British Summer Time and Greenwich Mean Time: When are my night rate hours?

At what times do the reduced night rate for electricity apply and how is this affected by the six monthly switch between British Summer Time and Greenwich Mean Time. Currently I’m on the Vari-Fair duel fuel tariff with a reduced night unit rate.

Understand ‘Economy 7’ tariffs are usually midnight to 07:00am but this & GMT/BST effects are not standardised and can be supplier specific. Thanks.

Hi @nuppard

Every dual rate meter switches at a different time. It’s a bit frustrating, but it’s necessary for the industry to regulate the grid. If everyone switched to night rate at the same time, there would be a massive surge at the switch to night rate every night which would be pretty problematic.

Instead, every meter has a schedule, and it will switch rates 30 minutes before or after this scheduled time. It’s the same discrepancy every day, so even though it’s a bit arbitrary, once you’ve worked it out it’ll be the same every day.

I’ve looked into the industry records for you and your meters schedule for night rate is 00:30am - 7:30am. During British Summer time it will be 1:30am - 8:30am.

The best way to find out how much it varies by is to do a kettle test. Boiling the kettle takes a pretty large amount of energy in a short time, so it’s perfect for working out which of your meter’s registers are currently measuring. So, from midnight, try boiling the kettle every 10 minutes or so and note down when it switches to night rate.

This is unfortunately just one of the small faffs of the energy industry.

Thanks for detailed update Will. Don’t understand though how you know my ‘industry records’. Do you mean by this Bulb’s policy although I guess this can’t apply as the issue must be location dependant?

I actually need to know these times to charge my car overnight - a 3,6 kW drain over several hours potentially.

Do you also happen to know Bulb’s policy on smart meter supply please as I’d like one & would hopefully make the kettle test a bit easier! Thanks again.

You’re very welcome @nuppard

The energy industry keeps a database of every energy meter in the country. There are a few organisations involved with, so it’s easier to just refer to it as “the industry”. If you’re interested I’m sure I could come up with a list of which organisation does what. Supplying energy is a complex job, so different organisations do different jobs. We can look up in these databases what the schedule for your meters are. This isn’t set by us, it’s set by the engineer when the meter was installed, so whoever installed your meter will have set it.

Definitely a good idea to have your electric car charging at the right times. Are you able to set a timer for it? That would be ideal.

We will be doing smart meters. We’ll be starting a trial for them next year, so we’ll let you know about that closer to the time.

Yes had a timer installed with EV charge unit. Mechanical & small & fiddly though. Pity no smart meter now, would have thought this should be a priority for Bulb.

@nuppard that’s useful.

Smart meters are definitely up there for us. We’ll start installing them next year, so we’ll keep you in the loop about them.

Hi Will - you seem to be a fountain of knowledge with this stuff, so here goes…

I was going to ask the same q’ - when does my night tariff kick in? Can you tell from my records, or shall I just do the kettle test - that is a bit of a faff though…

Cheers, D

Hi @seardarren, always happy to help.

Annoyingly, we can’t actually see when your meter switches over. Normally we can, but we can’t with your meters I’m afraid. So I’m afraid you’ll have to do the kettle test. Chances are that it’ll be either 23:30 - 6:30, or it’ll be 0:00 - 7:00 though. It’s fairly rare for it to be outside of that.

Sorry that I couldn’t spare you the faff.


Hi. I could also do with knowing my low rate hours, also for charging my car. Can you help or point me in the right direction? Thanks

One of the benefits of my smart/not smart meter is it shows you the rate you’re on (bottom left E1/E2), and switches bang on time…So hopefully it’s the same for everyone once they’re rolled out next year, but no doubt they’ll all work differently :-1:

@anthony7048 Your night rate is between 0015 and 0715 :slight_smile:

Oh I would love a smart meter too! How do night rates compare to daytime rates? We also have PV solar panels so want to economise as best we can.

@louise 4642 The rates depend on what part of the country you are in. Your rates would be:

Day: 14.111p / kWh
Night: 2.470p / kWh

We aren’t going to be installing smart meters for our member’s until the generation two meters are available in mid-2018.

Hi I just signed up, i didn’t realise that I would have two rates is this standard for all? Do you know when the night rate kicks in?

I just checked and it looks like our meter does have a day and night rate, which I guess is good! thanks

@firat your night rate runs between 1 - 8am every day. If you want to pay the same price regardless of when the energy is (called a 1-rate tariff) then let us know. We would say if you use less than 40% of your energy at night, then it might be worth moving to a 1-rate tariff.


@firat your night rate runs between 1 - 8am every day. If you want to pay the same price regardless of when the energy is (called a 1-rate tariff) then let us know. We would say if you use less than 40% of your energy at night, then it might be worth moving to a 1-rate tariff.

Do you mind posting up the cost for the two different versions of the tariff?

I.e. the 1 rate tariff/kw costs (I have the costing for the one I am currently on)

This is so I can work out which is best for me!


@firat The single-rate price is 12.447 pence per kWh in your area. The standing charge remains the same at 24.56 pence per day.

Thanks for that, It appears that I do indeed use alot of energy during the night - so I think I will stcik with the two rates. Thanks!