Octopus Saving Session

Again 24th March, East Midlands, 6-7 this evening. The reward is 10% greater today.

Roy

How much are they paying?
I've not heard anything about it

Marren2016 102 Octopoints equal to 14p/kW saved.

Roy124 12.75p/kWh (divide the points by 8, cuz, you know, Octopus).

I see, it's regional? And we need to install a new app?

TX200 my error, certainly came to the correct value, must have had a BF

yeah I had the saving session (Bedfordshire). Predbat exported a bit in the last 20 minutes, but TBH its not worth it

PredBat exported more than it planned to. Down to 21% rather than 28%

Probably going to run out of battery before the off peak starts.

Was it worth it, probably not. 🤦😁

I was monitoring my system during the period. The battery percentage stayed at 100% with no grid input. Octopus showed minimal consumption. Then iit suddenly caught up

TX200 I worked out it costs £2 per charge/discharge cycle of the battery (£6000 ÷ 3000 charges) so unless I can earn more than £2 its not worth the wear and tear. And the issues I've had in the past have been after exporting at full power.
I think with octopus reducing the FIT to 12p i might just look after myself from now on. Import has increased and export has decreased. And then they want to take charge of your storage for the grid.
My system will never pay for itself so why should I support the grid, they've put the middle finger up to me.
If everyone chose to do this and show the energy companies who's boss they would pay us more.

Communitarianism for us, profits for the fat cats.

Marren2016 I'm not sure I agree with your logic of cost per charge/discharge cycle.

Yes you may take a view that your battery can "last" for 3000 cycles, so with a £6000 battery cost (I assume an AIO), that's £2 per cycle of amortised cost. The 3000 cycles is a guess?

But a battery is not like a car, there isn't much of a practical second hand market and it doesn't depreciate with use. A battery with 1000 cycles isn't worth more than a battery with 2000 cycles on it and there is no value in preserving cycles.

Rather (struggling to think of the right analogy), you have paid the capital cost of your battery, now is a question of whether you use it or not. If you don't use it, you have gained no value from the £6000 invested and you certainly won't recoup your initial investment.
If you have an AIO, discharge 6kWh at 25p (DFS rate + export rate), refill overnight at 10p (allowing for conversion losses in and out), then you've made 15p/kWh, so 90p. Not going to set the world alight but its 90p more than you had if you didn't use the battery.

I have a 9.5kWh and a 5.2kWh battery. These will last me a day in the summer but in the winter get cycled 2-3 times a day as I have a heat pump and am on Octopus Cosy. The 5.2 battery has done 1700 cycles in 3 years, the 9.5 has done 1100 cycles in a year and a half. I work out my payback based on what my consumption would cost if I wasn't on a smart tariff, and am on track to recoup the investment in 7 years, but that's by using the battery and not worrying too much about the usage,

Agree with @geoffreycoan - I think the best way to use a battery is fill it up every night from off peak rate and empty it before the end of the day.

Get the most out of the investment.

(Perhaps even fill it up twice a day, sunny days!).

I'm on octopus agile, charging up over night would be stupid as currently it's 25p cheapest (because of Donald trump). My point was that it's not worth selling energy to the grid when all you're doing is breaking even if they automatically charge the battery at expensive prices. Factor in the charge cycle and you're at a loss.
I have a 9.5kw gen 2 bought in lockdown.

Buy a compatible EV go to IOG and the off peak is 5.2p, then export excess at 12p. Works for me plus the car is running around at less than 2p a mile.

SimonClarke but how does that work with a heat pump?

Marren2016 because of Donald trump Netanyahu/Israel

FYP 🙂

Vestas still we have North Sea oil and capacity for gas storage.

Roy124 works fine. Our total energy bill last year was around £200. EV doing 10k, heatpump doing all heating and dhw, house at 21c throughout, all electric house, with 6.24 of panels, 9.5 battery and gen 1 5kw inverter. Load shift major appliances. 90’s Persimmon 3 bed bungalow which had a EPC before the heatpump of B. 2 elderly occupants! No HA or any other fancy controls but I did just fork out for Rubikcubes app just in case.

Roy124 That's actually very funny. I have a bridge to sell you as well if you think Brent crude is going to help - and the Rough storage facility is once again closed because the govt won't pay for it.

@SimonClarke just goes to show, battery more significant than panels. I used the same supplier as my brother in law, mistake in a way as they went belly up. Fortunately I accepted an offer of the 5.25 battery over 3.6.

It really is a shame that information from forums such as this only become available after purchase unless a friend points you here.

Roy124 some of the coldest days the battery ran out by 10/11am but that's only a few days a year. Most days in the winter we got to run off the current 7p stuff either directly from 23.30 to 05.30 then battery juice until sometime pm leaving only the last third of the day at full price and if the sun comes out even better. The heat pump rarely seems to use more than 2kw so if careful during the day we can avoid drawing from the grid but to be honest we don't worry. Used to spend at least £650 on oil alone at the old price.

SimonClarke As always individual mileage will vary.

Sounds like you have a well insulated house, EPC B and heat pump not pulling more than 2kW. Mine is a C and the heat pump will draw 3-4.5kW so good job I have two inverters and two batteries that can keep up with that load. This winter I changed the heating controls to turn the heat pump off for the hour or so that we are typically cooking, and this has made quite a difference in avoiding peak rate imports.

For me more solar panels is more important than batteries, I can generate sufficient in the summer to build up a credit for the winter that means an annual bill of around zero. Last year was -£100, we shall see this year with the rate changes.
Batteries can become diminishing returns, As long as you have some batteries to see you through an evening peak, or at least most of the evening peak, that's really all you need. It comes down to blended rate and spending a few thousand to save 20p/kWh on day/peak rate import is a hard justification to make. Also the inverter throughput can become the limiting factor, I have to set a reserve on my 9.5 during the day of 34% to ensure that I don't drain it too much and can't charge it back to 100% in the 3 hour Cosy periods. For the evening peak I set the reserve back to 4% to use the whole capacity.

Our heatpump consumption is considerably higher but then we keep our home much warmer than many. Over the year £130/month is a lot less than before. Previously we had a gas boiler with a very hard to see pressure gauge and not infrequent shutdowns. They were particularly annoying to wake up to cold water and no heat especially if we were away.

Roy124 we found the simplest way to be comfortable was to run the heatpump continuously at the same temperature. Once the fabric of the house is warmed up we have even turned it down a degree as it was getting too warm. I did play around with the weather compensation to start with but haven’t touched it for months. In an ideal world some more panels and another battery would be good but not economic. Instead we have gone for triple glazing but mainly because the original windows were old and my other half hates them! Hopefully it might save us the £200! Not really economic….

geoffreycoan I suspect that your "summer credit" will drop very rapidly in the next 5 years so enjoy it while it lasts.

There's a quite staggering amount of commercial PV coming on-line VERY rapidly and I suspect that people will be lucky to get 3p/unit for export by 2030 - unless they have a battery and hand over complete control of their system to a supplier/third-party.

I expect "normal" daytime export (ie direct/uncontrolled from PV) will be actively discouraged via pricing/tariffs within the next 3 years, indeed you could argue that's already beginning to happen on Octopus.

I suspect there will be an awful lot of (richer) people whinging because they installed far more PV than they could use in the expectations that they'd continue to get effectively free electricity over the course of a year. Where we are now in terms of pricing doesn't last in ANY other country which has been deploying domestic PV for decades. There's a well-trodden path we're following - look at California and South Australia for example.

Anyone buying PV panels now and using current export rates to justify PV array outputs they can't possibly utilise is in for a nasty shock.

SimonClarke we need to vary our settings as SWMBO prefers 23 which is too hot overnight. Drop it to 19 overnight and also a couple of degrees at peak time.

Going away during the winter I drop 18 before increasing the day before returning.

Vestas
Good thread - very instructive. If I may add something. I have a two bed bungalow (in South Wales) extended into garden. Our Solar system was fitted in October 2024. It is E-W and so have two arrays - absolute max we generate when sunny in M-J-July is about 7-7.5kW..mostly max is around 6kW. I have a G3 5kW hybrid inverter with two 5.12kWH Gen 1 batteries and recently added a 5.14kWh Gen 3 battery. (Had to fight to get a local installer who would deal with GE - called >8 companies). We had a (ASHP) heat pump (LG Therma V 7kW - the 7 means the max output from the pump. It uses between 2kW-3.5kW energy depending on outside temperature) installed during the renovation before we moved in in 2023. No gas used in the house at all - Octopus removed the gas meter as well - so no daily charge for gas.
The ASHP was costly in terms of energy which is why we decided to get solar (and for environmental reasons - naturally...but hope that "Phoenix" fella has left our community! - if you know you know -))
Bill for Jan-Feb 2024 was £220 - for same time 2026 was £100. We made on Flux last year (2025) about £700 - so it almost have covered us over Oct-March.
We have been using Cosy (Octopus tariff for heat pumps) over winter because its three cheap periods totalling 8h at 14p/kWh. We never actually needed to charge up for the 8h.
Also Our LG has weather compensation (called AI by LG) and it was not properly set up and so I fiddled a bit and now it works well. The heating automatically goes off when external temperature reaches about 16oC - only happened once this year!. We keep the bungalow around 20-21oC during day and 19oC at night...so "cosy".
We do not (yet) have an EV.
Like many here I am waiting to see what Octopus do regarding export payments for Flux and/or Octopus Intelligent Flux. Still it may be worth paying the Cosy £50 exit fee to move to it.
I purchased a cheap Android tablet from Aliexpress (China) for about £34 all-in on which I have installed the full RubikCube Inverter app - many thanks to him for setting this up app responding to queries so rapidly - very public-spirited!!. I read I can use a VPN to access it from outside home and so if the portal goes we have something that is so useful.
I want to thank so many people in this community who support others with help and advice - it is so welcome.
Anyway - my submission FWIW

Pretty sure we could just drop-in a heatpump without any other work. Gas boiler has weather compensation and I set the curve so its at 40C or under on the rads. That keeps most of the house about 20C without running it all the time - and pretty much not at all if its 9C or above outside.

House (new-build 2022) is EPC B but is going to be more like A after I filled in the gaps the electricians left/created. Plumbers - no problem, they fill in gaps, sparkies are clueless. If they did the air tightness test (new-builds) now it'd be 75% better.

Still don't see any reason to fit one - not while we're still burning gas to generate electricity to generate domestic heat.

Also of course there's the spark-gap on gas-electric pricing which is entirely political - it'd be a brave/lunatic party who would quadruple the average poor(er) family's heat/water bill while simultaneously giving grants to rich(er) families to reduce theirs. Someone is going to have to bite the bullet on that one and the very best of luck to them.

AndyZ900rs As much as it might sound like I'm a sceptic - I'm not.

I just think there's a huge amount of misselling going on. I think people are buying into systems they don't understand/need or (increasingly) control on the basis that current export pricing levels will continue. They won't.

This WILL lead to people being preyed upon by dodgy "balancing/VPP" companies offering gold somewhere over the rainbow if you let them take control. The whole DFS/balancing scheme lends itself to cowboys now and as usual the PAYE taxpayer will have to bail out the rich when it goes tits-up (as it will).

Self-consumption should be the mantra for PV+heatpump installs - ie install what you need plus 25% for future needs.

Vestas House (new-build 2022) is EPC B but is going to be more like A after I filled in the gaps the electricians left/created. Plumbers - no problem, they fill in gaps, sparkies are clueless. If they did the air tightness test (new-builds) now it'd be 75% better.

I wonder what effect ASHPs have on EPC. Rumour is they have a negative effect. Regarding leak stops, dont hold your breath. The EPC is perfunctory at best. Our last home was built in 1974 - date was imprinted on a brick. Not good enough for our man. The house did 'not' have cavity insulation as it was 1970s and there were no drill holes in the wall.

We told him that there was as we saw it when we had work done - not acceptable. I showed him additional cladding on the exposed garage wall and inside a bedroom. Again ignored.

I agree with the direction we are going towards with export tariffs dropping and encouraging people to only export in the peak rate when the grid needs it. As you say, California and Australia are good examples of where this is already in place. I’ve seen the Flux day rate drop from being quite attractive to being less than the flat rate export, and doubtless more to come.

I got the solar principally for self-consumption, and had had it for 6 months before I moved to a smart tariff (Flux) and had to relinquish the FIT deemed export payments for my older FIT array. I asked for as many panels to be fitted as possible figuring that since I was paying for the scaffold I might as well use it, and panels are relatively inexpensive.

I have a similar LG heat pump to @AndyZ900rs, only mine is the 9kW model, and I have two of them for the heating. Weather compensation/AI wasn’t even turned on on my setup, so the early electricity bills with a 52 degrees flow rate were awful, Over time and with tuning I’ve got the consumption and £ down to half what it initially was, and less than the oil boiler it replaced. House comfortably warm all the time with 19 degrees as daytime temp and 18.5 overnight.
I now use one heat pump for water and one for heating so this keeps the peak power draw within my inverter capacity.

@Vestas your post seems an appropriate place to drop in a thought i had for new business proposition. As homes become i increasingly Smart there will be a need for education when sold.

There could be an opportunity for Smart Home Management. For instance I have a burglar alarm that is connected. I have Smart power sockets controlled through Alexa. My central heating system has individual programmable thermostats. The heating is ASHP. There are solar panels, battery etc.

When we sell, knowledge i have acquired during years of occupation will have to be imparted with a quick brief and a stack of instructions.

If I could employ a Smart Home Manager I could offer this as part of the deal.

Roy124 This is a new-build so I know the original air-leak test result and I know how they eventually got it to pass. Lots of silicon under skirting boards.

Basically the whole problem is that the sparkies put the consumer unit in the wrong place so the wiring ran through an uninsulated space over an integral garage canopy rather than into the insulated house space as designed.

So they drilled a large hole through the wall into the insulated space above the steel support to route wiring and left it open. This caused cold air to flow into the ceiling space between the ground and first floors in winter and hot air in summer. I fixed it myself rather than have them tell me it "passed the tests"....

geoffreycoan You have the space to install more batteries/future batteries so you can always increase self-consumption. Most can't and having seen a 9kW PV install on an identical house to ours down the road you have to wonder what they're being sold?

Roy124 why do you have programmable stats? We have stats that were here before ashp but they are all wide open. As I said the whole house is the same temperature - about 21 - and pretty much stays there whatever is happening outside. Got round the too hot at night thing by having less bed clothes. Definitely no duvet! Both of us are completely used to it now. So glad I didn’t go with the ASHP companies that wanted to rip out our 10mm pipe that is in the walls. It would have been completely unnecessary. Scop is currently 4.4 after 18 months.
If they stop paying for export then another battery might become more attractive but even without it the cost will still be less than the oil even at the pre orange blob fart in Iran prices.

Wow - lots more to think about. Our 15+kWh battery set up is sufficient for our use I am sure. I agree with the EPC evaluations - done more for selling houses than anything - and you are correct in that there are cowboys all over the place. Some seem to spend a few minutes and some an hour and review all paperwork. We used to own houses for rent and we "knew" who we could ask...
As regards export rates - In the end I am not too fussed with lower rates if we can get our bill down to close to <£200/pa (at current rates) then that is fine.
What I notice is that if you already have ASHP and want to install solar+batteries that some installers have absolutely no experience of how much energy they use and some ignore whether you have gas boilers as well. There ought to be more certification and regulation. I know WHICH have some experience in this area and give advice but there are so many Solar Installers who have cropped up in the past couple of years who know nothing...many from being UPVc window installers to roofers and scaffolders with access to electricians. It is not the actual building work but the attention to all the details mentioned in this thread

Vestas Still don't see any reason to fit one - not while we're still burning gas to generate electricity to generate domestic heat.

If a power station is 40% efficient at turning gas into electricity, then a hp only needs to be cop 2.5 to get you back up to 100%

AndyZ900rs I wouldn't actually expect PV installers to have expertise in heatpumps and frankly from what I've read here & elsewhere, even competence in heatpump install seems to be pretty rare.

A decent analogy as to where we are would be the early days of double glazing, before the govt had to legislate for insurance-backed guarantees after all the failures/phoenix companies. Rinse & repeat with insulation grants and cowboys. Etc etc.

DD a gas boiler is cheaper to run than a hp at 2.5cop. and I'd imagine the emissions are way lower than a 40% turbine

DD Indeed but its still not a reason to rip out a 4 year old boiler. In terms of carbon cost I'm never going to recover the cost of the battery system, the inverter will take 6 years and the PV panels - no idea.

On the subject of EPC's and the quality of them, I can recommend Michael Podesta's blog https://protonsforbreakfast.wordpress.com/

He is way more nerdy on his energy analysis than pretty much anyone else I know, and writes some interesting articles. There's a series of article about his EPC about 6 months ago.
In short, he was I think B rated, had over the years had energy improvements done to the house, decided to get a new rating and it came back as a C rating which he was quite surprised about. A lot of the EPC is based on assumptions from the surveyor, the oversight organisation basically doesn't care and he demonstrates how its a wild west of results.
Another company redid the survey, taking far more time over it, and got an A rating.

SimonClarke why do you have programmable stats? We have stats that were here before ashp but they are all wide open. As I said the whole house is the same temperature - about 21 - and pretty much stays there whatever is happening outside
Agreed, that's the best way to use a heat pump, it took me a while to learn and convince myself of how they operate differently from a gas or oil boiler, you basically open all the TRV's and reduce flow through the lockshield valves until you get the desired temperature, starting from the furthest rad from the heat pump. Smart stats are no use and will actually reduce heat pump efficiency, you want the whole house fabric to reach the desired temperature.
Good articles on this on the heat geek website

Marren2016 Sure, but the specific reason was that gas was being burned to produce the electricity. There are plenty of perfectly valid reasons for not adopting a heat pump.

Vestas agreed

DD but with solar...makes sense

geoffreycoan Even for gas fired systems my advice would be much the same - assuming well-insulated houses, TRVs are largely pointless.

I run our boiler on a weather compensation curve which hits 50C at 0C outside. Most of the time the rads are at 35-45C.

I did run it 24/7 for a while at 35C(ish) on the curve and the house was a bit too warm in a couple of rooms so likely never balanced.

Interesting...there are a lot of "geeks" here on this chat (probably many Retired) that invest a lot of time (and some money) investigating all this....bottom line most people do not and seemingly most politicians do not...thank goodness we share as honestly as possible our experiences. Too much political short-termism is a major issue. THERE ARE NO SIMPLE SOLUTIONS..sorry about caps lack

I am retired now ( 4 years) i was the London managing partner of a large consulting engineers. We used to offer EPCs and they would be about £750 for a reasonably sized commercial building. The team that did them would "build" a 3d dynamic thermal model of the premises and run it for a year of results. The engineers would also check out the MEP installations and we would issue an EPC certificate. After a while people would offer them for about £200 which we could not compete with. We discovered the simple approach. "Dont go and look at the building and just put in default Building Regulation U values" and do a survey "using Google Earth". These EPCs were frankly rubbish. One of our long term clients asked our advice for a friend of his who had a restaurant EPC that was terrible because of the amount of cooling needed. The "assessor" did not notice the 5m overhang of 14 story tower above it that provided almost full year round solar shading. Pay peanuts, get monkeys.

Roy124 but how does [IOG] work with a heat pump?

Similar story to others on here: I have 6.4kWp solar, 9.5kWh battery, 5kW inverter, 9kW HP and (low mileage) EV, on IOG.
For Jan/Feb, about 25% of import was peak rate, giving an average unit rate of around 12.75p/kWh, which is still cheaper than Cosy off-peak rate, I think. December was about 15%, and other months are negligble.
(Last year, peak import was a rather higher fraction, but that was my first winter with the heat pump, and weather curve almost certainly wasn't tuned correctly.)

AndyZ900rs I'm tending towards the "There are no solutions" stage myself. I think that's the mentality that's driving the wars lately - old men and the planet is screwed etc.

If I take comfort from one thing its China, who having industrialised faster than any nation ever, are now "decarbonising" their industry in the same way. All within 70 years. It can be done.

@SimonClarke "why do you have programmable stats? We have stats that were here before ashp but they are all wide open"

Ten year old Heatmiser system. Each room (10) has its own thermostat. Each permits 6 time settings from Wake to Sleep for each day and individual temp settings for each slot. Frankly PITA as each has its own clock.

The system is divided with an upstairs and downstairs manifold fed from the ASHP. The more modern version can have. Wifi/App control. Highly sophisticated but not the simplest system.

The ASHP allows 7 days and I think 4 time slots with individual temp settings. I imagine the WiFi system is similar and easier. The. Daikin could also accept individual room control.

While I can set individual room temps and SWMBO may tweak the living room to 24 i have control through the Daikin which delivers hott water to the two manifolds 23 in the evening, 21 during the peak period and 19 at night. These are the maximum that the rooms can get regardless of their thermostat settings.

Vestas agree though you may not like their work ethic if you were a worker there.

Could be an interesting economic model in the future. They produce everything to high standard and low cost. We become a consumer society depending on their manufacture society. Weak point, we don't work, we have no money to buy their goods.

Roy124 I think whatever human rights abuses are going on in China will pale into insignificance if all govts don't decarbonise at a similar rate (which they won't).

Deaths from heat/lack of water/starvation will run into the billions - and we'll be part of those casualties when AMOC (gulf stream) shuts down (which it likely will). Pretty much everyone in the UK will die - either from cold or starvation. We don't grow enough food now or produce enough energy to heat buildings so imagine what happens when the average temperature drops by 20C. For those who don't look closely at maps - we're north of everywhere in the USA bar Alaska, we're north of Nova Scotia, in fact we're pretty much at the same latitude as Newfoundland & Labrador where average January temperatures range from -1C to -16C with some bracing excursions to -25C.

Not a lot the individual can do when the Israeli/USA attack on Iran has created nearly as much emissions as Belgium/Netherlands emit in a year.

Its all rather going to hell in a handbasket really 🙁

Vestas if governments were serious about climate change they wouldn't start wars.

Man made climate change is a racket and loads of people are getting rich.

Marren2016 something I wondered about WW2 with thousands of coall polluting ships, petrol guzzling aircraft and many other CO2 events.

I asked my tutor about this "interesting observation"

Personally I believe planet Earth is infinity adaptable with far more impact than we mere mortals can manage.

We already have organisms that can thrive on plastics or oil.

Marren2016 Man made climate change is a racket and loads of people are getting rich.

You're a moron.

Vestas
Harsh but fair. 🤣

In your opinion.

Hand bags please

The phoenix effect...

SimonClarke no, it's Standard now. They changed the name this month

Do you mean the antichrist who comes proclaiming to save the world, and it will all be lies.

https://www.youtube.com/watch?v=LmmmgiPha_Y

SimonClarke Not The Phoenix!!! aaargh...where is he?? drowning in his obsessions...

At 1503 new saving session 27 March 6-7 in East Midlands.

The largest we have saved was 0.75kW. On the 20th March 0.26kW.

I think we are generally either low consumers at these times or have a steady ASHP usage.

Roy124 Potentially you could turn your heat pump off for the hour, and if you have enough spare battery capacity to see you through to the next charging period, export some energy. But at 11.6p/kWh plus your (12p?) export rate, its not going to make you rich

Given the conditions at the time, good light, warm house, i don't think demand was there.
This is my current consumption on the mini

I think PredBat had my attitude to saving sessions now. It's not worth it. It's not doing anything tonight. 😁

Well that's blown it, SWMBO has just switched the oven for supper.

TX200 I think PredBat had my attitude to saving sessions now. It's not worth it. It's not doing anything tonight.

predbat initially decided it didn't want to do anything for me either

then a while later it decided on a tiny export

then it decided it would export across the two slots

it actually exported for 20 minutes, then a bit later another 2 minutes, then a gap, then 15 minutes. So 37 minutes in total for 2.95kWh

my batteries ran out at 21:52, just 8 minutes before the start of the Cosy cheap rate period, so I reckon that was pretty good estimating by Predbat. Would have preferred 8 minutes the other way but I can live with the 0.4kWh grid imported in that time period. Should have turned the heat pump off!

geoffreycoan yeah mine changed it's mind too

It did about 15 minutes, then it said it went back to demand mode (but it was pulling from the grid as it was really in timed export mode and it was outside the timed export window), so who knows if I'll get any cash this time.

I'm tempted to turn off the auto opt into saving sessions blueprint.