Why have I got some very high gas half hourly usage showing on MyOVO?

Userlevel 3

Anyone else see nonsense gas usage like this?


71 replies

Userlevel 3

I’m pleased to say that’s now  2 weeks without missing data or data errors. I did notice one day that the previous day’s half-hourly data wasn’t available until some hours later than usual, so I guess there is some amount of “if at first you don’t succeed, try and try again” in the way the data are being transferred.


Userlevel 7
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Hmm. I wasn’t too concerned at having the odd erroneous reading of 188250.978 kWh because the Billing Software sensible enough to not actually base a Statement on such an amount.

However, I’ve now discovered a new error. Have a look at my Gas Usage graph from Sunday 19jan20

So what’s happening here?

This is a very different class of error. Yes, it’s very high, but it could almost be credible.

I won’t know what the Billing software makes of this until the middle of February, when my next Statement is due.

There are other, even more believable erroneous errors. Here’s one from 2 days earlier on Fri 17th Jan

No, there wasn’t any sudden demand for gas at 3:30 am !

And no, the zero readings between 6-8am are also incorrect. My boiler was of course running during that time, as you’d expect in the middle of winter.

What’s alarming about this one is that it would be very difficult for software to filter out the errors if they had occurred the other way around. If there were 4 half-hour periods of zero-readings followed by a reading of 11.4 kWh, then it would seem quite reasonable.


What do you think @Amy_OVO ?

Can you bounce this to the relevant programmers’ team please?

I think they need to (re-)read what I posted here further up this Thread about the overall handling of erroneous data.

Userlevel 6

Hey @Transparent.


We’re raising this with the team to look into, I’ll let you know when we have an update!


Don’t worry too much about your statement, you won’t be billed from these graphs.



Newly installed smart meters last week, so I’m checking the numbers regularly to get a feel.  Currently have 7 day’s readings, my gas use shows 4 of the days as having huge peaks of usage - typically 188250.98kWh (“normal” currently 2-3kWh).  Up to yesterday these small duration “blips” didn’t seem to affect totals.  

Yesterday (12th) shows this peak lasting from 16:00 to 23:00 and the monthly/daily totals for that day  show a 40% increase in use.  What’s going on?

Userlevel 6

Hi @whitehouse,

Can you take some screenshots of this on your app and post them on here so we can have a look?



Here you go - starts with month then bottom/top of 12th, 11 etc … also included an “OK day” so you can see typical usage.


Where there is a “blip” the scale of the display changes so you can only see the big number - the other slots appear blank 


Userlevel 6

I’ve popped you post here, @whitehouse, we’re waiting on an update regarding this issue, we’ll keep you posted. 


Userlevel 7
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Thanks for joining in the discussion @whitehouse 

You are seeing the same error as @102530130 and I. So I think we’ve concluded that 188250.98kWh is effectively a “wrap around”. The Usage Software is programmed to expect only a positive number, but instead receives something that is marginally negative.

Let us know here if you see the other type of error, which I demonstrated above. That’s where the reading is very high, but could almost be credible.

This will need to get resolved before OVO can release a variable rate Time Of Use tariff.

For more information on the Smart Meters you’ve just had installed, have a look at this other Topic on SMETS2 Installation.

Hi all ….  mmmm sets as many questions as answers - I didn’t think the solar panels were  relevant at the time - but there seems to be some hints that they may be a factor.  I’d sort of realised that they were some sort of tech glitch - and until the 12th they didn’t seem to be making an impression - but as a total newb  I don’t have the detailed feel for my flavour of normal yet.  Then the 12th happened and the overall totals went up significantly and a bell started ringing  That I’d suddenly got some very plausable readings that were 40% higher … but at the moment my grasp of normal isn’t particularly tight.   

As things stand I’ve got solar panels (9 years) which I’m quite comfy with.

The central heating boiler was an old clockwork job, changed 12 months ago for a new fangled tech job.  so OVO have been on my case about standing orders not covering estimated use when estimates are going to be based on a boiler that’s no longer in service.

I’m retired and the heating is never altered - our routines are pretty constant too - so the only variable is weather.

Finally - I’ve just started driving an EV - so that’s another variable that will cause an increase but I have no grasp of yet.

That said - all the new factors are electrical and yet its the gas mainly which seems to “blip” - even when the sun don’t shine.

Because  I have solar - and because One of my jobs was statistical analyst for a large company - I’ve got 9 years of usage trends … unfortunately my usage has changed significantly in the last 12 months - so we’ll see just how much things have changed.

It’s going to be interesting to see where this goes.

Userlevel 7
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I was just about to sign-off for the night when your post arrived, @whitehouse . :slight_smile:

Solar PV should not be a problem. Assuming you’ve got a nice shiny new SMETS2 electricity meter, you will notice that it has separate data for power exported. Depending on what mater you’ve got, press the left/blue button to have a look through what it’s recording.

The bizarre 188250.98kWh we are seeing is for gas usage. 188250.98 is effectively another way of reporting zero, but with a minus sign in front of it!

The Communications Hub (on top of your electricity meter) has different interfaces to import readings from your gas and electricity meters. There is no possibility of electricity export from PV panels interfering with memory locations used for gas.


There’s lots of stuff on this Forum about EV charging, and the two chargers designed by OVO’s sister companies, Indra and Kaluza. Have a look at what we’re discussing and ask those EV questions on the EV Topics.

The V2G charger currently only operates with the Nissan Leaf.

The Smart charger is generic, but can’t export back to the Grid. It simply chooses the optimal time to recharge the batteries, avoiding the times of peak demand.


You don’t need to be technically correct on this Forum. We all manage to ask naive questions from time to time. :scream:

Userlevel 3


You are seeing the same error as @102530130 and I. So I think we’ve concluded that 188250.98kWh is effectively a “wrap around”. The Usage Software is programmed to expect only a positive number, but instead receives something that is marginally negative.


Well, we speculated along those lines, but @Tim_OVO  subsequently said:

“It seems as if when the issue occurs, instead of returning a null value or an N/A the fields populate the maximum available volume which (when used in the m3 to kWh calculation) generates this spike. Not ideal!”

which may be another way of saying the same thing, maybe not.

Transparent - thanks for the reassurance  

If this had happened 12 months ago I’d have been reasonably confident I knew my patch. but now I have far more questions than answers.  My old motor was a hybrid so I’m familiar with the cold weather dip etc - the new … erm - motor? wheels? are too new the reduced range mean I have to become a glass half empty type to avoid constant trickle charging (which is my instinct).   After reading far too many spec sheets I decided that for my usage getting a smart charger smart enough to interact with PV and  also be eligible for the £500 subsidy would cost me more (tyically an additional £1500ish over and above the £500 subsidy) than I could expect to recoup in 5 years - so I’ve funded a quite basic Rolec myself intending to use the nissan app to choose my charge times to fit in with my off peak schedule … or at least that’s the plan if the sun ever shines again ….!

My local authority is currently offering free fast charging ‘till oct 21 and incredibly one of them is opposite my usual parking spot in town (at the moment I have no competition for the plug) - so I top up regularly for free and my running costs are low.

Its a new meter but unfortunately it’s at floor level and the LCD polarisation means the reading angle requires me to lie face down which terrified the wife the other day I was like an upside down beached tortoise!  I intend buying a yoga mat, headtorch and reading glasses to have a good look at what the meter is capable of in more detail.  :nerd:


Userlevel 5

188250.98kWh  doesn't correspond to any binary number I can think of that might be a divide by zero or underflow.  Nor does its m^3 equivalent of 17079.897

I'm not on smart meters but many months ago my usage would display ridiculously high consumption figures in the usage graph , despite the monthly data in the table below being reasonable. It is mostly fixed now but going back a couple of years the graph does not agree with actual use. The erroneous data is now too low.

I just ignored the graphs for  a year or so. It doesn't make a good impression when apparently simple stuff is wildly incorrect.  ( I expect that to be an ever increasing experience and not just limited to OVO)

Userlevel 7
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Meters don’t record usage in kWh. 188250.98kWh is a figure derived from the volume of gas measured in m³ or ft³ multiplied by the calorific value.

If you want to spend a few hours doing equations, @NoPoke, then you can probably work out the maximum possible values that OVO’s programmers have allowed for each of those variables. :thinking:

Userlevel 5

That gas consumption is equivalent to 9.5 m^3/sec or 270km/sec in 22mm pipe.  Some 400x faster than Concorde!  

Userlevel 5

FWIW here is my best guess at what is going on.

The database is storing volume consumption figures in litres in a 24 bit unsigned integer.
There is an uncaught divide by zero producing a maximum value in this field 1677215

convert to m^3 => 1677.215
apply standard volume correction figure of 1.02264    =>  17157.0511476
divide by 3.6 (convert from MJ to kWh) => 4765.847541

Then apply a fixed?? calorific value of 39.5 => 188250.9778695 kWh 
Which rounds to the 188250.98 displayed figure.

I did look up UK daily calorific values and 39.5 was a valid value for some of the highlands and islands, but not for the majority of  the UK. So I wonder if the graph uses a fixed compromise value of 39.5 rather than actual daily figures for the region. 

Userlevel 7
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OK… so two bits of feedback:

Firstly for @whitehouse - when looking at payback times for EV chargers and other energy-saving technologies, please bear in mind that we’re moving towards a domestic energy strategy called Demand Side Response.

This means customers will increasingly be offered a Time Of Use tariff (ToU) with variable pricing based on half-hour time-blocks.

If you opt for such a tariff, you will be able to have more control over when you charge your EV and use other high-energy household appliances. This will affect your payback period.

There’s other Topics on this Forum where we’ve discussed Demand Side Response, and you should see more about ToU tariffs over the next few months.


Secondly, on the subject of the Calorific Value for @NoPoke’s calculations; I’ve just received an excellent response from my GDN, Wales & West Utilities.

I’ve been given a number of documents to read online, and introduced to the concept of Wobbe Numbers. So I’ll have to do some background research into all this.

However, WWU included the following graph showing Calorific Values in my Region (SouthWest) over the past two years.



This should enable us to make a better guess as to the range of CVs which OVO’s programming team may have allowed for.

CVs will be gradually falling in the future as new legislation allows to more bio-methane and hydrogen in the mix.

I’ll return to this again once I’ve done my homework!

OK… so two bits of feedback:

Firstly for @whitehouse - when looking at payback times for EV chargers and other energy-saving technologies, please bear in mind that we’re moving towards a domestic energy strategy called Demand Side Response.


DSR sounds interesting.  As a simple soul I simply intend to charge while the sun is over the  yardarm and my panels are producing magic pixies for the picking - for me this will be mid afternoon may - october.

When I first ran the numbers I factored in a charger with all the bells and whistles that could talk to solar, ev and my phone - as I said it soon became apparent that the registered installers required by DVLA in order to be eligible  for the £500 subsidy saw that figure as their starting cost point. Also seeing that an EV has an initial purchase subsidy too, they’ve also decided that they should be entitled to a “fair” chunk of that too.  When any cash-cow is crossed with a golden goose - the only certainty is the prices will inflate to quite silly numbers and £2000 isn’t rare for a very basic install.  So that subsidy isn’t quite the boon it looks to be 

The T&Cs say they will provide your external wall mounted charger with the shortest surface fixed cables they can..  I wanted mine INSIDE the garage which is where the car usually sleeps.  It seems obvious that if the crimms  are eager to cut down anything made of copper however high the voltage it carries - as EVs become more popular - so will the easy money option to “harvest” those domestic wall chargers, external cables and flex as the car sits conveniently (and visibly) on the driveway tethered to a big chunky length of copper over night!  

The car has an inbuilt timer and there is a nissan app - so with a little thought its easy enough to set that to fire up at whatever time is required without getting wet.

It took a day to dig a trench and lay duct - I’ve upgraded the garage, added a wireless access point that covers the garage and garden too and it’s all under lock and key.

Userlevel 5

Not a fan of hydrogen.  Has a very wide flammability range (much wider than methane) and requires very little energy to ignite (an order of magnitude lower than methane).  Hydrogen is also four times smaller than methane so much more likely to leak from the system.

Userlevel 7
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@NoPoke- whatever we think of Hydrogen is unlikely to affect the plans to increase its presence in the mix. Unlike Methane, it is a zero-carbon fuel.


Moreover, using spare renewable electricity, which would otherwise be discarded, to create hydrogen from water makes economic and environmental sense. It costs very little to send gas through the grid-pipeline hundreds of miles to where it can be used.

Contrarywise upgrading the electricity National Grid to accept that excess renewable generation would cost £billions, and about 15% more energy would be wasted in grid losses.

See The Engineer article about Scottish Hydrogen Storage Project, Oct 2019.

Userlevel 5

Our gas grid is constrained too.  https://www.nationalgridgas.com/data-and-operations/constraint-management

Adding Hydrogen to the methane reduces the calorific value and will thus increase the volume demand on the pipes.  The exact opposite of what you would wish as this acts to decrease capacity.

Userlevel 7
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Erm @NoPoke - the Scottish project I referred to is for Hydrogen Storage.

The team are to investigate the viability of storing hydrogen when renewable energy is in abundance, then use it when there is a deficit. Thus it evens out the fluctuations in renewable generation.

Most of these gas-generation strategies are intended for use within the Distribution Grid rather than sending through National Grid pipelines.

Userlevel 7
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For the sake of comparisons: the pseudo-minimum Calorific Value of mains gas is 37MJ. That’s what would be used to calculate our bills if there was a problem with measuring the actual CV.

The equivalent CV of Hydrogen is 12MJ.

The amount of hydrogen permitted within the mix is fixed by legislation in the Thermal Energy Regulations.

It is absolutely impossible to get through on the telephone at the moment. There are 4 days in April where my gas usage went up 15 times and electric 8 times a day. There are two of us in the household which is a two bedroom flat so I’m sure this is incorrect.

It went back to normal on the fifth day.


Any suggestions

Userlevel 7

Hi @Wardlin 


Sorry to hear about your troubles getting hold of Support on the phone. Our current wait time is under 5 minutes, using our main contact number: 0330 303 5063. 


Can you have a look at this topic (I’ve moved your comment onto it) and let me know if this is a similar issue? If not, some screenshots would be great!