to another motel that advertises charge hookups. Just add the cost to your room bill.

[John Larkin]

Sure. You could pay extra for some KWHs.

Free fuel is really appealing to some people.

If they advertise free charging, then it's not stealing.

I've never seen that, but I suppose it happens. The motel might need to upgrade their service and wiring to handle everyone plugging in. They certainly don't want extension cords running out of doors or windows into the parking places.

[Steve Wilson]

That's what I said below.

I never said free charging.

They have to recover their cost somehow. One way would be to offer charging hookups only in premium rooms. Not everyone will be driving EV's

- ordinary motor vehicles will be around for a long time. They won't need a charging hookup, so there is no need to charge extra.

Anyway, there is no need for your product idea that "cuts off if too many KWH are used in some time period."

Just insert your room key to start the charger. Have it stop the charging automatically as soon as you unplug your car. Add the cost of electricity to your room bill.

[dennis]

They do that a lot in ikea.

It wouldn't happen as much if they didn't put the charging spaces next to the door.

Pretty soon they are going to be in trouble as the spaces are too small for disabled spaces so they have no charging spaces for the disabled.

[John Rumm]

No, can't see that being looked upon favourably. There are a few kerbside charging points on the street though.

Here is a relatively new example:

[Andy Burns]

Wonder if the council has been sued for installing these trip hazards yet?

[Tim Streater]

Scrotes will learn to fill them with superglue or other more witty substances.

[John Larkin]

Ugly asphalt strip on an old stone sidewalk too.

They will fill with rain, dirt, trash, dog by-products, and get run over by every possible vehicle. Skateboarders and bicyclists and people in wheelchairs won't like them.

But hey, the mayor approves.