British Gas Electric Driver / EV Tariff hours: GMT vs BST

RadioValve

I have recently joined the British Gas Electric Driver / EV Tariff [1]. Leaving the wisdom of this choice to some other thread, the question is: Do the cheaper energy hours remain 12am-5am during the summer time (when the clocks go forward one hour), or do they become 1am-6am BST?

I know that this varies with other energy suppliers. For example, EDF clearly documents that the EDF GoElectric hours change from 12am-5am GMT to 1am-6am BST [2] (even when using smart meters), while Octopus clearly documents that the Octopus Go hours stay 00:30 to 04:30 whether GMT or BST [3].

I asked this question to British Gas customer services directly on four (!) occasions, by chat, written enquiry, and by phoning the "EV tariff team" on 0333 202 1054. No one knows any more than the tariff’s web page [1] headline: "Get cheap electricity between 12am-5am and charge your car for less." Their knowledge base system simply does not have any information on whether the hours change or stay the same during the summer time. Even the tariff’s “small print” Terms and Conditions document is silent on this point.

I tried to build confidence by looking at the IHD (In-Home Display), by downloading tariff and consumption spreadsheets from n3rgy.com [4] and by using smartphone apps like Bright [5], but they all provided contradictory information:

• According to the IHD, the cheaper hours are 12am-5am BST.
• According to n3rgy.com [4] tariff spreadsheets, the TOU (time-of-use) cheaper hours are 1am-6am BST (12am-5am UTC).
• According to the Bright app [5], the TOU cheaper hours are 11pm-4am BST.

I suppose it would be reasonable to assume that “12am-5am means 12am-5am”, i.e. 12am-5am GMT in winter and 12am-5am BST in summer, but it is equally reasonable to expect British Gas to be able to confirm that this is the case, ideally in writing on their website — footnote or FAQ — or at least by having their customer services confidently answer the question when asked.

Do you happen to know the answer for a fact? Have you been on the tariff long enough to compare your summer energy consumption spreadsheets against a bill from British Gas? Thanks!

[1] https://www.britishgas.co.uk/energy/ev-tariff-home.html
[2] https://www.edfenergy.com/electric-cars/tariffs
[3] https://octopus.energy/blog/go-faqs/
[4] https://www.n3rgy.com/consumer/
[5] https://play.google.com/store/apps/details?id=uk.co.hildebrand.brightionic

[Deleted User]

You could just choose Octopus as their time-of-use tariffs are not affected by time changes as they set a single register and bill using 30 minute usage data. 

michaels

I can tell you for sure that Bright get this wrong for the EDF tariff so would not rely on them

thozza

I have been through this subject at length with BG this week, if you have a BG installed SMETS2 meter then the off peak 'should' be as advertised, 12.00am - 5.00am all year round, however, if (like me) you have a non BG meter then it may not correct for BST.

I have had to reset my EV charger to 1.00am - 6.00am as BG finally confirmed that the Liberty 101 meter fitted by Symbio was not correcting for BST. I only found this out from looking at the consumption data from n3rgy and the Hugo app.

I did a final check on the meter which saw the TOU tariff switch over at 1.03am (#latenightmoneysaver) when scrolling through by pressing 6 on the meter.

I would like to think at some point BG would put in a system which works like Octopus, but I'm not holding my breath. I would happily switch away but BG gives an extra hour of EV off peak compared to Octopus Go which I need for my commute. 

Scot_39

The switching of meters from GMT/UTC to DST/BST is if anything the new anomaly in many respects.

Some people love the fact that their E7 meter stays on GMT - e.g. they can have a shower in the AM by 8am rather than 7am etc over summer months etc.

My load switching times don't change - not sure if they did even when radio controlled - lost that c5+ years ago. So in winter the cheap night tariff timer counts down towards midnight, in summer it counts down towards 1am on IHD - and the ACLS circuit switches.

The timings were traditionally not controlled by suppliers - but regionally - dependent on network operator.

And as to Octopus - billing on half hourly time slot logging - again - that is not the same as TOU ACLS load switching - traditionally for NSH and HW - which is essentially what the EV tariffs are doing.

Octopus site for instance states that for their E7 - their installed smart meters are 00:30 to 07:30 UTC (GMT old speak) or 01:30-08:30 DST(BST) - so meter is fixed - curiously no regional dependence mentioned.

https://octopus.energy/help-and-faqs/articles/what-happens-to-my-economy-seven-e7-tariff-when-i-have-a-smart-meter-installed/

Does anyone know if the old regional dependencies are still in force ?

And if so - how that / could that or should that apply to EV charging times ?

With BEV sales rising steadily - 1.3m BEV and PHEV in UK - nearly a third of them registered last year - EV load switching - promises to be a significant load switching demand - and may overtake say E7 heating this decade.

RadioValve

Dolor said:

You could just choose Octopus [...] as they set a single register and bill using 30 minute usage data.

Single register — I believe this is about the electricity meter Rate 1 and Rate 2 registers that are used to separately measure peak and off-peak energy usage, right? This answer and the answers from thozza and Scot_39 imply that the British Gas Electric Driver tariff relies on two registers, unlike Octopus Go. This is useful information, thank you! Expanding a bit, also perhaps for the benefit of anyone else reaching this thread, it sounds like there are these two alternative billing methods of “smart tariffs” like EV tariffs:

• “Register-based billing:” The electricity meter itself keeps track of peak and off-peak energy usage in two “registers” (counters) usually named Rate 1 and Rate 2, and electricity bills are based on the reading of these registers from time to time. This is much like the traditional Economy-7 meters that have been around for decades, except that the readings are sent to the supplier automatically every half an hour.
   
• “Usage-log-based billing:” The smart meter sends half-hourly energy usage data to the energy supplier from a single or “total” register, with timestamps, and this data is used for billing. The meter itself does not need to keep track of energy usage at different rates (prices) or time of day. This allows for innovative tariffs like the Octopus Tracker, where electricity prices may change daily according to wholesale prices. In theory, the price of electricity could even change every half an hour, a bit like live currency exchange rates.

It sounds like the British Gas Electric Driver / EV tariff uses the “register-based” billing system, while the Octopus Go tariff uses the “usage-log-based” billing system. (I have not yet had the chance to confirm this myself as I have not got my first British Gas bill yet.)

This matters to consumers in relation to how to verify that 1- their bills are correct, and 2- how the off peak hours change (or do not change) during daylight savings time (GMT vs. BST):

• With register-based billing, consumers can look at their electricity meter display or IHD (In-Home Display) a few minutes before and a few minutes after the expected electricity rate switch time, e.g. at 23:55 and at 00:05 if the rate should switch at midnight, to confirm that the rate has switched. Consumers can also take note (photos) of the Rate 1 and Rate 2 register readings monthly or when bills are produced to check that the bill is indeed using those register readings.
   
• With usage-log-based billing, consumers cannot rely on the electricity meter registers to confirm the time when the electricity rate switches from peak to off-peak (or vice versa), or to measure their off-peak energy usage. In fact, the electricity meter or IHD may actually display different rates that switch at certain times, but billing will ignore this, creating the potential for the meter / IHD to mislead consumers. This is what Octopus documented in a blog post / FAQ item: “What happens to the off-peak period during daylight savings?” [1]. On the other hand, I understand that Octopus provides consumers with the option to download spreadsheets (by logging in to their Octopus account) that reflect the exact data that Octopus uses for billing. If the consumer set their car to start charging at 1am on a certain day and the spreadsheet shows a spike in energy usage at that time, then this confirms to the consumer that Octopus is receiving data from the meter with the correct timestamps (GMT vs. BST), and consumers can expect billing to follow the off-peak hours advertised by Octopus — e.g. 00:30 to 04:30.

[1] https://octopus.energy/blog/go-faqs/

RadioValve

thozza said:

I have had to reset my EV charger to 1.00am - 6.00am as BG finally confirmed that the Liberty 101 meter fitted by Symbio was not correcting for BST. [...] I did a final check on the meter which saw the TOU tariff switch over at 1.03am (#latenightmoneysaver) when scrolling through by pressing 6 on the meter.

I see, thanks for sharing! This proves that things are not as simple as the “12am-5am” tariff headline would like you to believe. So the off-peak hours actually do change in the summer, but only for some customers, depending on their specific smart meter model. If British Gas cannot avoid the exceptions, they should document it on the tariff web page (footnote, FAQ).

thozza said:

I would like to think at some point BG would put in a system which works like Octopus, but I'm not holding my breath.

Is Octopus’ system of “usage-log-based billing” (as defined in my previous post) necessarily better though? I understand that Octopus has also had to go through hoops to compensate for GMT/BST quirks of specific meter models (the meter still needs to correctly apply timestamps to the data packets sent every half an hour, for later processing by the energy supplier). Under the alternative “register-based” billing system, perhaps British Gas could remotely tell the Liberty 101 meter models specifically, and only during the summer, that the time-of-use off-peak hours are “11pm-4am GMT” (as if it was a different tariff). The Liberty 101 would then “do the right thing” (treat 12am-5am BST as off peak) by failing to adjust for daylight savings time.

The “register-based” billing system might not allow for a tariff like Octopus Tracker, but for Octopus Go or British Gas Electric Driver with just two rates, I see more advantages than disadvantages in the meter registers being the “source of truth” for billing, mainly because consumers can rely on what the meter itself tells them about off-peak hours and usage (consider someone not inclined to download and crunch spreadsheets, or without access to them — perhaps the account holder is the landlord). I only wish my IHD would display the Rate 1 and Rate 2 registers (it only displays the total), because going outside to the meter box in the dark is not always fun! (#latenightmoneysaver)

Anyway. For now I can confirm that my “Landis+Gyr E470 (Type 5533)” electricity meter, alongside an “EDMI Standard 420 Dual Band” communications hub, both fitted recently by British Gas, does switch between Rate 1 (peak) and Rate 2 (off-peak) at 12am BST while under the British Gas Electric Driver / EV tariff. I could further correlate and confirm that:

• The timestamps in n3rgy spreadsheets are indeed UTC as per table header (verified against the car charging schedule), at least with my smart meter model, and to be interpreted as “ending at.” For example, a n3rgy timestamp of 14:00 UTC (15:00 BST) is to be interpreted as “the half an hour between 13:30 and 14:00 UTC.”
   
• By contrast, the timestamps in the Bright app are “starting at” and BST (when the user’s timezone is configured as UTC+1 in the app settings), so a timestamp of 14:00 refers to “the half an hour between 14:00 and 14:30 BST.” Except for what Bright says about my TOU (time of use) tariff hours — it says 11pm-4am BST which makes no sense. I suspect a bug in the app.

I think I will not be able to confirm that the British Gas Electric Driver tariff uses “register-based” billing until I receive my first bill (and even then, only maybe), but as long as it does, my off-peak hours are indeed 12am-5am BST with my specific smart meter and communications hub models.

[Deleted User]

In theory, the price of electricity could even change every half an hour, a bit like live currency exchange rates.

No theory about it. Octopus Agile has 48 by 30 min unit prices each day. Actual costs are easily checked with third-party Apps.

Geoffers0_0

RadioValve said:

thozza said:

I have had to reset my EV charger to 1.00am - 6.00am as BG finally confirmed that the Liberty 101 meter fitted by Symbio was not correcting for BST. [...] I did a final check on the meter which saw the TOU tariff switch over at 1.03am (#latenightmoneysaver) when scrolling through by pressing 6 on the meter.

I see, thanks for sharing! This proves that things are not as simple as the “12am-5am” tariff headline would like you to believe. So the off-peak hours actually do change in the summer, but only for some customers, depending on their specific smart meter model. If British Gas cannot avoid the exceptions, they should document it on the tariff web page (footnote, FAQ).
...
...
 Anyway. For now I can confirm that my “Landis+Gyr E470 (Type 5533)” electricity meter, alongside an “EDMI Standard 420 Dual Band” communications hub, both fitted recently by British Gas, does switch between Rate 1 (peak) and Rate 2 (off-peak) at 12am BST while under the British Gas Electric Driver / EV tariff. I could further correlate and confirm that:

• The timestamps in n3rgy spreadsheets are indeed UTC as per table header (verified against the car charging schedule), at least with my smart meter model, and to be interpreted as “ending at.” For example, a n3rgy timestamp of 14:00 UTC (15:00 BST) is to be interpreted as “the half an hour between 13:30 and 14:00 UTC.”
   
• By contrast, the timestamps in the Bright app are “starting at” and BST (when the user’s timezone is configured as UTC+1 in the app settings), so a timestamp of 14:00 refers to “the half an hour between 14:00 and 14:30 BST.” Except for what Bright says about my TOU (time of use) tariff hours — it says 11pm-4am BST which makes no sense. I suspect a bug in the app.

...
...

Just joining the party late here, and am in a similar situation too, but hope to throw some light on what I’ve discovered so far

I’ve found a document for the Specification of the smart metering system, (I can't post links)

assets dot publishing dot service dot gov dot uk/government/uploads/system/uploads/attachment_data/file/68898/smart_meters_equipment_technical_spec_version_2.pdf

which confirms the data/ timings of the half hourly periods as the amount of energy  used in a half hour period, measured from the start time of that period

5.4.8.9 Half hour profile data ESME shall be capable of recording in each 30 minute period (commencing at the start of minutes 00 and 30 in each hour)…
… the following information (including the UTC date and time at the end of the 30 minute period to which the data relates) in the Profile Data Log(5.6.4.28):
i.                     Consumption;
ii.                    

 It also confirms times are always stored as UTC

4.5.3.25 Tariff Switching Table
A set of rules for allocating daily Consumption to a Tariff Register for Time-of-use Pricing and … 
…The rules shall support allocation based on:
i. day, days and day ranges; and
ii. date, dates and date ranges.

All dates shall be specified as UTC.

In my particular situation, to see the actual raw data which must be being used for billing purposes

1.    I  have the “Bright” app on the phone which gives a visual display of the usage.

2.    You can download the ½ hour data from Bright’s website at (I can't post links) www dot glowmarkt dot com/pages/property/energy-data (you need to be logged into your account to see this)

3.    The base data’s time is in Zulu(GMT) time

epochTimestamp,kWh,dateTime
1690498800,0.861,2023-07-27T23:00:00.000Z
1690500600,1.018,2023-07-27T23:30:00.000Z - usage between 23:30 – 00:00 on the 27th
1690502400,0.986,2023-07-28T00:00:00.000Z - usage between 00:00 – 00:30 on the 28th
1690504200,0.979,2023-07-28T00:30:00.000Z

 4.    I have created an Excel analysis, showing how the data can be interpreted using GMT or BST

5.    The Bright app is applying the GMT+1 correction so the data you see on their app for the 27th shows the data as “starting from” the hour, which I think is correct,  as it’s viewing the base GMT data from the viewpoint of BST

6.    The Eon  Next app however appears to use the GMT data as supplied with no BST correction, so my EV charger actually came on at 00:05 BST on the 28th , but the daily totals shown by Eon have that hour starting at 23:00 on the 27th

 

7.    So my Excel BST (purple) calculation on the right agrees with Bright , and my GMT calculation (blue) on the left agrees with Eon 

8.    These however are just examples as to how the data is being interpreted and displayed to the consumer via the apps. 

9.    The real  issue will come with the interpretation being used to calculate the bill – in my case I fear I may have to set my EV charger to run  from 1am to 8am to get the Midnight to 7am cheap rate 

 

thozza

I just reset my EV charger to 01.00 to 06.00 so that I get the off peak rate, this is for the BG Electric Driver tariff which gives 5 hours.

BG confirmed that if the smart meter does not give them the correct time, there is nothing they can do about it, usually this is because it was not one of their own meters.

As I outlined above, BG don't use half hour readings for this tariff, it is effectively an E7 type tariff where they only take two register readings (on and off peak) for billing purposes. 

I sat next to the meter (not IHD) to confirm the switch between on and off peak occurred at 01.00+/- before changing the EV charger, I suspect you might need to do the same. 

Geoffers0_0

thozza said:

I just reset my EV charger to 01.00 to 06.00 so that I get the off peak rate, this is for the BG Electric Driver tariff which gives 5 hours.

BG confirmed that if the smart meter does not give them the correct time, there is nothing they can do about it, usually this is because it was not one of their own meters.

As I outlined above, BG don't use half hour readings for this tariff, it is effectively an E7 type tariff where they only take two register readings (on and off peak) for billing purposes. 

I sat next to the meter (not IHD) to confirm the switch between on and off peak occurred at 01.00+/- before changing the EV charger, I suspect you might need to do the same. 

Yes - I'm now charging my EV from 1am to 8am BST (which is 12-7 GMT) since ALL smart meters' data for TOU tariffs is sent to the centralised DCC database in 1/2 hour totals based on UTC (ie GMT).

This data is then forwarded from the DCC to the particular supplier (in my case Eon - in yours BG) which is the first time they actually get to see this data. From this they have all the usage kWh data to calculate the bills, which hopefully they do correctly!.

My examples above show how I've sourced the raw 1/2 hourly DCC usage data, to compare with the visual display on the IHD & EonNext app

Unfortunately Eon are currently way behind the game, as they don't yet push the dual-tariff rates to the meter, so consequently the meter and it's (slave) IHD display, although showing the correct power usage have no way of calculating the true cost.