[Mystery] £400-600 monthly home electricity bill with Octopus

[Minato]

@Minato something is seriously wrong somewhere, you're probably powering next door! Start a thread, post a link here.

Afternoon chaps,

While having a moan in the solar panel thread about my electricity usage at home, it turns out something might be wrong somewhere. Apparently a baseline usage of ~1.5kW on the Octopus Home Display is unusually high. Encouraged by @b0rn2sk8, @200sols, @alphaomega16, and @Ron-ski, I'm posting this thread to try and figure out if my neighbour is siphoning my power or something.

I'm on the Octopus Tracker tarriff, and have been with them since April 2024. I live in a fairly large detached house, but with I think normal appliances. A couple of fridge/freezers, washer, dryer, dishwasher etc. I have an air source heat pump for the pool, but it's been turned off for >1 year as it's not being used. Central heating is gas. No electric radiators or anything like that. Backup immersion heaters that are in the water tanks (close to brand new, had a new boiler room fitted <12 months ago so no issue with old equipment) are turned OFF. I have a couple of electric cars that get charged ~twice a month each. Each charge costs around £12-13 at current prices.

I've exported my data yesterday and done some analysis to try and figure out what's going on.

For 1st April 2024 to Present:

• Average Daily Usage (kWh): 65.95 kWh
• Average Daily Cost (£): £12.69
• Peak Usage Day: June 14, 2024, with 145.19 kWh
• Average Daily Usage (Excluding Car Charging Days, kWh): 55.27 kWh

This shows my daily usage from April to Present, with the car charging days (evenings/nights with consistent blocks of >4kW usage for several hours) highlight. To make things clearer, here's the car charging days excluded.

And finally, here's our average usage per hour over the entire time period

Spoiler: Chart

You'll note that in first two charts, our average usage seems to have increased since October. No idea why. But the data supports this:

For 1st October 2024 to Present:

• Average Daily Usage (kWh): 74.68 kWh
• Average Daily Cost (£): £14.92
• Peak Usage Day: November 9, 2024, with 144.68 kWh
• Lowest Usage Day: November 22, 2024, with 44.11 kWh

Troubleshooting

Since this was flagged up to me as abnormal, I've been paying close attention to the data. According to the Octopus Home Display thing, in the last few weeks I've had several >£20 days, with a couple of >£30 days. This is getting really pricey and I want to figure out if there's anything I can do to fix this, since even solar panels wont help me generate 100kW a day unless I install a solar farm in the garden I think.

My display shows a consistent baseline of around 1.2kW usage at all times. That's currently costing around 30p/hr. Last night I did some investigation, here's the baseline usage:

This is with most of the family asleep, a couple of devices like a laptop on charge, and a few lights on in the house (all LEDs). All other devices like desktop PCs, TVs etc were on standby. No dishwasher/washing machine/tumble dryer (condenser type) in use.

So I went to my circuit board things, and flipped every single switch down one at a time looking for culprits:

• I went to the basement first, turned off all the circuit breakers for the water circulation pumps, boiler, pressure pumps etc. Hardly any difference.
• Turned off the power to the car charger (not in use), no difference.
• Turned off power to outside lights and floodlights, no difference.
• Turned off rooms and parts of the house via the circuit board one at a time. Not many rooms made much difference, turning off the kitchen with the fridges and freezers etc dropped things by a bit.

By the time every single circuit board switch in the property was off, and the house was effectively in total darkness, this was what the display showed:

So that's left me scratching my head. Why am I still using 0.66kW of power at that time? £0.16/hr doesn't seem like that big of a deal since it's just under £4/day, but when a 'good' day is a £12 spend and a bad day is £20+, I'd quite like to get that £4 down. Secondly, the general baseline usage of the house as above with things on standby and no big appliances in use is around 0.5kW (~£0.09/hr) which seems ok to me?

Advice, suggestions, thoughts (and prayers) would be appreciated.

Cheers

 

[Minato]

Faulty meter?

A ghost load of that much can only be an oven, an EV, an immersion heater etc?

If you're saying you've isolated all of those things then it's either meter or yes, someone pinching your juice.

However all breakers off other than incoming should confirm if it's on your side or meter side.

Edit; do you any old lights in the attic or something? Or a sump pump?

Thanks for the reply.
Meter was installed by Octopus not too long ago, not sure how to check if it's faulty as it seems to report data ok.

At the time of testing last night, ovens definitely would have been disconnected when I turned the breakers for the kitchens off, no EVs plugged in (and I turned off the Zappi charger via it's breaker also), immersion heaters were turned off at the switches in the tanks, and also breakers turned off in the same board.

A couple of old bulbs in the attic I think, which I didn't physically go and double check were isolated, but with all the breakers in the house down I can't imagine how would be powered otherwise. No sump pump.

 

[Minato]

How's the smart meter display running if every circuit breaker is off though?

lol exactly what happened when I cleverly turned off all the breakers and discovered the meter was off too /facepalm.

I isolated one room, worked out how much that decrease the wattage by, then put the meter in that room and turned off everything except that room. The room remaining on was a handful of watts only, not even £0.01/hr.

What happens when you switch the fuse box off?

If you mean my circuit breaker box things then as in my post, I'm left with ~660W being used with all switches down.

 

[Minato]

Presumably his smart meter measuring device turns off lol.

Op - anyway to power the smart meter display and turn off every breaker? Friendly neighbor? Inverter/car cig lighter?

What I did was have everything on as in the original pic so 1.11kW.
Then turn off the breaker for a single small room, dropped to around 1.09kW or something, so a negligible drop. Then I put the small room breaker back on, put the smart meter display in that room, and then turned off every other breaker for every other room/area/supply in the property one at a time and monitored the display. End result was that 661W pic.

 

[Minato]

Can you turn off absolutey every breaker apart from the room you isolated at 20w? I.e. the small room?

That's what I did, apologies if I wasn't explaining it clearly.

Small 20W room breaker up.
Every other room breaker (kitchens, bedrooms, living rooms, etc) down.
All swimming pool circuit breakers down (were already all down anyway, includes garage, shed, outdoor lighting etc).
All basement circuit breakers (boilers/pumps/zappi car charger/water tanks etc) down.

The end result of doing exactly that is the 661W pic.

 

[Minato]

Neighbours stealing leccy was tongue in cheek, they're fairly well off so I don't think they'd need to steal £4/day of electricity.

Loads of replies - thank you - but unless I'm missing something I've done a fairly exhaustive test of all the circuit breakers in the property turned off resulting in that 661W figure.

Even my actual baseline with generic things like TVs and desktops on, and some lights on (ie day to day baseline), I'm around 1.2kW so ~£0.30/hr. That should result in a daily use of 28.8kW. But my average usage on non car charging days is around 60-70kW. That's what I'm trying to work out, is ~30-40kW of daily usage normal?

Can you see the usage per 30 minutes on a graph against time?

Got power to sheds or garage?

There is power to shed and garage, but circuit breakers to both turned off in my testing last night.

 

[Minato]

Op do you have teenagers who are inexplicably wealthy? Two phones? Lots of cookie deliveries?

Nobody in the house is growing anything they shouldn't.

Does your IHD have a battery? if so you can unplug it and it still works for awhile.

Once you turn off all the breakers, if your meter is still recording 600w, you will be able to see this clearly on the meter itself.

The meter should be recording 0.1kwh every 10 minutes.

Next to the meter there should be an isolation switch for the whole installation. Turn this off, if the meter is still recording power usage, it’s broken.

What EV charger do you have and does it have a CT clamp? Can you read what this is recording and does it agree with your smart meter? If it doesn’t agree, it’s probably broken.

IHD doesn't, it needs to be plugged into a wall socket.

I will go and have a look at the physical Octopus Smart Meter itself to see if it gives me any information tonight.

EV Charger is a Zappi, I isolated this from the circuit breaker last night and it didn't drop the power usage on the IHD so don't think it's that.

 

[Minato]

Ok so here's a potentially interesting update following your suggestions @dlockers and @b0rn2sk8 especially.

I had another look at the Zappi charger. Turns out as you say, it's somehow connected to the mains and it displays the current power draw of the property, and seems to mirror my IHD pretty accurately. Which means I don't need to isolate circuits inside the house, I can do it from the mains boards in the basement next to where my smart meter is.

These are the mains circuit breakers that supply everything in the property. They're right next to my smart meter. I had a look at the meter, it shows my usage in kWh but that would mean having to turn everything off and wait an hour to see if it goes up by 1kW which isn't practical.

So I did the next best thing, I found the small breaker that supplies the Zappi and the Zappi only, left that on, and turned every other breaker off from the mains for the entire property.

Lo and Behold, the Zappi displayed 0.0kW for the first time.

Turning breakers on one at a time, starting with the far left on the picture above, the Zappi went to 0.4kW. The second one then turned most things in the house back on it seems, as Zappi went back to 1.1kW which is my standard baseline where it then remained.

So I guess that rules out a fault with the smart meter since it went to 0.0kW? And it means there's something dodgy on the property itself?

 

[Minato]

Did you not do the individual breakers in your consumer unit before?

So I've got these breakers in the basement next to the smart meter.
I've got 2 sets of breakers in the main part of the house inside that supply all the rooms.
I've got a breaker in the pool room, and a breaker in the garage.

The latter 4 sets of breakers is what I turned off last night, thinking that covered everything inside the house and property. But clearly that resulted in that ~660W still going. Doing it from the breakers next to the meter got me to 0.0kW. I'm not sure why there's a discrepancy there.

 

[Minato]

Sparky won't do anything you can't do. 400w on one breaker....start turning off everything to get it to zero. Rinse repeat for all the other breakers.

But those two main breakers are just a single switches, and I don't know exactly what it supplies since it's down in the basement.
The cabling is a bit confusing, I can't make head or tails of what goes where.

 

[Minato]

Any of the above.

Is none of it labeled?

It’s basically process of elimination I’m afraid. Working though it all circuit by circuit, mapping out what is going where and powering what. Labelling it all up and it will make much more sense.

Unfortunately not! Will try and figure it out.

 

[Minato]

All this for the sake of ~400-600W which is like £0.12/hr.

Meanwhile others in the household are cooking atm, and with an oven, an air fryer, and a diswasher running, we're currently using 7kW at a cost of like £1.80/hr. I think this is the type of stuff that really gets me to the 60-70kW daily usage rather than whatever this small leak is.

 

[Minato]

Did you read the thread? Their total baseload is 1.2kw 24/7/365 of which 50% appears to be unaccounted for. That is nearly 30kwh a day before any appliance like an oven is switched on.

I'm the OP mate haha

I just meant the hunting for the unaccounted for 'unknown baseline' is for the 400-600W I was able to eliminate today. When all the internal breakers were off, that dropped it from 1.1kW to 660W as in the first post. So basically all our stuff that's plugged in like TVs on standby, kitchen appliances like fridges/freezers, pumps in the boiler room, etc is using ~400-500W which seems like a normal number?

So 24hrs of say that 600W is 14.4kwh which yes is a good bit, but still a fraction of a 60kwh day (low end) or a 120kwh day (high end if a car is charged).

 

[Minato]

It isn't too mad to be fair -- I am sitting at ~400w with PC, Server, Router/Switches, CCTV, monitor, internal baby cams, fridge/freezer and chest freezer. Your average daily cost just seems mad though.

Are you on a proper tariff for your EVs? Octopus Intelligent or EON Drive or w/e it is?

Right so that's reassuring. A list of electric appliances off the top of my head:

Spoiler: List of everything plugged

• Main oven electric
• Fridge x2
• Freezer x3
• Dishwasher x2
• Air Fryers x3
• Chopper
• Blender
• Microwave x2
• Underfloor heating upstairs bathroom - electric, turned off
• Exhaust fans in bathrooms
• Pumps in boiler room x2 large, x3 small
• Circulating manifolds for water underfloor heating x3 small
• Hair Dryers
• Washing Machine x1
• Dryer x1
• Iron x1
• Cooker and Hob
• Area lighting outside
• Flood lighting
• Desktop computers x3
• Drinks fridge
• Room lights, mostly all LEDs
• Synology DS920 NAS
• Mesh Wifi Routers, ASUS x4
• Ring Elite Doorbell, wired
• 2x small 8 port switches
• CCTV
• TVs x4 (48" OLED, 100" Hisense, 50" Samsung, 75" Sony)
• Samsung Soundbar and 2x Rear Speakers
• Brother colour laser printer
• Zappi charger
• 4x Fujitsu AC units.

So even when none of that is in 'use', just the draw alone being even 500,600,700 or even 800W seems ok. That would be 19.2kW a day and cost a fiver.

It's how we get from there to a 60kW average day before any car charging that is costing me significantly.

Re Tarriff: no, we're on Octopus Tracker because it's been much cheaper than Eco 7 over the course of the year.

We used to have to do all of our expensive stuff like washing/dryers/dishwashers between 23:30 and 05:00 to save money since the tarriff was like 7p/kwh at night. But it was a bit exhausting and having the same price for all hours of the day is quite nice. We were saving a lot vs the standard cap price over the course of the year, seems only recently the prices have sort of equalised.

The EVs don't bother me so much as considering a tank of petrol is like £100 for that size car, £12 a charge is fine in comparison. And as you've seen from my charts in the OP, even when I exclude the car charging days the average daily use is still very high.

 

[Minato]

Just back on the topic of the unaccounted for 400-600W baseline - I just remembered we've got 4x Fujitsu AC units installed last year as a multi split system. There's 2 external units, 4 internal wall units. Those are basically air source heat pumps but in reverse right? I've not used them at all since it's winter, more so in preparation for hotter summers etc. The external units are powered via 1x 20 Amp and 1x 32 Amp connections, and then those supply power to the internal units (when turned on - which they aren't). Would those external units still be drawing power even if the AC isn't in use?

 

[Minato]

I assume you don't already have a solar and battery setup? not looked at why you posted in the solar thread - there have been instances before where the solar + battery setup is feeding into the grid with the meter advancing the amount incorrectly rather than it being offset.

I do not, I looked at it to see how much people were generating and if maybe I should invest in a system to cut my bills down. But given that in winter people are generating like 1-3kW a day it wouldn't really touch even my 'low use' (60kW) days.

 

[Minato]

Start	End	DAYS	DAY kWh	NIGHT kWh	Average kWh/Day	Average kWh/Night	Nightay Ratio	Day Rate	Night Rate
04-Sep-20	30-Sep-20	26	178	565	6.85	21.73	3.17	£0.243	£0.048
01-Oct-20	31-Mar-21	181	1866	5905	10.31	32.62	3.16	£0.232	£0.048
01-Apr-21	13-Jul-21	103	716	2266	6.95	22.00	3.16	£0.236	£0.083
14-Jul-21	30-Sep-21	78	640	2974	8.21	38.13	4.65	£0.236	£0.083
01-Oct-21	05-Dec-21	65	796	3700	12.25	56.92	4.65	£0.257	£0.098
06-Dec-21	31-Mar-22	115	3212	6335	27.93	55.09	1.97	£0.257	£0.098
01-Apr-22	30-Sep-22	182	2226	5513	12.23	30.29	2.48	£0.354	£0.135
01-Oct-22	02-Oct-22	1	27	67	27.00	67.00	2.48	£0.474	£0.075
03-Oct-22	07-Dec-22	65	822	3735	12.65	57.46	4.54	£0.474	£0.075

So I was trying to see how my usage compares to before I switched to Octopus in April last year. Managed to find an old spreadsheet I made a couple of years ago, when I was trying to make sure we were using as much power at night as possible rather than in the daytime to minimise costs.

Looks like even back then the usage was similar of 60-80kW a day, this was before we had any EVs and a bit less usage overall in terms of appliances and activity in the house.

My split AC is currently drawing 1watt switched off

That's good to know, thank you.

 

[Minato]

In the winter it's not how much you can generate but how much you can store during the off peak period. Even on a bad solar day I run my house on 8.5p electric all day then export what is left for 15p kWh. Soon my imports will be 7p kWh when I get my charge point installed.

Sounds like you've got a big house, if you have plenty of space for panels then a large system will generate well in the summer, which potentially builds up credit for the winter, couple it with batteries and there is plenty of savings to be had. Our gas and electric has been negative two years running.

Good point tbf, if I can generate >60kW in summertime then at least those months would be free.

Haven't looked into it too much yet as I've heard prices of panels are constantly decreasing, and I'd want to get loads of panels so makes sense to wait a bit I think.