How are usage figures generated when I export to the grid?

  • 17 July 2022
  • 6 replies

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After 2.5 yrs with OVO, the new App and website has allowed me to see the usage figures for my electricity usage for the first time… (it was blank and no one wanted or was able to fix it!).

I have a 1.2kW PV installation and am also part of the V2G project, so my Nissan Leaf export about 10-15 kWh per day back to the grid.

My IHD therefore often shows a negative figure because we are not using all the PV or the car is exporting (generally around 3kW per hour when operational).

Looking at my usage figures, there are no negative values and almost no values of zero… so I surmise that the meter must log into the export data list when the power is negative and restarts logging when it its positive... This means that even on a sunny day, if the usage in the house tops the 1kW we are producing for 1 second, we will get a positive reading on the usage graph… To get a zero reading, we will need to supply a negative value for 1800 seconds of the each 30 minute window.

This raises some interesting questions about the export figures because without them the usage figures are meaningless, as they do not actually show what I have used… it would be very interesting to see them and start to analyse the real usage including what the car is doing and what the PV is doing…. is there any way to access this data? Clearly it must be available, because OVO use it to pay me for the power they take from the car!

6 replies

Userlevel 7

Hi @NeilG,


Great to hear your usage graphs are now able to show your imported energy. Some really valid questions to ask about collating this with your exported energy. I’m wondering whether your fellow energy exporters might have some good advice to offer on the way they track this data.


@ArundaleP  @sylm_2000@PeterR1947@EverythingNeedsAUserName@hydrosam@Jequinlan  - I know you all have solar panels and some of you also export energy using V2G. What are your go to methods of monitoring your energy exports. Any third-party apps which you’d recommend?

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For me, Usage data is always positive or zero in the app. I have solar PV only. 

On my ancient IHD it shows how much negative at the time. 

OVO only knows how much I've generated and exported because I report it quarterly. Presumably the internal use is the difference between the two. 

I have read that recent smart meters also record data on exported kW, but I don't know how they can tell us what we've used in the house without linked smart generation system meters. 

Userlevel 7

Just raised this one to the Smart Home team, @NeilG.


They mention that whilst your export data doesn’t appear on your OVO Energy App, it should be viewable on the Kaluza V2G app. Have you been able to access this?

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Thanks Jess, I too have been in touch with Smart Home Team…. and Ofgem as regulators and Capita as controllers of the DCC. Yes, I do use the Kaluza App, but that is only part of the story… The App does show what the collar has measured going up and down the cable to the charger, but apparently, this is not accurate and does not show the PV export element or deduct what has been consumed locally. The billing is done using the export data in the Smart meter and includes PV hence the lower rate paid for those with PV. It obviously, does not include the power used in the house either!

Basically, in the first instance, I am concerned about the transparency of the billing process for V2G… we get no statements, just a single line showing the money each month with no idea how the figure was generated... No start reading, no end reading, no difference value or price and calculation. Without export data, we have no idea what we are being paid for, especially as it is further complicated by both PV and household retention. It is even more complicated, because V2G does not run to the same billing period either, so no extrapolations can be created in any shape or form!

In an attempt to get information, this led me to look at the usage data pages provided on the website… the problem is IT IS NOT USAGE DATA! It is just 30min statements of what goes into your bill, so for anyone with micro generation, V2G or anything else which might create an export, it is totally misleading. Usage is actually import + generation - export. I appreciate that the site cannot show generation, but most PV systems and Kaluza can (as the Smart Homes people point out). But as can be seen, it is impossible to work out consumption (usage), without access to export data. Equally, it is impossible to extrapolate export data without accurate usage data!

Let me provide an example of how wrong the data is…. today it is hot and sunny, so I am generating 1kW of PV. At 15.30 the car may well start to top up the grid and export another 3kW. If I look at my usage figures on the web, it might show 0kW for the 30min segment. In reality, I may have boiled the kettle, been using the washing machine and had an array other home appliances running, but will have no way to see this reflected in the data which appears to mimic the instantaneous data shown on the IHD…. but doesn’t. In reality, I may have used 0kWh, but equally, I may have used the whole lot or anywhere in between. I have no way of knowing… It is an error which is infinitely large!

I am therefore very concerned that the website is wholly misleading for anyone involved with exporting in any way, shape or form, especially as it is used to promote information about how to  reduce consumption, carbon footprints, costs, etc..

My feeling is that the website needs to show both import and export figures if it is going to pedal advice about how to improve your efficiency or energy usage. Providing the wrong information is worse than no information at all! At least with no information, you know where you stand… with wrong information, you probably believe and rely on what are being told! 

In reality, it is easy to fix... Show the aggregate figures for import/export (not ideal for billing, but ideal for efficiency work and usage) or even better, show both (as bars above/below the axis-line with a line graph to show the aggregate) and explain the above axis data goes to the bill and the below access is what is exported.

The next stage would be to provide information for exporters as to how to work out their actual usage and to provide a (CSV?) export of the graphs data, along a similar export from Kaluza for V2G (to save having to scavenge the data manually bar by bar from the Apps graphs)…

Food for thought!

Userlevel 7

Thanks for sharing this, @NeilG


Energy exporters would benefit from this visibility. Our product teams can be made aware of the idea, and its popularity, by having a feature request ‘Idea’ posted. 


Would you be able to post a summary of this usage feature improvement as an idea? I’ll vote on it...

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Thanks Tim….  Will do!