Smart Meter Time Accuracy with ToU Tariffs

JKenH

I came across this issue on Facebook and thought it might be worth repeating here. Has anyone had this type of problem?

MeteredOut

The thread title and summary "smart meters are not smart at keeping time" are both misleading. They have a process for updating their their time after a power cut, but something obviously went wrong in this case.

So, worth highlighting, but these incidents are isolated.

JKenH

The Guardian reported on it 12 years ago.

Faulty electricity meter clocks 'could be costing households thousands' | Energy bills | The Guardian

Keep_pedalling

SMs have are equipped with a battery or capacitor that maintains the meter’s clock in the event of a power failure so it should not happen unless the meter is faulty. We have been using an EV tariff for nearly 7 years in two properties (SMETS 1 in our previous house SMETS 2 in our current one) and the few outages we have had have not caused any issues with incorrect billing.

JKenH

I have had a smart meter for a similar length of time with no problems even after power cuts.Because we haven’t had a problem doesn’t mean others haven’t or won’t. While the problems may be isolated, I just wanted to make people aware that it could potentially happen and if it does it might mean an incorrect bill, perhaps a big one. Yes, the supplier will probably refund the customer but only if the customer is aware. The clock might be out by only a few minutes but that could mean quite a lot for those of us with ToU tariffs.

MWT

Yes, I've had this problem with a smart meter.

Not as extreme as the quoted example but mine drifted by about 15 mins which caused a similar issue with the start of home battery charging being in the peak rate period instead of the low-rate.

The problem was fixed by asking my supplier to send a resync command via the DCC.

The clocks are normally kept accurate by reference to the gird frequency but you can get variations over time or faults as a result of power cuts.

Once a drift has occurred it will not get automatically fixed without external intervention so if you notice any oddities across the rate change boundaries the first place to check is the meter time. Do it at the meter, not the IHD.

Mine is currently about 5 seconds slow but that is not worth reporting.

QrizB

Has anyone had this type of problem?

We've had several power cuts since our smart meter was installed, some lasting for hours. I've not noticed any loss of clock synchronization, and we've been on a TOU tariff with a smart meter for four(?) years now.

I suspect it's a sign of a problem with the poster's meter, rather than a systemic issue.

SMs have are equipped with a battery or capacitor that maintains the meter’s clock in the event of a power failure so it should not happen unless the meter is faulty.

Agreed. I'm sure we can all recall examples of backup batteries for clocks failing, but that's a fault condition not normal operation.

As the quoted message in the opening post states, smart meter clocks can be corrected over-the-air once the supplier is aware.

(There's an argument to be made that smart meter clocks should automatically resynchronize whenever they're polled by the DCC, but there could be a good reason why this wasn't part of the spec.)

The Guardian reported on it 12 years ago.

That report seems to relate to traditional meters, which used a variety of clock technologies.

The original electromechanical time switches could definitely be affected by a power cut long enough to let the clockwork backup run down. Later digital meters had quartz clocks which would drift; some models were more prone than others, and all relied on backup batteries and could develop faults.

The most reliable were the RTS meters which were synchronised by long wave radio transmissions (which have recently been switched off).

Smart meters, reporting regularly and being capable of OTA updates, have the potential to be more reliable (from a clock perspective) than any of the traditional meters bar the RTS ones.

Edit to add: various forumites with E7 have previously reported on how their time switches used to drift. I think @dunstonh is/was one of them.

Reed_Richards

The display on my smart meter shows date, time, import reading and export reading in succession. So if the time was wrong it should be obvious.

Edit: I was not assuming that because it is easy for me it is easy for everybody else. Rather, I was posting to demonstrate that although finding the meter time is difficult on some meters, that is not always the case.

Bendo

Obvious if you look at it. Mines in the garage and since it's a smart meter, I've zero inclination to go and look at it.

MWT

https://forums.moneysavingexpert.com/discussion/comment/82073375#Comment_82073375

Not all are so helpful unfortunately, with some the time is buried deep in the menu system…

JKenH

My Landis Gyr smart meter is in the outside meter cupboard so I never look at it and wouldn’t notice if the time was wrong. Having said that I have just been to the meter box to have a look. The time is not displayed on the default screen but after a bit of googling I managed to find it and it was correct.