Unexplained half-hourly usage pattern

My apologies, but another observation from me: The SWALEC estimate of annual usage of 7325 kWh from 2021 is on the high side, but I would say perfectly within the realms of possibility.  Ofgem reckon that a high user of electricity would, typically, use 6700 kWh per year. (I do know that your mother lives alone and their estimate is based on a house with 4+ bedrooms with 4 to 5 occupants). However, the OVO estimate of 13816 kWh for a year is close to twice what SWALEC estimated and way beyond what Ofgem regard as a high domestic user. You say that nothing your mother does now is different from what she did in 2021. What I am going to suggest now will take some time to actually complete, but it may help to work out what is using such a high amount of electricity every day. Looking at the figures you have supplied for 2025-2026, the usage works out at just under 41 kWh per day. If we forget for a moment the original reason for your post (the strange recorded usage) and assume that the usage is correct, something has been using that energy. Back when energy prices last went crazy, we bought a couple of energy monitors like this to see what things in our home used the most electricity.

It was very useful in identifying the things that were more or less expensive than we expected. It may be worth looking at things like your mother’s fridge freezer, the heaters she uses, when necessary and other things that she uses a few times a day. We did this for our kettle, fridge freezers, our oven, TVs and tumble dryer. As a result, we changed our habits: we bought a water boiler that only heats enough water each time for one cup (only one of us drinks tea and coffee) to replace the kettle, we bought an air fryer (misnamed appliance as it is a small oven in reality) which means we rarely use the main electric oven and we now, as often as possible, dry things on the line in the garden and almost never use the tumble dryer. In 2022 we used 3649 kWh of electricity over the year, in 2025, we used 2837 kWh of electricity. We have gas for heating and hot water. This may help to see if your mother’s bills can be brought down even if we have not yet got to the root of the strange display of usage. 

One final thing: I have sight problems so access my OVO account, mostly, on my PC rather than on my phone. It may be worth looking at your account there to see if the display there is any different to the app.

​@Ben_OVO is there any plan that is current that would show zero usage at night between these hours. When I can guarantee there are lights on, TV on and fan heater ??

I appreciate all the input but I would like to understand if anyone knows of any scenarios that would see 0 use for those hours ??

All readings are “Smart”

Photos. 
 

Two fan heaters Mum has running 

Lights, Small TV, Fridge/Freezer and Kettle are the other devices.  She does have one of those heat on demand Shower Units as well. 
 

Photos. 
 

Mums Fuse board inside the house

Smart meter

Hey ​@rogerp64 

Thanks for sharing those photos, those are super helpful, though I definitely still have a few more questions about your mum’s set up.

I do wonder how long she runs both heaters? Though doesn’t account for the timings not matching up/missing from the AM where you say she’s up and active.

There definitely isn’t such a thing, unless there simply was no usage during that time which you’ve mentioned mum is a night owl so that sounds odd if it’s not showing usage during the expected times. It was already mentioned and shared previously but it might be worth seeing if mum can complete what’s known as a kettle test. 

• Take a reading from the meter you think is yours (take a photo of the meter clearly showing the Meter Serial Number and reading)
• Use as much electricity as possible for 15 mins eg boil your kettle three or four times, turn on the TV and all appliances and lights, use your hairdryer etc
• Check if your meter’s clocked some electricity usage (boiling a kettle once normally uses 1kwh of electricity). Take a second photo of the reading.
• If your meter hasn’t clocked any electricity use, then the usage may have been clocked on a neighboring meter

This would help make sure the meter in question is definitely the meter clocking the energy to the account.  I would also suggest reaching out to the Support Team to cross check the meter details are correct. This way they can also double check, request a meter reading to test the meter connectivity as well as any other things they can check that we can’t here at the Forum.

It’s tricky to tell but we appreciate your photos and information and hopefully we can get to the bottom of things for you and your mum.

I wonder if ​@Peter E might have any insights from your electrical expertise? 

Photos. 
 

Two fan heaters Mum has running 

Lights, Small TV, Fridge/Freezer and Kettle are the other devices.  She does have one of those heat on demand Shower Units as well. 
 

 

I hope that these heaters have thermostat controls. Many such heaters are capable of using 3kW of electricity every hour they are in use. (This is just an observation as I know that usage and cost are not your primary concerns). I remember living in a couple of properties where this kind of heater was my source of heating and how comforting the instant heat was but how disappointing it was that I quickly became cold once they were switched off.

thank you ​@Abby_OVO , 

The MSN on the Meter matches the MSN in the Portal.

I’d have to arrange for someone to do the kettle test.. Mum would not be able to do that and I’m very distant from her..  so photos, etc are coming from carers that drop in.

As you say there zero usage is still the big unexplained element..  the Fridge/Freezer is on 24*7, TV, heaters and lights are on and iPad is charging always after midnight until at least 4 or 5:00am.

​@Bendog - I think they do have thermostats, but Mum has them cranked to the max… so doubt they ever cut out….  However, she is never downstairs using the heaters in the early morning.. and most certainly wouldn’t be turning them on at 07:00 on the dot…

(I’m secretly happy that there is no clear and obvious answer, but I can bet that when the answer is found it’ll be instantly clear and obvious !!)

​@Abby_OVO and others. I have been following this but I've not been able to come to any clear conclusion mainly due to the lack of information so I'm going to try a different tack to see if the usage is at least explicable.

I have an elderly mum who is now 96 and she has the house very hot. Taking my house as maybe being something to your mum’s, 41kWh a day will maintain a temperature differential between the outside and inside of about 9C. The current average temperature at the moment on the south coast (I don't know where you are but it is probably cooler if you are significantly further north) is about 12C giving me an internal temperature of 21C. That is not an unusual temperature for someone who is elderly and perhaps not very mobile.

41kW a day is a steady 1.7kW. I noticed that it is just possible to see that the fan heater is set to 1kW but I don't know what the thermostat is set to. After all that I can't say that 41kWh a day is what you are using but it seems possible, given the circumstances, that it us possible for that to happen.

I'm going to go back and re-read everything I've said and see if what I've said is still feasible. If you've any comments please let me know. This is a complete punt in the dark 

I think ​@Nukecad is right about estimated readings and I've been fooled by by the graph before. My one showing usage when we had a long power cut.

Peter

A note. It's only a 2kW heater. 3kW heaters were banned from being sold some time ago as they were causing sockets to burn out. Although they are called 13A sockets and the plug has a nominally rated 13A fuse (they will take a lot more) the plug/socket is only rated for 10A continuous current.

13,800 kWh a year is an average of 37.8kWh a day just to refine the figure a bit although I’ve now thought that would be a year average figure. In my house with a room temperature of 19C my heating season energy is about 10,000kWh with my non heating season energy to be added to that.

Peter