Octopus Cosy - new tariff for ASHP owners

[willy_eckerslyke]

OK, I have now run the numbers on our downloaded Octopus data from mid summer when PV was installed to mid winter and simply doubled the answers to get figures for a year.  For us Octopus Intelligent would be cheaper by around £150/yr, but when the better rate for solar export is factored in, Octopus Cosy is cheaper by around £450/year but 'your mileage may vary'. [Octopus pay 4.1p/kWh on Intelligent/GO and 15p/kWh on Cosy].

 

In order to enable some comparisons - we have a south facing PV array, and we use around 4500 kWh/yr and export around 6000 kWh/yr, work from home using around 6000 kWh/yr in the house, have a heat pump using around 8500 kWh/yr and an ev using around 4500 kWh/year.  We do not have a battery or solar diverter.

 

Hope this helps.

[PhilT]

3 hours ago, willy_eckerslyke said:

OK, I have now run the numbers on our downloaded Octopus data from mid summer when PV was installed to mid winter and simply doubled the answers to get figures for a year.  For us Octopus Intelligent would be cheaper by around £150/yr, but when the better rate for solar export is factored in, Octopus Cosy is cheaper by around £450/year but 'your mileage may vary'. [Octopus pay 4.1p/kWh on Intelligent/GO and 15p/kWh on Cosy].

 

In order to enable some comparisons - we have a south facing PV array, and we use around 4500 kWh/yr and export around 6000 kWh/yr, work from home using around 6000 kWh/yr in the house, have a heat pump using around 8500 kWh/yr and an ev using around 4500 kWh/year.  We do not have a battery or solar diverter.

 

Hope this helps.

I've been on Cosy since it started and my average electricity rate is working out c. 13% lower, equivalent to £300pa. I have radiators with my heat pump so can automate a tolerable daily heating/cooling pattern to fit the cheap rate periods. A battery may offer some interesting further potential given there are two three-hour mains charge opportunities at the lower rate, spread a good few hours apart.

[Tomr182]

I think this can work quite well.  
 

I’ve got a 6kw PV, 5kw ASHP and 6kwh battery. 
 

In the cheap periods, heat the DHW and bring the house to desired temp (or a little over in the afternoon) and drop the thermostat a degree in the higher and certainly peak periods so you don’t do much space heating. 
Charge battery to 70% on morning (assume you’ll store some when the sun comes up but that allows further DHW, hair dryers etc after 7am from battery)

 

Hopefully the sun is up and sees you through the day and excess is exported at 15p kWh which is a good return. 
 

run on battery during peak hours then accept after 7pm you’re paying 34p for a few hours before bed. 
 

mix of planning DHW, space heating and charging battery can average out import at about 24p kWh which is good. And obviously over summer I’ll export a lot more at 15p kWh and ensure battery is 100% by 3.59pm

[canalsiderenovation]

I'll be moving to Cosy at the beginning of March. We don't have batteries (yet) but may look into this later in the year. 

[Tomr182]

Likewise. Current fixed ends end Feb so already made moves for Cosy in prep. Be intrigued to see how you find it

[pudding]

My old fixed tariff was due to expire beginning of Feb, so I moved over to Octopus in anticipation of that, and in order to get rebate payments as I've signed up to Ripples second wind turbine project. I signed up via a link to join the Cosy tariff. Got switched over to Octopus week and a half ago, and was switched onto Cosy on Thursday last week.

 

For our house we have an 8kW heat pump connected to a 300L DHW tank and a 300l buffer to tank for whole house UFH. We've also got 7kW solar, with 14kWh batteries installed last year. So, there was a lot of fiddling and tinkering with settings and timers to try and get the best out of it, and it'll take a few more days/ weeks to get the temps and timing right. But basically, the whole aim is to try and run everything ad charge everything during the 2x3hr cheap slots so we import the least amount of electricity possible at all other times. At the mo, I've got the batteries set to charge to 75% overnight which sees us through the morning and breakfast until 1pm easily enough with a bit of spare capacity for charging if/when the sun shines, and then to 100% by the end of the 1-4pm window, ready to see us through the night until 4am. The heat pump is set to come on during the cheap windows to top up the hot water tanks, and the room thermostats are set to heat the rooms only during the 3hr slots, morning up to 20/21 for bedrooms/other rooms, afternoon up to 21/22deg, so slightly warmer to keep a decent temp until they come back on at 4am. 

 

Seems to be working out quite well so far, and I think this tariff really benefits from having batteries which really take advantage of the cheap slots. I think through the year and more solar is produced I'll be able to reduce some of those battery charge levels as more and reliable solar can top them up. Plus, the heating will be off saving muchos kWhs!

 

 

[Tomr182]

Great info! That’s pretty much my plan

good to see it working so far

i only got my system in December so I’m still working out how to make sure the settings are what I want. I’ve figured the battery storage from grid out. Haven’t tried the DHW yet but I will

i hope this has the desired impact for you

[Pocster]

As the sun is slowly but surely disappearing I’m looking at changing from flux to cosy .

I have an ASHP - but how do they know what you’re using it for in the cheaper periods ? . I presume they don’t ; so I could charge batteries twice during the day at a cheaper rate .

Although unlikely to do any export during winter I assume with cosy you can still have seg at 15p ??

[DougMLancs]

I’ve just switched to Cosy and Outgoing Fixed from Flux. They didn’t ask for any evidence of having an ASHP and I’m planning to use the cheap rates for battery charging as well as running the ASHP. It only took a minute and it was live straight away- if the SEG doesn’t automatically change (mine stayed on Flux export for a bit) then give them a nudge (or not 😉).

Edited September 17, 2023 by DougMLancs

[canalsiderenovation]

17 hours ago, DougMLancs said:

I’ve just switched to Cosy and Outgoing Fixed from Flux. They didn’t ask for any evidence of having an ASHP and I’m planning to use the cheap rates for battery charging as well as running the ASHP. It only took a minute and it was live straight away- if the SEG doesn’t automatically change (mine stayed on Flux export for a bit) then give them a nudge (or not 😉).

 

We were on cosy before Flux and we will be moving back to Cosy as soon as I decide to put the heating on (holding out for at least mid October)!

[Pocster]

Suns come out !!!

 

Quick ! Fill yer boots !!

 

Will change to cosy I think - but perhaps stretch flux for a bit longer .. 😎

[DougMLancs]

I should’ve held on a bit probably- I’m just too keen 🤦‍♂️ I was expecting them to come back wanting MCS info for the ASHP and for the switch to take longer. It’s only been 12 C outside this week so I was expecting the heating to kick in at some point but no…

[HughF]

Just about to get my Cool Energy all plumbed in, I feel a switch from BG to Octopus is in the works…

[DanDee]

1 hour ago, HughF said:

Just about to get my Cool Energy all plumbed in, I feel a switch from BG to Octopus is in the works…

Are you going to use my referral code?

[Bob77]

I'm still pondering whether Cosy would make sense for me. At the moment I am on Octopus variable but with Economy 7. The cheap hours during BST are 1.30am to 8.30am so breakfast usage is on cheap rate, and if I am organised I can have the washing machine on overnight and then stick the laundry in the dryer and have it done before the tariff changed. Not so easy once the clocks go back and cheap rate ends at 7.30am.

 

The question is whether with UFH I could store enough heat overnight to keep the house nice and warm using the cheap rate.

During the summer we haven't been using enough cheap rate electricity to make E7 cost-effective - it needs to be about 38% on cheap rate, IIRC, and I have only been managing 25-30%. Once the heating comes on that will change, but Cosy might still be better. I don't like the sound of the peak rate in the evenings though, as it coincides with having the oven and cooker going.

[patp]

Slow cooker?