Octopus Cosy isn't the worst Energy Tariff anymore!
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- Опубліковано 5 лип 2024
- I championed Octopus Tracker and Agile as the best energy tariffs last winter, especially for those with heat pumps.
BUT
Octopus Energy have listened and have amended their Cosy Tariff. It now looks quite attractive and may be the go-to tariff this winter.
This could work well for those with small home battery storage.
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My system :
Vaillant Arotherm Plus 7kW
200L UniStor Cylinder
45L Buffer tank
140sqM Detached 1997 built house
10mm copper microbore pipework downstairs
Installed by British Gas in November 2023
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Another great video to get people thinking. The difficult thing in planning a strategy is that there are no constants. I would advise against anyone making big financial purchases based upon specific energy tariffs that are available at the moment because chances are they will change or be constantly tweaked. As you have championed, the key is to follow the data. Takes all the emotion out of it.
Very true!
It's quite astounding how much smart tariffs have changed in the last 2 years that I've been properly engaging with them.
I'm sure the next 2 years will have the same in store for us.
One of the things I've enjoyed seeing this year is more competition to Octopus from OVO, EDF and the likes.
@@UpsideDownFork
Side note to those with British Gas installs, they appear to be offering a 14p/kWh for heat pump customers, I received an email from them today.
I'm in process of jumping across to them from OVO.
I use the Cosy tariff, with an ASHP and a smallish - 10.4 kwh total, about 8.9kwh usable - home battery (no solar). It worked ok with the double dip, i.e. heat pump run at constant full weather compensation (no overdriving), water heating during the dips, etc. and fairly minimal use of electricity outside the two cheap periods, and no use of the premium period. This last bit was easy as it is immediately preceded by a cheap rate period so I always start the premium period with a 100% full battery. Also note that as my wife and I are both retired, we use the three hour cheap rate period in the early afternoon to run things like the washing machine and tumble dryer. The new three cheap period tariff is even better and I anticipate close to zero use of anything other than the cheapest rate this winter. Cycling the battery 3 times a day is really sweating the asset and means I believe I can run my house with heating/hot water/cooking with no gas purely on cheap rate electricity and a fairly small battery
Looking at this I see 3 opportunities to pretty much recharge a battery during each stage, so even at worst case where you needed to run the ASHP all day you could easily avoid the 3 hours of super high cost and at worst maybe need an hour of expensive energy. Most times it would work very well even with high usage.
For me the 3rd slot would make a huge difference to knowing a battery could cope nicely.
I tried Cosy for a month last winter, but it was working out more expensive, so I went back to Agile. Heat pumps work best left on all the time, not overdriving them in cheap periods as it kills the COP efficiency. It's better just to avoid the peak periods with a set back temp instead.
I plan to go onto this later this year. My battery will be able to recharge 3 times and run my heat pump to heat my hot water. Then run off the battery the rest of the day. Off peak for me on Cosy is 10.5p currently.
Cost efficiency > whole home efficiency > heat pump efficiency (COP).
The latter being of most interest to us nerds, the former being the thing that depends on the whole home and the grid much more than just the heat pump.
@@TheBadoctopus great perspective 👍
I was thinking exactly this ,self install 7kw arotherm has been tested now for hot water, combi has just been removed and ready to switch over. I have 15kwh battery and could make the new cosy work no problem. Only issue is my inverter has only two charge periods. Trying see if there is a workaround for Solax. Keep the videos coming.
Fingers crossed there is a firmware update or something that can give you that functionality.
Otherwise it may be a home assistant integration that can allow you to take that control?
Interesting conclusions. I just ran through looking at modelling my last years consumption based on Octopus Go and Octopus Cosy. For context we have 10kw of solar and 21kwh storage. Based on the figures the Cosy tariff worked out 43% more expensive based on our current usage. It really depends on the setup that is in place to how things work out.
2 great points made there.
1. Do your sums!
2. Those with larger battery systems will benefit from the lower unit rates offered with Go or even Intelligent Go if you have the compatible hardware for that.
I was on Cosy last winter. I thought it was great then, and it’s about to get even better. It wouldn’t make sense to use it without battery storage though.
I wouldn't advocate cycling your batteries up to 3 times a day. The lifespan of most domestic batteries is around 4000 charge-discharge cycles, which would reduce their lifespan to under 4 years if done daily, although we're only really talking about November to February. Octopus Flux doesn't have any impact on number of cycles as you're incentivised to charge once a day from the grid overnight and discharge once a day over the evening peak and would still seem to be the way to go if combining heat pump with solar panels and storage. Even with the Octopus Flux tariff until the end of last month I calculated that there was no business case for increasing battery capacity to ensure I had enough capacity to export 16A from 4-7pm every day and with the differential in price reduced from this month it makes a case for not doing it. The changes do however now incentivise you to charge overnight and export your excess solar from dawn, which I welcome.
I have worked out that the return on investment time for extra battery capacity to support a heat pump for my home is always longer than the 4000 cycles of battery life and the ROI time is minimised if going all-in and upgrading to the maximum configuration supported by my inverter. Paradoxically, my current 3 batteries will suffice for 80% of days, 4 batteries would take it to 94%, 5 to 98%, but it would take the maximum of 7 to get to 100%. Consequently, in practice, most of the ROI would come from evening peak rate export, not from having enough battery storage to run the heat pump most or all of the time. As that price differential is at the mercy of Octopus and nothing to do with the efficiency of my system, it makes it a gamble, not a strategy.
I have also worked out that the changes in Octopus Flux increase my potential saving from installing a heat pump from £185 to £209. Of that, £103 comes from eliminating the standing charge for gas, so the additional saving would be a gamble that the heat pump would work at least as well as my current gas boiler. Again this is a gamble, not a strategy, and the most compelling reason for doing it is to take advantage of the government grant whilst it is still available. I feel this is nonsense. The Tory government showed cowardice with their imposition of price caps on gas that preserve the status quo and do nothing towards achieving net zero. If Labour are to commit to the targets they need to do the maths and lift the price cap on gas in proportion to lowering it on electricity. However, that would hurt those of us who have done the right thing and become net exporters of electricity in pursuit of net zero overall. A more compelling approach might be to raise the price cap on gas and plough the revenues into a more compelling grant for heat pumps, perhaps focused more on the first decade of operation rather than on installation. We need reasons to turn what is currently a gamble into a worthwhile strategy.
This is assuming you are fully depleted the battery. Slightly larger systems like mine would be using in my case 60% . Also most are 6000 cycles and then is degradation not a completely damaged battery.
Wow, totally correct on so many fronts. It will be very hard for any political party to address the changes you highlight because put simply, the country is financially crippled.
A couple of points to consider, good quality Lithium Iron Phosphate batteries now available can last about 10,000 full charge/discharge cycles.
"so the additional saving would be a gamble that the heat pump would work at least as well as my current gas boiler."
There is no gamble, a heat pump will work significantly more efficiently than your gas boiler; gas boiler COP at best is typically 0.85, a worse case scenario for a heat pump SCOP (measured over 12 Months) might be 3.5 (mine is 4.3 over last five months) still making it four times more efficient than a gas boiler in terms of energy consumption.
For reference, many commentators suggest Flux should only be used in the summer, with a switch to Agile or Go (and maybe now Cosy) in the winter.
@@Biggest-hz7ng
Agile changed last December and is now a 12 month contract for new customers
"Updated December 2023:
For new customers, Agile is once again becoming a 12 month fixed term tariff because current regs don’t really work with the dynamic nature of Agile - specifically, without a fixed term the tariff will be subject to the price cap, resulting in unworkable complexity with half-hourly wholesale prices."
Will be moving to cosy over the winter - would have been with just the double dip as I have the Tesla battery. All about planning your use through the day with heavy use items like dishwasher and washing machine. Using them in the cheap periods while charging your battery means I should be able to run my heat pump at a constant temperature utilising the battery in the normal periods.
That's exactly what I do, although, having said that, as long as your machines don't have a heavy draw, you can use them anytime. One of of the joys of Cosy vs Agile is that it's easier to manage - especially with a busy household.
The prices don't match up with the graph from Octopus. They should show square dips rather than trapezoidal ones.
I also feel a desire to be the graph police! They seem to smooth off their graphs in the same way they have a cute octopus.
Annoying I know, but I was too lazy to go ahead and re-do them myself!
I agree, Cosy is now an excellent tariff if you have a battery, I switched from Agile last month and there are a few advantages you didn't mention:
1. Setting regular charge periods mean you don't have to obsess about the rate at the time - Agile Tracker, Flex etc. (And relax!)
2. You stop thinking about 'the best time to use energy'. With 3 cheap charging periods, your battery always has enough in it to deal with virtually any situation.
3. With a few recent exceptions, Agile prices have not been terribly good over the past few months. For me, it's only been cheaper than Cosy once (per bill) in the last 5 months.
4. As your battery is always fed during cheap periods you can pretty much guarantee your average rate will be the low one - unlike Agile.
Highly recommended.
Thanks for highlighting those points.
I guess you don't have solar panels?
@@UpsideDownFork That's right, we can't have them here.
The ROI of a battery is all about how many pence per kWh of storage you can save per day. So if you can use it 3 times a day, the ROI is 3 times higher. If you can save 12p per kWh, that's £131per kWh per year - and the cheaper batteries are now about £200 per kWh. That sounds like a battery would pay for itself very quickly, but your heating demand isn't constant. If you size the battery for the coldest day, you'll probably only average half of that over the winter and barely use it in the summer. That would push the payback period out past the 10 year guarantee period and approach the likely life of the battery.
I think it would be very hard to optimise the size of a battery to match your heat demand, because it's so variable.
OTOH, if you've already got a battery to store solar power overnight in the summer and use it to store cheap over-night power from GO in the winter, it would be worth switching to cozy for the coldest months when one cycle isn't enough to last a day.
That's a great quick way to work out suitability! Thanks for sharing.
Agile might still be a better bet. We can expect almost 4GW of additional wind generation coming on stream this winter which will impact the overnight electricity period. Last winter gas was generating power merely for the kinetic energy to maintain frequency on many a night. This coming winter that gas burn is likely to reduce as more tools to maintain frequency are available from batteries and old generators merely spinning. Over the last few days we see what happens when the wind blows not just in the UK but over Northern Europe. Denmark, Germany, Belgium and the Netherlands all contribute to surplus power.. And whilst batteries are no doubt a useful way of cutting costs, a storage heater might be a cheaper and more useful way to maintain a warm home for folks in well insulated homes.
Moray West offshore wind farm has just come online in past week, with about one third of its 60 turbines operational on National Grid to date. Each capable of generating 14.7 MW.
@@_Dougaldog Dogger Bank A is beginning to get installed at pace that should add 1.2 GW by January, Viking on Shetland is under test to add 450MW, Neart Na Goithe should also add 450 MW by year end Moray West at 850 by January and Dogger B has a big question mark over it. The foundations and transition pieces are going in but the delay on Dogger A is holding back 1.2 GW by 12 months. Sofia at 1.4 GW will be in by Dec 2025... ! Plus a myriad of small on shore schemes. These change the electricity system to one which is mainly renewable from this year on.
Yes, I agree there is lots to look forward to!
I'm probably going to ride out agile as long as I can and probably evaluate on a weekly basis once we get into the proper heating season.
What export is available with cosy?
@@JohnR31415 15p on the Octopus fixed export which is available with cosy. 👍
Would it not just be better to schedule an immersion heater on during the dip periods for hot water?
A heat pump will heat hot water much cheaper than an immersion heater, with a typical COP of 3.5, means that a heat pump will give 3.5kW of heat into Hot Water Cylinder for each 1kW of electricity used.
As a typical example my 6kW Daikin can heat 150 litres of water from cold (@ 10C) to 50C in roughly 55 minutes using just under 2kWh of electricity.
My daily Hot Water average though is about 800Wh to top up tank (about thirty minutes), the money I saved on gas standing charge (31p/day) effectively pays for my hot water and I'm on a standard tariff of 22.89p/kWh (Includes VAT) :-)
@_Dougaldog Indeed, but in the context of the first scenario, being able to schedule an immersion heater to come on in parallel with the heating would work. It's not always about the money/efficency. Interesting to note that Heat Pumps can't do heating and hot water at the same time, but boilers can!
@@edwardpickering9006
You said, "Interesting to note that Heat Pumps can't do heating and hot water at the same time, but boilers can!"
That is not correct, a gas combination boiler does not do hot water and heating simultaneously, it has a heat exchanger for hot water that it diverts flow to instead of radiators.
My Mixergy HWC is capable of reacting precisely to the Octopus Agile tariff (programmed into it's Raspberry Pi controller) and use Heat Pump as primary heat source.
Although not the ideal in terms of efficiency, I guess it's a strategy that could work in some cases.
Good job thinking outside the box!
@@_Dougaldog I wasn't talking about a gas combi bolier, our system boiler installed in our new build can do both at the same time.