Saving sessions

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[XAP]Bob
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Saving sessions

Post by [XAP]Bob »

This winter the National Grid trialled domestic demand management to reduce the need to warm up our least efficient power stations.
The energy market works on half hour "settlement periods", and the target is to reduce the peak load in the highest of those sessions, moving that energy usage either before or after the session, where the grid load isn't as high.

They've done this by offering to pay customers (via their energy retailer) for reducing the amount of energy used in two or more half hour periods - Octopus have called these periods "saving sessions", so that's the terminology I'm using here.

So for a weekday session (and they've all been weekdays, as opposed to weekend/bank holiday sessions) you take the average load during the previous ten weekdays which haven't themselves had a saving session.
So if you normally use 1kW throughout the day (unrealistic, but easy) then each settlement period has 500Wh on average.
If you turn off everything (i.e. go to zero watt) for a one hour session then you'll save 500Wh in the first period and 500Wh in the second, and therefore get paid accordingly.
You can use that energy in advance (turn the heating up a bit earlier, and let the house act as a thermal battery - cook before the session) or after (reheat the house, cook later), and that's the point of the session - some of that peak is spread out across the day, making the grid peak load lower.

However, there is an "In Day Adjustment" applied as well - and this is horribly broken.
Basically they tried to account for people with electric heating having to run more on colder days, so they take six settlement periods ending one hour before the session and compare those with the last ten days as well.

This is then used as an adjustment to your savings, so if you use an additional 1kW for those three hours then you get charged for 3kWh at peak rates, however you are then deemed to have saved an additional 500Wh per settlement period during the session.
Ok, that's a 6:1 payback, that can't be good right...

Today's session is valued at £3 per kWh saved.

So our hypothetical household with constant 1kW usage could save 1kWh for £3.
OR they could spend 35p*3 = £1.15 by using extra in advance and that generates a "saving" of 1kWh, giving a profit of £1.85 - or a cost per kWh used of negative 62p.
OR of course they could do both...

With solar panels and a battery my previous ten days average consumption has been 87Wh across the two periods (basically just battery response time jitters).
But my IDA period has also had an average of 22Wh - so I can top up the battery, the car, the storage heater, etc. in the three hours before the session - despite the potential profit I cannot bring myself to turn off the solar panels for those three hours, it rather defeats the point of the session if I'm withdrawing energy from the grid, but I'm ok with load shifting into that "peak, but perversely negatively priced" region.

I have written to them to point out that they really need to fix this for next year, I have no idea whether or not they will.

Has anyone else been enjoying these sessions?
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.
rjb
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Re: Saving sessions

Post by rjb »

I would have liked to join the scheme but BG only invited selected customers to join in. My daughter has used it and saved a few £'s. It's not a well thought out scheme as those most likely to benefit are high users of electric at peak times who can reduce their consumption. Electric car vehicle charging springs to mind. So of greatest benefit to the more affluent society.
I read that they were having issues with the smart data system which prevented them offering the scheme recently which explains why they had coal plants on standby to cope with demand.
At the last count:- Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin X3, Raleigh 20 stowaway, 1965 Moulton deluxe, Falcon K2 MTB dropped bar tourer, Rudge Bi frame folder, Longstaff trike conversion on a Giant XTC 840 :D
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[XAP]Bob
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Re: Saving sessions

Post by [XAP]Bob »

British Gas might have had issues with the data, but Octopus haven't had any widespread issues to my knowledge. I do download my usage daily, and have rather comprehensive spreadsheet running with the data. :mrgreen:

Of course those who use more at peak times can benefit more - that's inevitable, they can make the most difference to the peak and so arguably should benefit most. But I imagine that most EV owners already use a time of day tariff and already shift their EV charging to off peak hours, it makes a significant difference - even accounting for the higher peak rate (Pre battery my average kWh rate (including the standing charge) was 25p last year despite my peak rate being just under 40p, this year it's under 11p).

The real kicker is that those of us who can afford battery systems etc... can game the savings massively - top the battery up before the session and that usage (divided by three) gets counted as a "saving" when it's really not.
And that's what I'd rather they fixed, not the "high user gets more reward" which is an inevitable result of them being able to do more.
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.
briansnail
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Re: Saving sessions

Post by briansnail »

Solar panels were mentioned.I do not want to put on the roof .My garden fences on one side capture a lot of sunlight.Does anyone know if its feasible to put approx 5 solar panel at a slight tilt next to a sun facing fence? and is it less efficient to a roof mount?
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Jdsk
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Re: Saving sessions

Post by Jdsk »

briansnail wrote: 24 Mar 2023, 4:10pm Solar panels were mentioned.I do not want to put on the roof .My garden fences on one side capture a lot of sunlight.Does anyone know if its feasible to put approx 5 solar panel at a slight tilt next to a sun facing fence? and is it less efficient to a roof mount?
If the angle to the sun is the same and they won't be shadowed then it's not less efficient.

You need to think about the safety if they're more accessible to children, animals etc.

You might need planning permission.

And of course you lose the space on the ground... unless you can think of something clever to put under them.

Jonathan
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[XAP]Bob
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Re: Saving sessions

Post by [XAP]Bob »

briansnail wrote: 24 Mar 2023, 4:10pm Solar panels were mentioned.I do not want to put on the roof .My garden fences on one side capture a lot of sunlight.Does anyone know if its feasible to put approx 5 solar panel at a slight tilt next to a sun facing fence? and is it less efficient to a roof mount?
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I ride Brompton and a 100% British Vintage
Define " a slight tilt"

If you mean from the vertical then they'll not do very well - you ideally want them perpendicular to the sun (I mean ideally you'd want them tracking the sun, but that additional complexity is not justified). If they're near vertical then even in winter they'll be a long way off well angled and in summer they'll be almost shading themselves.

Ground mounting panels is a valid option, though it's not a particularly common one for such a small array.
Any particular reason you don't want to put them on a roof?
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.
francovendee
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Re: Saving sessions

Post by francovendee »

[XAP]Bob wrote: 24 Mar 2023, 8:41pm
briansnail wrote: 24 Mar 2023, 4:10pm Solar panels were mentioned.I do not want to put on the roof .My garden fences on one side capture a lot of sunlight.Does anyone know if its feasible to put approx 5 solar panel at a slight tilt next to a sun facing fence? and is it less efficient to a roof mount?
*******************************
I ride Brompton and a 100% British Vintage
Define " a slight tilt"

If you mean from the vertical then they'll not do very well - you ideally want them perpendicular to the sun (I mean ideally you'd want them tracking the sun, but that additional complexity is not justified). If they're near vertical then even in winter they'll be a long way off well angled and in summer they'll be almost shading themselves.

Ground mounting panels is a valid option, though it's not a particularly common one for such a small array.
Any particular reason you don't want to put them on a roof?
All but one installation of solar panels around here are on the roof; large farm buildings to houses but one metal fabricators has three large panels that tilt and turn in there grounds. Lots to go wrong and a bit of an eyesore but it's on an industrial estate so not spoiling the landscape.
Here the solar panels replace the tiles whereas in the UK I think they cover the underlying tiled roof. I think I prefer the UK way.
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[XAP]Bob
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Re: Saving sessions

Post by [XAP]Bob »

We do both in the UK - my parents had a new roof (and cornish winds) so went for flush mounted panels, I have rail mounted panels.

Tilt/turn is generally too complex to be worth it, and the pitch of a roof is usually "close enough" to good to be practically useful.

The advantage to a ground mounted set up is that you could manually change the pitch through the year - I still think that the roof mounted option is much simpler.
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.
rjb
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Re: Saving sessions

Post by rjb »

My daughter has made use of the schemes. BG are doubling or tripeling the saving. She has saved approx £20 over all the events. She's quite canny. Offers the savings to her children to put in their money boxes. They run around the house turning off everything and in the process learn to be energy efficient :lol:
At the last count:- Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin X3, Raleigh 20 stowaway, 1965 Moulton deluxe, Falcon K2 MTB dropped bar tourer, Rudge Bi frame folder, Longstaff trike conversion on a Giant XTC 840 :D
pete75
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Re: Saving sessions

Post by pete75 »

The big advantage of solar panels is the subsidy. We get about £1800 per annum in feed in tariff.
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rjb
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Re: Saving sessions

Post by rjb »

Not any more. The Fit scheme is dead. Closed in 2019 to new generator's. The current SEG scheme which replaced it is not as generous.
Read what Which say's about it.
https://www.which.co.uk/reviews/solar-p ... 2wh8b519s2
At the last count:- Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin X3, Raleigh 20 stowaway, 1965 Moulton deluxe, Falcon K2 MTB dropped bar tourer, Rudge Bi frame folder, Longstaff trike conversion on a Giant XTC 840 :D
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[XAP]Bob
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Re: Saving sessions

Post by [XAP]Bob »

Other options are available... we're currently running at (ignoring saving session days, because they're just weird) over 90% self consumption - with much of the export happening whilst we've been away - and 87% of my electricity imports are off-peak, i.e. cheap rate.
Octopus Agile and Flux both have far better export rates, but you do need to be a little savvy about how you use them - and have a large enough system to benefit.

I am targeting the vast majority of my generation being self consumed, because there is so little incentive to export.
I just added another Tasmota relay to my car charger to drop it to 16A, rather than 32A, so that I can automate enabling it during the day when the battery is topped up and the sun is shining, then it will turn off when the battery drops a bit, or if the solar output really drops. (I'd love to get a solar aware charger, but I'm doing what I can myself).
That should give me significantly more self consumption in the summer months which are coming (I'm also starting to turn down the "charge to" level for the overnight charge, so that more of the day is spent charging the battery rather than exporting).

My current calculation on the latest saving session is that I made ~£18 (accounting for the peak energy used).
The last one was *very* short notice, but the one before that I made ~£7, which gives me confidence in my calculations.

The effect is that overall this year I have paid, including the standing charge, ~9.6p/kWh. That's slightly optimistic accounting - if you include a charge for the PV/battery (assuming 5 year depreciation) then it goes up to 31p/kWh, which is still ~10% under the price cap (which excludes the standing charge) - and of course it's for three pretty dull months of the year, I expect the next six months to be substantially cheaper. Pick your depreciation period to move the current cost anywhere between 10p and 30p.


"BG are doubling or tripeling the saving." Are they? Or are they simply bidding high and getting accepted?
The payback for the different sessions has been different, because of the way the savings are bid for (it's bizarrely complex behind the scenes)
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.
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