Tariff Juggling

I came from OVO where I was only aware of variable or fixed with 4p/kW. export credited every 3 months. Naive or not? To Octopus with a whole range of different tariffs.
I started with fixed before I tried OI and did not dip my foot in Agile. I am now happy with Cozy and 13p/kW lowest tariff for 8 hours in 3 periods throughout the day.
I don't have EV but at near half the Cosy rate it sounds better.
Variables however are EV usage, utilities at night, ASHP in the evening, PV collection and battery storage.
The permutations are many.
Is there a typical user with EV and ASHP and PV/battery?
Is there a consensus on supplier and tariff?

[unknown] The cheapest is probably EON Next Drive, which despite the name does not (currently) require an EV. Something like 6.5p overnight for 7 hours, and export of 16.5p

Cosy does have the advantage of allowing recharging 3 times a day, which works well for a smaller battery. But if battery can last whole day on one overnight charge (plus whatever solar is going), an EV tariff is probably cheaper.
MY EV usage is quite low - a lot more goes through my GE battery than through my car.

(In hindsight, I possibly should have switched to Cosy for Jan/Feb, rather than sticking it out with IOG. If nothing else, heating water at 1pm rather than midnight would probably be a lot more efficient.)

Roy124 So I've got the full suite of Solar+AIO+Heatpump+EV, and I've bounced through a number of tariffs over the past 18 months. Having just come out of winter, here are my findings. [All of these are Octopus Tariffs]

Solar - 4.25kW
Battery - 13.5kW AIO
Heatpump - 9kW Daikin Monobloc
EV - 64kWh Battery

To keep things short, if you have ample battery storage ( >20kWh ), stick to an EV tariff all year round, whether that's GO or IGO. If you're where I am with storage ( <13.5kWh ), GO in the summer, Cozy in the winter for it's 3 charging sessions.

Now, the elaboration;

I've found that with my controversial 9kW Daikin unit (I know a fair number of people have strong opinions on it), it sucks down quite a bit of power in colder conditions. This rather rapidly depletes my 13.5kWh capacity, and on some well below zero Scottish days, it happily consumed 40+kWh on heating alone, not even considering the hot water requirement. Bare in mind that we chose to keep the house at 21C during -8C weather. For that reason, Cozy was a must.

In the warmer months (especially with an abnormally sunny March), my bills are already turning negative, and with temperatures above ~ 7C, the 13.5kWh capacity, paired with solar, is more than enough to get from 05:30 to 00:30 that GO offers.

The breakeven point from Cozy to GO, for lower battery storage, will be based on how much your EV contributes to your bill. If your EV is drawing 35kWh a night from daily use, it might be best to stick with GO regardless, but I know from my usage it isn't even close to that so the Heatpump usually pulls more overall, hence Cozy in the winter.

Agile does throw a spanner into this. When Agile rates are good, and if you have Predbat working it's magic, you can get some truly huge savings. This does require major oversight however, and I wouldn't recommend unless you're monitoring it religiously. Agile hasn't really exceeded Cozy or GO this year yet, so I'm not switching back to it for now. Loving the stability really.

For export, I've pretty much exclusively been on Fixed 15p/kW since getting started. I did consider Agile Export for a while, but never bit the bullet, and honestly I'm no better off anyway as the Agile Export never really stayed above 15p for more than 2-3 weeks.

Hope this helps!

LewisWatt Thanks, great experience

I’ll add my 2p.

Solar - 14.2kW
Battery - 9.5 & 5.2, total 13.5kW (usable)
Heat pump - 2 x 9kW LG Thermal V
EV - not got one yet but am looking at one right now !

Similar to @LewisWatt my heat pumps will guzzle power, on a really cold day I can get through 100kW, but typical winter cold is more like 40-60kW. The EV (when/if I get it) will be low mileage so won’t really sway the tariff decision.
With my large solar capacity I can generate and export enough in the summer to pay for the winter so roughly break even over a whole year.

I’d concur that at the moment Cosy for the winter an Go/iGO for the summer is probably the best tariff. I started on Flux in August 23 but the rates started dropping and knowing that I would be consuming more in the winter went to Agile in October 23 with predbat management. Was very happy with Agile and predbat for most of the time, it was only from the start of this year as Agile rates remained stubbornly high did I start having tariff swap thoughts.
In the end I moved to Cosy in late January 25 and have been saving a few £ a day compared to Agile.

At we come out of winter I’m already seeing negative days (export £ is more than import £), and whilst my batteries won’t last a full day with the heat pump still running and cold nights, its already cheaper if I were on an EV tariff and had a bit of late evening import.
Been very happy with Cosy for the winter though and if Agile doesn’t come down again I will stick with Cosy for next winter.

Although Eon offer what looks like a better import and export rate with no EV tie in, the Octopus Power Up events make me still stay with Octopus. About 10-12% of my annual import has been free on the Power Up events with February it touching 17%.

I think I will need to print these out and work through. I like the point Lewis made about Cosy in summer. An EV low tariff would be more than enough for hot water. We don't heat our hot water until 36 hours after the disinfection cycle.

At the moment EV is just a thought, but energy management is quite complicated now.

Geoffreycoan's point about Daikin was reassuring too. My only excursion over. 50kW was one day in January, 45kW on a few days, but now below 20kW.

Daikin has just updated their App. The schedule setting is very different. Not explored it all.

Roy124 I forgot to say about outgoing rate, I was on Octopus Fixed for all of 2024, but in January 2025 I swapped to Agile Outgoing. Principally because I was never exporting anything in the winter, the heat pump was consuming it all, and the only times I would export would be on a DFS saving event when the DFS rates made it worthwhile to turn the heat pump off for an hour or so, and when exporting I’d be getting a better export rate on Agile outgoing.

This worked fine for January, I got 50-60p/kWh on the DFS export events. By February as it was getting milder and sunnier I was starting to loose slightly at 13p export rates during the day so at the end of February I swapped back to Fixed Outgoing.
I may swap back to Agile Outgoing for next winter, probably just December and January for the same reasons.

@geoffreycoan thanks, that is something else I need to look at, Agile.

https://octopus.energy/smart/agile/

Talking of frequent tariff switching... Things may be changing in the future.

Post on octopus agile forums. No date, or specific details, but a change is coming.

TX200 perhaps in response to (tales of) people switching daily to take advantage of small changes in agile ?