Octopus Agile 30 minute readings don't match other data....

[Drew57]

I've recently had the first multi page monthly bill since our switch to Agile and looked at it properly today.

I'm puzzled about some of the data showing in the "Consumption kWh" column which provides the basis for the bill. Comparing with several other data sources it frequently seems wrong for brief use high energy appliances like the kettle, hob etc..... kWh usage on the IHD always matches within a few seconds to the appliance being turned on, likewise it registers on our Mynergi Zappi and PV inverter Solax-X Hybrid apps & in real time.

However although the bar graphs on the Agile bill follow basically the same mapping as I can see on the history of the other apps, the actual half hourly periods that the usage appears is sometimes several minutes behind the same usage as verified by the others (in a few cases more than 30 or 60 minutes behind - falling into a higher cost/kWh band, fortunately car charging doesn't look to be affected).

I appreciate that the billing data may not register much when there are a couple of minutes at 1kWh for a kettle in an otherwise low load half hour period but why does an equivalent peak appear in a subsequent low usage half hour which does not correlate with the other information I have? (example - kettle usage every day between 7-7.30 am but on some days the billed usage appears much later & when I check the inverter history, it shows at the correct time for that day)

On checking the bill, I've also noticed that although we often switch other devices on at the point where a significantly cheaper 30 min slot appears, on the bill this is sometimes shown in a higher cost slot, again not correlating with other data or our known usage pattern. I thought that a SMETS 2 meter (Octopus installed 30th July) stored data even when connection is lost and then released it once online again. This suggests that either something may be mismatched or maybe Octopus manually fill in the blanks to complete the bill and the discrepancies are during those periods?

I'm wondering if anyone else has experienced similar or can explain this - or maybe I'm missing something obvious.

Why does the IHD (which is getting real time data) always seem to match correctly to the house draw but the bill which presumably uses exactly the same information from the same meter appear to sometimes show it differently?

 

[bitmanEV]

My communication with Octopus;

Quick question about Agile; So now we have those 30 minutes kWh slots. So lets say I'm in slot 11:00 - 11:30 with a price of £0.14 now using a shower that takes 9kW for 5 minutes (lets suppose it's the only apparatus use electricity) how do I get billed? is that for the 5 minutes or for that whole 30 minutes slot as I'm not sure how accurate these so called Smart Meter are. The wireless display indeed shows this 9kW for a short time about 5 minutes

Hi, Thanks for getting in touch. So you'll only be billed for the electricity you've used - using your example, if you use 1kWh at 11:05am, then you'd pay £0.14. If you use 10kWh instead, you'd pay £1.40. The key thing is just what 30 minute time slot you are using that energy in. The meter will be able to record exactly how much is being used at what time. So you wouldn't be charged a full half hour of energy if you've only used something for a few minutes, for example. Hope that makes sense! Let us know if any questions. Thanks,

Hi, When looking at the Agil paper bill there’s a Blue and Red line. What’s the line of the actual usage? We understand the black bars what’s the £ kWh per 30 minutes Also how are we billed? Is it the full amount every month or are we still paying a fixed monthly payment as it seems like it? Back in Spain we pay every month the exact € used kWh (hence different € per month)

Hey there, The best place to look at usage is in your online account. This shows the 30 minute data and how much was used in each period. In terms of payments you will pay a monthly direct debit as all customers are now on a monthly billing cycle. We check your usage every 45 days against your monthly payment and will email you if we feel it would be good to amen your payment either up or down.

Hi, We got these usage docs from the on-line account... And indeed it shows the 30 min blocks but my question is what does those two colour lines (blue Average daily consumption (across this bill) & red Unit rate p / kWh) in plain english mean?

Hey, So the blue blocks tell you your energy consumption every half hour and red line will show the changes in the unit rates as this tariff gives you access to half hourly changes in the pricing (per kwh) Hope that helps.

 

[twlr]

I would have thought the smart meter just reported back the meter reading every 30 mins rather than tracking individual usage and summing it up, so you get charged the difference between that reading and the one 30 mins prior multiplied by the rate for that period.

 

[Drew57]

@twlr I agree that is how Octopus arrive at the 30 min consumption figures & how the meter must work. I'm referring to reported kWh usage figures only, the rate is shown separately on the bill & is correct for the NW region where I live.

That doesn't explain why the bill summary sometimes shows very low usage for 30 min slots where I know (& can see elsewhere) a certain appliance was used but high usage later when nothing other than background load was being drawn (around 250Wh in my house).

 

[AndrewGR]

Are you confusing kWh and kW? And I very much doubt your home ever draws 250 kW let alone running up 250 kWh in a 30 minute billing slot. Background use in my home is around 250 W so in a 30 minute slot in the early hours I would expect to see a bill for around 125 Wh (0.125 kWh). Using a 3 kW kettle for 2 minutes would only register 0.1 kWh - not much above the background use in any given 30 minute slot.

 

[Drew57]

Thanks for pointing that out @AndrewGR - you are correct, I should have put 250w & yes my bill does contain a lot of 0.11, 0.12 & 0.13 kWh night time readings if no timers were set.

Your explanation with the kettle example also makes a lot of sense. My question about the relative energy spikes is mostly about trying to understand the logic of why they appear at different times on the bill vs my homes’ other energy apps (which always correlate with switching an appliance on & the IHD in real time but sometimes not with the bill).

 

[MrBadger]

For electricity, the IHD 'now' display typically shows near instantaneous power (W), but you are billed for energy (kWh) which is the cumulative use of that power over the 30 minute time period.

For gas, it cannot show power (keeps the meter power consumption low so give it a chance for its internal battery to last 10 years), but will show volume (m3) or energy equivalence (kWh) consumed within the 30 minute interval.

Watch out for 30 minute interval cumulative power totals vs energy displays/graphs. Eg a constant 100W load for the 30 minute interval would be recorded/billed as 50Wh (0.05kWh) energy. If you used that load for 1 jour, then it would show/billed in the graphs as 2 x 0,05kWh (50Wh) intervals even though billed as 0,1kWh (100Wh) overall of energy.

 

[NewbieT]

Don’t forget the bill is in half- hours. So if you use a 2kW appliance for an hour, the bill will show 1kWh for each half hour.

Also need to be careful and check inc or ex VAT when doing calcs. For the API / also need to be careful with GMT/BST.

When something doesn’t look right, recheck your figures. Octopus billing looks fine to me.

 

[LongRanger]

Half hourly data on Go for me looks spot on, literally to the exact events relating to an outbuilding so no general background draw.

I can see periods where just an LED lighting circuit was on (LED strip lights), where I have charged power tool batteries and then also the car charging.

I hadn’t expected to be able to see such granularity straight through the online account - was a very pleasant surprise.

Agile I imagine is harder due to higher charge rates complexity but if the smart meter is correctly logging half hourly readings then it’s just more maths more often.

Does your paired meter display unit show any useful insights ?

 

[Drew57]

...My paired meter display always seems to be in real-time sync with what both the Zappi app and the PV inverter are reporting (except for those periods when connection is lost, usually brief). I rarely look at gas usage but it's there too.

The IHD is only useful for energy, it shows a basic flat rate for cost that is meaningless for Agile. The Bright or Octopus Watch apps provide usage by kWh and accurate Agile cost the following day (both linked to my account/API key).