Economy 7 metering query

[Iggifer]

Solar PV + Tesla Powerwall + Electric Car = free fuel for the car.

It’s clever in that it charges the powerwall up during the ‘sun’, and then dumps what charge it has managed to acquire into the car.

Obviously it’s a lot more complicated than that as it does your whole house and you probably need a Tesla to take full advantage but it’s definitely the future.

Now if I only I had a spare £200K......

 

[flameport]

Solar PV + Tesla Powerwall + Electric Car = free fuel for the car.

Only if you use the car very little, have a gigantic array of solar panels, and it's sunny most of the time.

Smallest Tesla car battery 60kWh. Most are more.
Typical domestic solar panel installation 3kWh peak.
Sunshine per day - maybe 10 hours if it's the middle of summer and there are no clouds. Far less at other times.

A Nissan Leaf has a 30kWh battery so a full charge of that might just about be possible a few times a year.
Newer designs of electric vehicles have larger capacity batteries to provide greater range and/or power.

 

[JohnW2]

It seems quite possible that the current waveform of EV chargers is known, and is sufficiently different from other long-term loads for a different tariff to be applied.

Even if EV chargers (or whatever) did have a unique current waveform, I don't think that the current generation of smart meters (which themselves seem to be taking decades to 'roll out') have the ability to undertake waveform analysis, do they?

Kind Regards, John

 

[stillp]

Even if EV chargers (or whatever) did have a unique current waveform, I don't think that the current generation of smart meters (which themselves seem to be taking decades to 'roll out') have the ability to undertake waveform analysis, do they?

Hardly what I would call "waveform analysis", but I've been led to believe that some at least can recognise 'patterns' of current consumption.

 

[EFLImpudence]

Do the meters have to 'recognise' anything?

Surely they just 'report to base' when asked and analysis of usage, if not waveform, will be done there to tell the meter what rate to charge.

Presumably addresses of EV owners will be known.

What about night-shift workers (taxi) who charge their car during the day?

 

[ban-all-sheds]

What about the pretty-simple idea of just requiring all EVs to negotiate with the charger? No negotiation, no charge.

 

[Aragorn84]

The powerwall+solar works because people dont on average drive that far. Most journeys are under 5 miles, and the average UK driving is around 8k a year.

So for many drivers, your not actually needing to charge the 30kwh battery up from flat. Your only needing to top off the 5 or 10kwh that you've taken out of it that day. And thats perfecly achieveable with a typical UK solar installation, in the summer at least.

I commute around 80miles twice a week, so clearly those days the car needs a full charge, but the rest of the week the wife uses it and it doesnt generally need charged at all. Occasionally we'll make a trip at the weekend, although often we'll use the petrol car at the weekend to give it a run.

 

[Aragorn84]

What about the pretty-simple idea of just requiring all EVs to negotiate with the charger? No negotiation, no charge.

They already do negotiate with the charger, as they need to check the charger and cables maximum current capacity, and perform a handshake before the charger will close the main contactor. But its a fairly simple protocol thats standardised worldwide.

https://en.wikipedia.org/wiki/IEC_62196

The protocol is simple to minimise "issues" and make the equipment as robust as possible for automotive use.

A more advanced protocol could ofcourse be implemented, but then theres various connectivity and reporting issues that come along.

 

[JohnW2]

Hardly what I would call "waveform analysis"...

OK, but whatever you want to call it, it was you who suggested that the current waveform of an EV charger might be known, so presumably that waveform would need to be in some way 'examined' (if you don't like 'analysed') to see if it corresponded with the 'known waveform' of an EV charger?

.... but I've been led to believe that some at least can recognise 'patterns' of current consumption.

It sounds a bit like a bag of worms to me, unless the load in question actually 'identifies itself' to the meter and/or supplier. I would imagine that anything like a system of 'pattern recognition' would lead to any number of disputes about the rate being charged for a certain period of usage.

Kind Regards, John

 

[JohnW2]

Do the meters have to 'recognise' anything? Surely they just 'report to base' when asked and analysis of usage, if not waveform, will be done there to tell the meter what rate to charge.

Maybe, but do the current generation of smart meters even have that capability.

EV changing is a pretty special case, in that it results in a high and persistent power consumption that is presumably not hard to spot (although the system would have to be able to distinguish between EV charging and storage heaters). However, a lot of people seem worried about Big Brother getting involved with much more 'ordinary' loads, and it's hard to see that they will/would be able to identify them unless/until we have 'smart appliances' that can be interrogated.

What about night-shift workers (taxi) who charge their car during the day?

Who knows? The electricity suppliers could well say that the lifestyle and life patterns of consumers are not their problem!

Kind Regards, John

 

[stillp]

What other loads might there be that have a 'spiky' current waveform and high current, that persists for several hours?

 

[JohnW2]

What other loads might there be that have a 'spiky' current waveform and high current, that persists for several hours?

I don't know - quite probably none. As I recently wrote, EC chargers are probably fairly easily identified, but the same is not true of most of the other types of load that some people fear Big Brothe will be monitoring and maybe even 'controlling'.

Another thing that seems to get overlooked is the fact that (at least with current installation infrastructure) the currents being drawn by all loads arrive at the meter through the same cables, as a single 'composite' current, which presumably would/will complicate matters. What if, for example, an installation is powering both an EV charger and storage heaters during the night. The system may well be able to find strong evidence that an EV charger is part of the mix, but working out how much of the total current is attributable to that load, and 'meter' it separately, could well be a challenge.

A 'smart' EV charger could, I suspect, not only 'identify itself' but also 'report' how much power it was consuming. However, creating a reliable IT system that could constantly monitor 25 million (or whatever) electrical installations would presumably be a far from trivial task.

When one considers how long it takes us to build a railway line or extra runway capacity at airports or device an NHS-wide IT system that actually works, I do wonder whether there is much prospect of much of these feared happenings getting very far this century! It's certainly not something that I personally am going to loose any sleep over!

Kind Regards, John

 

[ban-all-sheds]

They already do negotiate with the charger, as they need to check the charger and cables maximum current capacity, and perform a handshake before the charger will close the main contactor. But its a fairly simple protocol thats standardised worldwide.

And easy to extend, in the time available (decades, probably), so that a car simply will not charge unless via a proper charger, and hey presto - no problems identifying EV consumption.

 

[JohnW2]

And easy to extend, in the time available (decades, probably), so that a car simply will not charge unless via a proper charger, and hey presto - no problems identifying EV consumption.

Yes, but as I recently wrote, identifying the fact that part of the installation's prevailing consumption is due to an EV charger is only the start. One then has to somehow determine how much of the total consumption is attributable to the EV charger, and then find a way of metering that component. With current installation wiring and meters, I don't see how such metering could be done locally.

Kind Regards, John

 

[Aragorn84]

And easy to extend, in the time available (decades, probably), so that a car simply will not charge unless via a proper charger, and hey presto - no problems identifying EV consumption.

So what happens when you drive to france/ireland (or anywhere else)? The special UK modified protocol then doesnt work, your car wont charge and your stuck.

Or, someone just invents a widget that connects between the car and outlet which tells the car what it wants to hear, and it'll start charging just fine.

My view is simply that the model will change.

We cant apply ICE thinking to an EV. Instead of trying to think of it like petrol or diesel, metering the fuel, and trying to charge per "litre", some other scheme will be invented, which is perhaps based on mileage or per-road charging using a GPS type system a bit like current insurers are using for new drivers. Or the whole thing will be completely restructured in ways we havent even considered.