What are my off-peak hours for Economy 7? — Bulb Community

What are my off-peak hours for Economy 7?

The majority of Economy 7 meters display the on and off-peak timings on the front of or just next to the meter.

But not every single meter has this information and they are not always accurate.

Economy 7 hours vary region by region. So if your meter does not display the timings, you can find out the list below to find out when your off-peak hours kick in:

Region Number:
10 Eastern area: 7 hours between 11pm and 7am
11 East Midlands area: 7 hours between 11pm and 7am
12 London area: 7 hours between 11pm and 7am
13 Merseyside & North Wales area: 7 hours between 12am and 8am
14 Midlands area: 7 hours between 11:30pm and 8am
15 North East area: 7 hours between 12:30am and 7:30am
16 North West area: 7 hours between 12:30am and 7:30am
17 North Scotland area: All meters have different settings
18 South Scotland area: 7 hours between 10pm and 8:30am
19 South East area: 10.30pm to 5.30am and 12.30am to 7.30am
20 Southern area: 7 hours between 11:30pm and 6:30am
21 South Wales area : All meters have different settings
22 South West area: All meters have different settings
23 Yorkshire area: 7 hours between 12:30am and 7:30am


Check out the new help centre article for more details on economy 7 meter timings. It explains what happens to Economy 7 timings when the clocks change and how to find your region numnber.

Thanks to @Allanr and @RichyB for pointing out that our Help Centre article for economy 7 rates was not that helpful.

We've given it a makeover and it's now live on our Help Centre.

Comments

  • edited November 2018
    Thanks @Eleanor at Bulb - that should be very helpful for people. It might be worth noting that not all Eco7 meters are on the times for that region (as we've seen here on the forum) - would it be worth listing the different time codes in addition (to be honest, I'm not sure if they vary per DNO [I think it's implied they do, but I haven't found anything concrete] and I assume the time code on the MPAN takes precedent over the DNO standard times and that meters will always follow the timecode...).

    If you could just clarify that for us (at least just for my own personal interest), it'll be appreciated. Would it be also worth cross-linking the help article back to this thread to keep discussion in one place (something like 'Read/discuss this post on our community forum at [link]'?)

    (added: It might also be worth noting that meters will not follow the 'real time' correctly and could be 'out' by 30 minutes either way to help balance the grid/prevent spikes - so it'll be worth just checking the 'meter time' against a watch/clock/phone to see what 'jitter' is set).
  • Hello @Eleanor at Bulb. My region is 27 according to the bill bulb is sending me. Can you please tell me which are my off-pick hours?
  • Hi @mmaria,

    Areas 24-32 are classed as 'Independent Distribution Network Operators' IDNO and like me (hello fellow 27er!), you are serviced by 'GTC' akak 'The Electricity Company Ltd'. I assume you are probably a newish build property as well?

    Since these IDNOs aren't geographically specific, it's a little tricker to provide guidelines, but if you look at your bill, you'll see the MPAN/S-Number


    If you look at the 'time code' section (top middle), you should be able to work things out from:

    (from https://community.bulb.co.uk/discussion/comment/21447/#Comment_21447 )

    Code Time
    500 Single rate
    501 Single rate
    801 Single rate
    802 Single rate
    803 Cheap: 23:30 – 06:30 clock time
    804 Cheap: 23:30 – 06:30 clock time
    805 Cheap: 23:30 – 06:30 GMT
    806 Cheap: 23:30 – 06:300 GMT
    807 Cheap: Midnight – 0700 GMT
    808 Cheap: Midnight – 0700 GMT
    809 Cheap: Midnight – 0700 GMT
    810 Cheap: Midnight – 0700 GMT
    811 Cheap: 00:30 – 07:30 GMT
    812 Cheap: 00:30 – 07:30 GMT
    813 Cheap: 00:30 – 07:30 clock time
    814 Cheap: 00:30 – 07:30 GMT
    815 Cheap: 00:30 – 07:30 GMT
    816 Cheap: 00:30 – 07:30 clock time
    817 Cheap: 00:30 – 07:30 clock time
    830 Cheap: 01:00 – 08:00 clock time
    831 Cheap: 01:00 – 08:00 clock time

    Mine's 801 (Single Rate) as I've only got a single rate meter (this corresponds with the profile class [top left digits] which 01= domestic single rate and 02 = domestic economy 7)
  • edited December 2018
    @RichyB you beat me to it!

    Hope that helps @mmaria. Fire away if you have other questions.

  • edited December 2018
    @RichyB
    RichyB said:

    It might be worth noting that not all Eco7 meters are on the times for that region (as we've seen here on the forum) - would it be worth listing the different time codes in addition (to be honest, I'm not sure if they vary per DNO [I think it's implied they do, but I haven't found anything concrete] and I assume the time code on the MPAN takes precedent over the DNO standard times and that meters will always follow the timecode...).

    To find out an individual's E7 timings, we need to know their Standard Settlement Configuration Id (SSC) and Regime Id (TPR).

    We have a TPR reference sheet that we use to cross-reference for an individual meter. It's a 22 pages long document :s

    As we don't tell our member's what their TPR is, we don't tend to share the document. But I'd be happy to email over a copy to you if you'd like?

    I've passed over your comments about adding the "jitter" settings to @Denise at Bulb. This would be useful for the fringe cases.
  • Oh, and there's me thinking that trying to understand my E7 hours might be simple!! I have an electric car (yeah, trying to do the right thing, but thwarted once again), and therefore charge overnight. This typically takes 6-7 hours, so I naturally want to maximise my E7 period. I've only just found out that there is a variance (I'm in R14), but my particular hours are 00.30-07.30, which doesn't suit my needs. So the questions: a) why is the whole issue around E7 so opaque, and just so bl**dy difficult to understand? b) why does bulb not tell customers either when they sign-up or on the statements, c) how do I change my hours, and d) if E7 is about managing demand, why is it so random? #confused.
  • @Adrian_O

    My understanding is that the E7 hours with Bulb are exactly the same as they were with your previous supplier, that is in your case 00.30-07.30. Also my understanding is that these hours are meter dependant and cannot be altered.

  • edited January 9
    Adrian_O said:

    a) why is the whole issue around E7 so opaque, and just so bl**dy difficult to understand?

    It's historic, and not specific to Bulb.
    Adrian_O said:

    b) why does bulb not tell customers either when they sign-up or on the statements,

    Indeed, that would be useful.
    Adrian_O said:

    c) how do I change my hours,

    You can't. Well, I suppose you could move house to a different region but that seems excessive.
    Adrian_O said:

    and d) if E7 is about managing demand, why is it so random? #confused.

    Economy-7 has generally been used for properties with electric storage heating. These heaters often run from a dedicated "night" circuit that is controlled by the meter timer. In order to prevent a massive in-rush current when all E7 meters kick in at the same time, the E7 times are typically staggered between regions.

    You may like to take a look at the new Bulb trial of their smart time-of-use tariff which has an over-night period from 11pm-7am. Provided you can limit your usage during the peak 4pm-7pm period, you should be able to save.

    My 24kWh Leaf takes about 2 hours for a 20%-80% charge with a 6.6kW on board charger and 7kW supply, and something like 4.5 hours for a 100% charge due to rate tapering above 80% state-of-charge, so the night rate on the TOU tariff is more than long enough, but as you know charging times do vary with battery size and on-board charger capability. A charging time of 6-7 hours is either a very big battery or a very low specification on-board charger. I know the 6.6kW charger on my Leaf was an optional upgrade when sold new, and so I specifically looked for a vehicle with that when I was checking out the used market to avoid long home charge times.
  • Hi @Adrian_O

    @Hooloovoo has answered your questions pretty thoroughly.

    I'll be able to expand on "b) why does bulb not tell customers either when they sign-up or on the statements"

    As we don't receive all the data about your meter when you first make the switch, we're unable to add specific information about the meter timings to the Welcome Pack. We receive your 'meter technical details' a bit later in the 21 day switch process.

    But there are a few things that we'll be doing to improve communication with economy 7 users.

    One of which is looking to add information to your Bulb account. Currently, an E7 user will see their tariff details in the 'account & tariff info' section. We'll be looking to add more specific information about your meter and meter timings.

    Thanks for your thoughts and questions.

    Let me know if we can help with anything else.
  • Thanks @Hooloovoo I suppose E7 has a real hang-over from the storage heater boom era as you say, and instead of recognising that electric vehicles could be charged using it, we carry on as before :anguished:
    My car (30kw Leaf will typically take 7-8 hours on my overnight PodPoint charge. It's almost 2 years old now, so perhaps I should get it checked out!

    @Eleanor at Bulb Thanks for your explanation, BUT I do think that it should be more obvious to customers how to find out about their particular E7 hours. Having raised the issue with others who have E7 meters, none of them knew how to find out - none were Bulb customers though :(
  • Adrian_O said:

    Thanks @Hooloovoo I suppose E7 has a real hang-over from the storage heater boom era as you say, and instead of recognising that electric vehicles could be charged using it, we carry on as before :anguished:
    My car (30kw Leaf will typically take 7-8 hours on my overnight PodPoint charge. It's almost 2 years old now, so perhaps I should get it checked out!

    That sounds about right for a Leaf with a 3.3kW on-board charger.

    You should have looked out for one with the uprated 6.6kW charger =)
  • Hooloovoo said:

    Adrian_O said:

    Thanks @Hooloovoo I suppose E7 has a real hang-over from the storage heater boom era as you say, and instead of recognising that electric vehicles could be charged using it, we carry on as before :anguished:
    My car (30kw Leaf will typically take 7-8 hours on my overnight PodPoint charge. It's almost 2 years old now, so perhaps I should get it checked out!

    That sounds about right for a Leaf with a 3.3kW on-board charger.
    You should have looked out for one with the uprated 6.6kW charger =)
    Podpoint's home DC charging right?

    The most basic charger they do will only put out 3.6kW so which one do you have?

    How fast does your leaf charge when DC fast-charging elsewhere?
  • mowcius said:

    Podpoint's home DC charging right?

    No. All home charging is AC. The EVSE wallboxes are basically just fancy outdoor sockets with some safety systems.

    So-called "destination chargers" at shopping centres etc. are also AC charging. They are the same as home chargers but with some way of billing the customer.

    The new vehicle-to-grid system being trialled by OVO are home DC, but since the off-board AC<->DC converters are bulky and expensive, general normal-rate charging is AC and makes use of the on-board charger.

    Only "rapid chargers" are DC, which bypasses the car's own on-board charger and connects straight to the battery.
    mowcius said:

    The most basic charger they do will only put out 3.6kW so which one do you have?

    Pod Point make three types of home wallbox. 3.6kW (approx 16A), 7kW (approx 32A), and 22kW (approx 32A with three-phase).

    I have a 7kW Pod Point, and my car has a 6.6kW on-board charger. Many older EVs have only 3.3kW on-board chargers, so even when connected to an EVSE that is capable of supplying more current they are limited by the capability of the on-board charger.
    mowcius said:

    How fast does your leaf charge when DC fast-charging elsewhere?

    Rapid charging over Chademo is 50kW, although many rapid chargers are limited to 105A at 400V so they max out at 42kW. On a trip to Ireland last year, some of the rapids over there can do 120A so give a true 50kW at full rate. Tesla superchargers run at 120kW. The newer chargers with CCS connectors are 150kW with up to 350kW planned.

    The nature of charging lithium-ion batteries means that they charge at the full rate only up to about 80% at most, after that the charge rate tapers off and gets much slower, to the point where you may as well disconnect and continue your journey.

    My old Leaf has only the 24kWh battery (with about 21kWh usable) so on the motorway can only do about 80 miles between charges. WIth the current state of the rapid charging networks you can't trust it's going to be working when you arrive so you always have to have a plan-B, meaning realistically its 60 miles between charges. A 15%-80% charge takes about 20 minutes, meaning planning for a 20 minute stop every hour of driving. Clearly this is not great, but I only do long journeys occasionally so it doesn't matter, and I rather enjoy it as an EV early adopter. For my general commute I can get to work and back twice between charges. The newer vehicles with 40-60kWh batteries are obviously much more capable.
  • edited January 14
    Hooloovoo said:

    mowcius said:

    The most basic charger they do will only put out 3.6kW so which one do you have?

    Pod Point make three types of home wallbox. 3.6kW (approx 16A), 7kW (approx 32A), and 22kW (approx 32A with three-phase).

    I have a 7kW Pod Point, and my car has a 6.6kW on-board charger. Many older EVs have only 3.3kW on-board chargers, so even when connected to an EVSE that is capable of supplying more current they are limited by the capability of the on-board charger.
    It's worth noting that the cable used can also restrict the charging speed. If you have a 7kW EVSE, a 6.6kW capable leaf but only have a 16 amp cable you will be limited to 3.6kW charging.

    On the Leaf dashboard you can toggle the display to a point where it shows an estimated charge time, if you have a 6.6kW capable leaf it will show two estimates. Once you have begun charging it shows dashes with just the relevant time shown for the closest applicable rate which it is actually charging.

    It occasionally happens that a 7kW EVSE has been installed but incorrectly configured to be limited or throttled to a lower speed.

    If you don't have a dedicated EVSE and are relying on the granny charger / 3 pin plug, this is limited to 10amp approx 2.4kW which takes considerably longer so even if your leaf is only a basic 3.3kW it's worth getting a dedicated EVSE fitted as that will shave about a third off the time taken to charge.
    Hooloovoo said:

    mowcius said:

    How fast does your leaf charge when DC fast-charging elsewhere?

    My old Leaf has only the 24kWh battery (with about 21kWh usable) so on the motorway can only do about 80 miles between charges. WIth the current state of the rapid charging networks you can't trust it's going to be working when you arrive so you always have to have a plan-B, meaning realistically its 60 miles between charges. A 15%-80% charge takes about 20 minutes, meaning planning for a 20 minute stop every hour of driving. Clearly this is not great, but I only do long journeys occasionally so it doesn't matter, and I rather enjoy it as an EV early adopter. For my general commute I can get to work and back twice between charges. The newer vehicles with 40-60kWh batteries are obviously much more capable.
    I consider myself to be a late-early adopter. I have a 2016 30Kwh leaf with 6.6 charger such that I could commute with no need to charge during the day (I trialled a 24Kwh leaf but this did not quite have the capacity to achieve this). There is a dual post 7Kw chargepost near work which can be used (handy on rare occasion my home charge point fails e.g powercut or big journey in evening required), but if the 2nd socket becomes activated it drops to 3Kw so with a max 4 hour stay it no longer fills my battery if I am low on charge as it is in near constant use nowadays. We are lucky that if needed there is a good pair of rapid charge units in Nantwich about 10 miles away South, and 3 ecotricity Rapids at Lymm services about 15 miles North of our home.

    In early 2017 we became a two electric car family, my wife obtained a 2nd hand 2015 22Kwh Renault Zoe. This was great for local journeys and it could utilize the full 7kW of our home charger so if both cars were low we would take the Zoe for a quicker charge at home and being a smaller car it used that electric more efficiently. My Leaf became the long distance car (rather than just my daily commute) as it had the larger battery, more comfortable than the Zoe and could rapid charge quicker (the Zoe is AC rapid charge rather than DC so a bit slower at 43Kw rather than 50Kw but a short 15 to 20 minute rapid stop could do wonders for the Zoe so very capable).

    Both cars are fully charged overnight on economy 7 (two separate 7Kw wall chargers fitted)

    The Renault Zoe however parted ways after 15 months and now have a 2015 Vauxhall Ampera. This only has 10Kwh useable battery so only gets 40 miles before a range extender petrol engine kicks in to provide more electricity. This is now our super long range vehicle as my Leaf takes too long to travel the 440+ mile journey to North East of Scotland and certainly would not have been possible to do the 540 mile journey we achieved in the Ampera in a single day in October!

    In my Leaf I do upto 90 miles on the 1st stop then after 30-35 minutes recharge the stops are approx 70 mile intervals at well trusted sites (2+ Rapids or alternatives nearby).

    The return journey was always the worst as I would not have a 100% battery to start with and the exact plan was unknown so the initial charging stops would be only roughly planned as possibilities. In the coldest of winter I would reduce my speed from 70mph down to 50mph so I could achieve the same well known stops and distances as the heater / bad weather does zap the battery.

    My last super long range trip in my Leaf on 2nd Jan 2018 we did charge up at one of the new rapid charging hubs in Dundee and rapid charging locations in general are increasingly popping up across the UK (Scotland is still best laid out though in my experience). Realistically I would recommend the 30Kwh Leaf an occasional single day journey comfortable max at about 350 miles only if you are prepared to stop for 30 mins every 90 minutes and the rapid chargers exist were you need them - great if you have dogs on the journey but eventually gets tedious after 5 stops!.

    Sadly the 40Kwh leaf despite the bigger battery is less capable beyond 250 miles due to the rapidgate issue lack of thermal cooling so it will be a few years before I can afford a 60 / 75 kWh battery that will be more suited to the super long journey (approx 2 or 3 times a year) at which point the Ampera will be replaced with perhaps a 40Kwh Zoe and we return to a two car full electric once again.

    In the meantime I will be keeping my Leaf for a few more years, it will have done 50,000 miles before my 3 years PCP is up in May, whilst trying to use the Ampera in electric only mode as much as possible whilst it is doing shorter journeys.

    The ampera does not have rapid charging capability and a max 3kW charge on our home charger and thus it can only be destination charged at the end of a journey. Whilst in Scotland last we were able to charge the Ampera overnight at the cottage to provide the first 30 miles in electric drive per day due to the freezing conditions at the time.
  • Adrian_O said:


    @Eleanor at Bulb Thanks for your explanation, BUT I do think that it should be more obvious to customers how to find out about their particular E7 hours. Having raised the issue with others who have E7 meters, none of them knew how to find out - none were Bulb customers though :(

    It's been noted and we will be working towards clearing this up.

    Let us know if you have any further thoughts or ideas on how you'd like the communicated.
  • Sadly the 40Kwh leaf despite the bigger battery is less capable beyond 250 miles due to the rapidgate issue lack of thermal cooling so it will be a few years before I can afford a 60 / 75 kWh battery that will be more suited to the super long journey (approx 2 or 3 times a year) at which point the Ampera will be replaced with perhaps a 40Kwh Zoe and we return to a two car full electric once again..

    The current Leafs have now got a firmware update to improve the charge throttling situation - the batteries are now allowed to get a bit warmer, but no warmer than competitors charge their batteries at (Tesla for example). It seems Nissan were maybe a bit too conservative before.

  • edited January 14
    mowcius said:

    Sadly the 40Kwh leaf despite the bigger battery is less capable beyond 250 miles due to the rapidgate issue lack of thermal cooling so it will be a few years before I can afford a 60 / 75 kWh battery that will be more suited to the super long journey (approx 2 or 3 times a year) at which point the Ampera will be replaced with perhaps a 40Kwh Zoe and we return to a two car full electric once again..

    The current Leafs have now got a firmware update to improve the charge throttling situation - the batteries are now allowed to get a bit warmer, but no warmer than competitors charge their batteries at (Tesla for example). It seems Nissan were maybe a bit too conservative before.

    Yes interesting development that would help a bit. However I am more than happy with my current Leaf 30 for it's intended purpose of the general daily commute. I will wait and see what the new forthcoming Leaf e+ 60Kwh version is like on long distance hoping it has at least some thermal cooling assistance and ideally 100Kw charge capability for when ultra Rapids are rolled out, should be a good buy 2nd hand in future years.

    I would be unlikely to do more than 2 hour driving stints in a single session on super long journeys and 30-40 minute stops to recharge would be ideal with a bit in reserve for flexibility.

    Most of the time my leaf is charged up at home either overnight on economy 7 or shortly they will also be trickle charged via a new zappi charger over summer using up the solar power whilst it or the Ampera is sat on the drive in strong daylight.

    Actually I am also considering getting a small battery storage system and changing to the bulb smart tariff once the smart meters are rolled out with the battery storage used initially to cover the peak period 4pm to 7pm.
  • It would make sense that Nissan adds active cooling to the Leaf in the next generation. It seemed an odd omission when they're producing the e-NV200 with it.

    Actually I am also considering getting a small battery storage system and changing to the bulb smart tariff once the smart meters are rolled out with the battery storage used initially to cover the peak period 4pm to 7pm.

    Have you done any calculations on the payback period here?
    It seems that it's rarely worth it and personally for environmental reasons I'd rather investment was made on a national level on battery storage systems.
    It takes less resource and energy to construct large scale battery farms than many small batteries and their associated chargers/inverters.

  • edited January 14
    mowcius said:


    Actually I am also considering getting a small battery storage system and changing to the bulb smart tariff once the smart meters are rolled out with the battery storage used initially to cover the peak period 4pm to 7pm.

    Have you done any calculations on the payback period here?
    It seems that it's rarely worth it and personally for environmental reasons I'd rather investment was made on a national level on battery storage systems.
    It takes less resource and energy to construct large scale battery farms than many small batteries and their associated chargers/inverters.
    Rough calculations only at present. Initially I was looking at getting a large Tesla Powerwall 2 or similar about 13Kwh capacity at the time of installing the solar panels back in 2017 but decided against it. The solar panels made sense to offset the increased daytime running costs due to economy 7, the solar panel cost added to part of the mortgage. Despite the shaded element of my panels the overall FIT payments have easily paid for the extra payment payable on the mortgage so paying their way which will gradually increase each year and that's before the saving of electric usage.

    I had fitted an energy monitor element to the solar edge so I have a good idea of our electrical usage along with a diverter to an immersion element that i had added to heat the hot water tank (its a small thermal store that also provides the central heating) when there is surplus energy.

    Whilst we try and avoid charging the electric cars during the day the Ampera has such a short range that it makes sense to charge that up again if required to reduce the far more costly petrol usage. It's also difficult to run the washing machine overnight etc. even if it did have a timer it often needs to run during the day as well.

    Last year I rigged up the granny charger to an external socket that only energises if the solar panels are producing 1.8Kw or more of the 2.4Kw required of the granny charger this is crude 15 minute block checks but proved more effective than expected but due to a flaw only works once the hot water tank is full.

    The zappi is more advanced than this and can vary down to 1.4Kw but has a boost button such that if the Ampera is empty it can fill at its max 3.3Kw rate - useful to avoid the more costly petrol. I have a pre-order on the new untethered Zappi.

    Our electric import on economy 7 is split approx 78% night rate 22% day rate - most of the day rate is over the winter period when the panels are not producing much.

    The solar panels generated 3.5Mwh in 2018, 77% was self consumed with 800Kwh exported to the grid. The immersion element consumed approx 800Kwh so saving £30 of gas, however that £30 could have been £70 night rate electric, or £130 at day rate, or £270 at the smart peak rate.

    Obviously that's best/worse case scenario but for me it would not be worth moving off economy 7 to the bulb smart tarrif without having battery storage to cover the peak 3 hours. If take an average 2Kwh evening peak over 365 days thats 730 kWh that would be about £130 more expensive but if time shifted from the night rate (or better free from solar) then it begins to make sense.

    The bulb smart tarrif night rate is currently the same as the economy 7 but the day rate is only marginally more expensive whereas the economy 7 day rate is effectively double the night, so less need to avoid charging during the day and can then follow other mantras such as ABC (Always Be Charging) particularly the Ampera and let the Zappi choose the most cost effective charging rate.

    The house battery storage can fill in the spikes such as the kettle and toaster being on whilst solar is not at peak generation.

    The Zappi should overrule the hot water element (gas is still cheaper despite the increase last year) and similarly it is best to go straight to the cars battery rather than any house battery storage to be used overnight.

    The smart tariff has an expensive 3 hour evening peak, so this is the main period the battery storage is required. Depending on how much cooking is involved we use over this period between 1 and 4 kWh. Thus I am considering a modular battery storage built up of 2.4Kwh modules. Ideally 2 or 3 units would be nice but I may start with just 1 for the summer (however need more than 1 to cover heavy cooking / kettle surges without any solar) and purchase an additional module later on.

    In winter the battery could be charged up overnight on cheap rate and capacity reserved for the evening peak usage. If I have two or three these could be more flexible e.g. only partially reserved and topped up more by solar during the day for more of the year.

    The idea is to if at all possible have one of the cars charging on the zappi car charger first as primary user of solar, any surplus then to go into the house storage battery, only when that is full to top up the hot water cylinder at the end of the day the gas boiler tops up the hot water if required ready for the morning shower.

    However I need to delve into more realistic figures and cost of the battery storage to see if it will break even with cost of loan or just stick with the existing economy 7 setup. The Ampera has increased our daytime usage so this does weigh more heavily into the equation than it would have done had we still had the Zoe, but having a battery storage system would also help simplify life a little too in other respects.
  • edited January 15
    I'd be very interested to see your calculations when you've finished working it out.

    Personally I suspect that accounting for the yearly decrease in battery capacity the payback period may be close to never.


    On a national scale, the payback periods could potentially be more like years rather than decades due to the insane costs of balancing the grid using gas and other quick response generators/consumers.
    I don't believe our balancing costs are as steep as those in Aus, but it's interesting nonetheless:
    https://electrek.co/2018/12/06/tesla-battery-report/
  • edited January 15
    mowcius said:

    I'd be very interested to see your calculations when you've finished working it out.

    Personally I suspect that accounting for the yearly decrease in battery capacity the payback period may be close to never.

    Ok a stab at the figures - here goes at current tariff.

    Predicted imported day units 2500 @ 16.5p = £412.50 (up from actual 2200 of last 12 months to account for the Ampera change of car)

    Let's split that for easier comparison into an assumed evening peak average of 2Kwh over 365 days = 730 kWh.

    Evening peak 730 @ 16.5p = £120.45
    Daytime 1770 @ 16.5p = £292.05
    Total £412.50

    Now apply same split at smart bulb tarrif (no battery storage)
    Evening peak 730 @ 34.16p = £249.37 (extra £128.92)
    Daytime 1770 @ 12.85p = £227.45 (saving £64.60)
    Total £476.82 (increase £64.32)

    Confirms for me switching to smart tariff alone will be more expensive unless we don't cook or watch TV etc!.

    So now assume battery storage added of 4.8Kwh this I believe the minimum to ensure the evening peak is covered including spikes in winter

    To keep things simple I guess the evening peak 2Kwh average will now be covered by the battery filled from half night rate reserved and half free solar attained during the day (as an average throughout the year)
    Additionally the other 2.8Kwh battery capacity will be used early morning and late evening or general overcast periods again assume half night and free solar. 2.8 x 365 = 1022 kWh so let's say 1000 kWh.

    Evening peak 730 @ half of 8.61p = £31.43 (saving £89.02)
    Daytime battery 1000 @ half of 8.61p = £43.05 (saving £121.95)
    Import day 770 @ 12.85p = £98.95 (saving £28.10)
    Total £173.43 (saving £239.07)

    So it may reduce my annual bill by £240 annually or £20 a month. Such a system will likely be £2500+ so looks like payback of 11+ years, similar to the solar panels but better than I worked out with the power wall which was a much more expensive outlay.

    It may be that I could improve on the savings slightly with the aid of the zappi and other change in usage but it's not going to be significantly more than the above it's still going to be 10 or so years.

    I don't see adding further battery e.g an extra 2.4Kwh would be cost effective either as I think it would mostly only be time shift from night to day for half the year and reduce night usage slightly in the summer unless observerd usage showed otherwise in the future.

    If electric costs continue to rise payback will be quicker, or longer if they fall....

    If I can spread that cost over the remaining mortgage similar to how I did with the solar panels and new gas boiler a few years ago it could work (currently looking at battery storage along with other home improvement projects), but it would need to be seen as a longer term investment otherwise and paying more than it saves initially.

    I could perhaps start with a smaller starting system of 2.4Kwh installed, this would still be of use on economy 7 and see if I can observe if it would then be a consideration to try the smart tariff in reality then increasing to 4.8Kwh only if deemed worthwhile later on either tariff.

    Yes battery depreciation of capacity will occur to some extent but I believe that if its 4.8Kwh or above they are not going to be working super hard thus they should be above 80% capacity in 10 years if not overworked. If it was just a single pack 2.4Kwh then it will be working hard charging at max rate and likely discharging at max rate during the spikes always to full depletion.

    Edit - corrected the daytime battery rate calc.

    Also just noticed that the smart tariff night rate is more than 7 hours, starting at 11pm rather than 1am, so there would be a slight benefit there to change, but would not alter much in terms of the battery usage / payback.
  • In your calculations you're not assuming discharging the battery just a little bit (which wouldn't degrade the battery very much), you're talking about quite a significant discharge every day.

    Batteries are getting cheaper all the time, so I think we'll get to a point soon when companies are selling products with decent capacity (and battery management to ensure they last) at a price that makes the payback period worthwhile, but right now I don't think so.

    The degredation is going to add a few years to the payback, then add to that the fact that you're going to be paying someone a few bob to install it, then the warranty will only be for a few years and it might need repairs once or twice...
  • edited 4:32PM
    Hey there @Eleanor at Bulb - sorry for reviving an old thread, but I've just checked my meter and the clock on it is fast by exactly 30 minutes. My time-switch code is 811 meaning 0030 - 0730 Winter / 2330 - 0630 Summer (thanks @RichyB !). Am I right in thinking, then, that my cheap energy is actually 0000 - 0700 Winter / 2300 - 0600 Summer? Or is there a different clock used for switching?
  • Hi @rmuk,

    Since you tagged me, I'll answer - yep, if the meter clock is skewed fast by 30 minutes [i.e. it reads 1700 when it is actually 1730] (which it is allowed to be and is probably intentional to help balance the grid) but your 'scheduled times' are 0030 - 0730, then the 'real time' would indeed be 0000-0700 and 2300-0600 summer. The same clock time that is being displayed by the meter is the one it should use for switching/scheduling (if your meter doesn't have a clock, then it is probably Teleswitched by the Radio 4 time signal- https://en.wikipedia.org/wiki/Radio_teleswitch )
  • mowcius said:

    In your calculations you're not assuming discharging the battery just a little bit (which wouldn't degrade the battery very much), you're talking about quite a significant discharge every day.

    Batteries are getting cheaper all the time, so I think we'll get to a point soon when companies are selling products with decent capacity (and battery management to ensure they last) at a price that makes the payback period worthwhile, but right now I don't think so.

    The degredation is going to add a few years to the payback, then add to that the fact that you're going to be paying someone a few bob to install it, then the warranty will only be for a few years and it might need repairs once or twice...

    Yes with the smaller battery it would be fairly heavy discharge particularly over winter, summer should not be so bad. This is why I would ideally start with two, then adding a 3rd battery module to make 7.2Kwh should somewhat reduce that stress that could lead to increased degradation.

    Having the system fail is a bit of a risk beyond the warranty, just like solar panels are, even within would be a pain.

    Glad you've prompted me to run through the figures though, it has given me a deeper understanding of the potential changes of costs and a bit more to think about. At present I think it's still something I can progress with.

    If battery costs are coming down then it may be worthwhile me holding back a few more months or until there is sign of the smart meters being installed.

    Yes in a few years battery systems are likely to be even easier and cost effective than current and become more mainstream.
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