Different readings from Smart Meter, App and Web Site (Scottish Power)?

RSTime

We have recently had our Smart Meter reactivated (after being down for several months). The data produced from the IHD, app and web site are all different 🤔

For the 9th November the following data was reported:

IHD (Smart Meter)

46.38kWh

£6.94

Scottish Power App

46.94kWh

£8.42

Scottish Power Web Site

49.83kWh

£9.57

Any idea what is going on here, clearly the Smart Meters are giving me very different charges to the app and web site. 

Best wishes

Tony

[Deleted User]

Are you talking gas or electricity? 

The most likely reason that I can think of is the slot data pull time. Each smart meter has 48 half hour slots per day. When I had this issue with the BRIGHT app it was because they took the midnight reading at at the start of the midnight slot but the supplier took it at the end of the midnight slot.

With Octopus it also gets slightly more complicated as the previous day’s usage on the following day is 30 minutes out until the following day’s data is pulled. This is why when my billing time/date is midnight of the 27th, I don’t get my bill until the morning of the 29th.

Smart meters are not in permanent contact with the suppliers whereas IHDs are in constant contact with the HAN. The supplier usually ‘calls’ the meter in the early hours of the morning and it issues a ‘pull’ command for data. The meter returns index readings for 4 registers with 30 minute usage data in XML files.

In sum, you have nothing to worry about. IHDs and apps are advisory: what matters is your actual bill.

RSTime

This is the total energy usage of gas and electricity, see attachments below.

So which charge is correct, the IHD is showing £6.94 usage for 9th November, a big difference from the £9.57 on the web site?

MWT

RSTime said:

This is the total energy usage of gas and electricity, see attachments below.

So which charge is correct, the IHD is showing £6.94 usage for 9th November, a big difference from the £9.57 on the web site?

Check the rates that are shown on your IHD, it will be in the menu somewhere, and you will probably find that your supplier has not updated the tariff recently so that is where the large cost difference originates.

Similarly when looking at the gas kWh figures, the IHD uses a fixed conversion factor to get from m3 which the meter records, into kWh, whereas the supplier must use the actual calorific value when calculating your bill, so there will always be a small difference there.

RSTime

MWT said:

RSTime said:

This is the total energy usage of gas and electricity, see attachments below.

So which charge is correct, the IHD is showing £6.94 usage for 9th November, a big difference from the £9.57 on the web site?

Check the rates that are shown on your IHD, it will be in the menu somewhere, and you will probably find that your supplier has not updated the tariff recently so that is where the large cost difference originates.

Similarly when looking at the gas kWh figures, the IHD uses a fixed conversion factor to get from m3 which the meter records, into kWh, whereas the supplier must use the actual calorific value when calculating your bill, so there will always be a small difference there.

Indeed, the incorrect rates were in the IHD. Does the IHD not update automatically with the current rate? Is this a common issue, if so there will be consumers who are oblivious to their real energy costs and will only become aware when their bill arrives...

MWT

RSTime said:

MWT said:

RSTime said:

This is the total energy usage of gas and electricity, see attachments below.

So which charge is correct, the IHD is showing £6.94 usage for 9th November, a big difference from the £9.57 on the web site?

Check the rates that are shown on your IHD, it will be in the menu somewhere, and you will probably find that your supplier has not updated the tariff recently so that is where the large cost difference originates.

Similarly when looking at the gas kWh figures, the IHD uses a fixed conversion factor to get from m3 which the meter records, into kWh, whereas the supplier must use the actual calorific value when calculating your bill, so there will always be a small difference there.

Indeed, the incorrect rates were in the IHD. Does the IHD not update automatically with the current rate? Is this a common issue, if so there will be consumers who are oblivious to their real energy costs and will only become aware when their bill arrives...

There is no way for the IHD to automatically do anything, it has to wait for a message to be send out from the supplier, via the DCC, containing the updated tariff information.

Some suppliers are reasonably good at doing that, others are very slow and some are close to doing nothing at all.

Personally I never look at the cost information on the IHD, I find the kWh information more useful.

Raxiel

Another factor that leads to the IHD only being an approximation for gas, is that the meter measures in volume, but you pay for the energy, and the amount of energy (kWh) in a given volume (m³ or hcf) can vary.

When the bill is produced, the supplier uses an Offgem formula with sampling data from the network operator for that specific billing period. The IHD doesn't have that information (nor does the meter itself if it offers a kWh read as well as volume) so they just use a fixed value. Typically 11.2 to convert m³ to kWh.

The true, billed value doesn't normally differ by much, but it can add up over time.

RSTime

I am not an expert in the area but from a distance the whole system appears to be overly complicated and frankly a mess. Depending on your supplier your IHD may or may not be giving you accurate data (and customers may be totally oblivious). If the IHD received actual data from the supplier would that not be a sensible solution (much the same way that the app works), or am I missing something?

Sorry to be grumpy but our Smart meter has not worked for several months and I have had to spend weeks troubleshooting with the supplier, including several visits from Siemens engineers...

Raxiel

What's supposed to happen is the supplier sends the information to the DCC network, and then the DCC sends that to the meter, finally the meter updates the IHD.

Apparently suppliers have to pay to send stuff over the DCC, so I guess sometimes they just don't bother?

Octopus have been fairly good at keeping mine up to date recently, within a couple of weeks of a change, in the past it took longer.

That said, they still only show the actual published tariff rates, not the additional discount to bring it down to the EPG, that doesn't get deducted until the bill.

wild666

I don't have a IHD anymore but the readings from the APP and website differ by 0.008 kWh, over a year it's 2.92 kWh or about 65p but over the last week or so they have given the same exact reading on both.