As you may know @mars, we are trying the newish Octopus Energy Cosy tariff (that I refer to as ‘MK11’). This revised version allows a total of 8 hours at the cheapest rate spread over 2 x 3 hour and 1 x 2 hour slots and is thus easier to take maximum benefit from than the previous offering. We have a SMETS 1 (updated) meter that can discern the half hour slots and we have been using this for Agile tariff too. As you say, an ASHP would be best fed with power 24/7 which would necessitate some higher rate energy being used during some of the other 16 hours a day; we run our system 24/7 but, via the Tesla app, charge the battery and only use the grid during the 8 cheapest hours. Of course the meter still needs to report the consumption relative to times of day but it is very satisfying to see those long gaps without any consumption on the OE app! Regards, Toodles. 

It's really puzzling that ASHP tariff are two or 3 short cheap slots per day, which is really sending the wrong message. As said the heat pump should really be left to tick away all day, every day. Not used like a gas boiler.

The time slot tariff like cosy, should just be called battery, because that is the only way you benefit.

The whole smart meter or no smart (we have no signal to ours) is not really good either. If the system doesn't allow you to have a smart meter, you are excluded from beneficial tariffs. Even PV exports I would only get 4.5p per kWh, instead of the smart tariff exports at 4x that. Lucky I don't export, I would be really cheesed off.

Heat pumps, of course, generally keep track of their power usage so the most accurately targeted, IMHO, would be a tariff for a consumer prepared to allow the energy provider to query that consumption data. That way, people could be billed a lower rate throughout the day for energy proven to be for certain specific uses. Other devices (e.g. electric vehicle chargers) could be treated in a similar way.

Not saying that's practical, of course, or even necessarily ethical; merely that it's technically perfectly possible.

Posted by: @majordennisbloodnok

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Heat pumps, of course, generally keep track of their power usage so the most accurately targeted, IMHO, would be a tariff for a consumer prepared to allow the energy provider to query that consumption data. That way, people could be billed a lower rate throughout the day for energy proven to be for certain specific uses. Other devices (e.g. electric vehicle chargers) could be treated in a similar way.

Not saying that's practical, of course, or even necessarily ethical; merely that it's technically perfectly possible.

I suppose that this is the World in which we live.

I hope that most people with an iota of common sense would appreciate that we should all do our best to limit global warming, unfortunately many would prefer that others pay the bill.

While having special tariffs for heat pump users may help increase adoption of the technology, it is at the moment the few being subsidised by the many, but what happens when we get to the point when it is the many being subsidised by the few?

Of course, it might not end up as a subsidy at all. It could equally end up as a systemic overcharging per unit except where a cap is put in place for certain types of usage. Not saying that looks any prettier, of course....

And we also cannot ignore that the precedent has already been set. Red diesel for agricultural vehicles, for instance.

@majordennisbloodnok On July 1st., we swapped from OE’s Agile tariff to the new Cosy (MK11 I call it) and although a month in mid-summer is hardly a comprehensive period of trial, I have nevertheless been looking over my shoulder and comparing Cosy with Agile. Using Agileprices.prices.uk site and referring to the figures in the monthly summary for July 2024, I find that the average off peak rate has worked out at 15.9 pence per kWh. for Agile (am not sure if this includes VAT or not). The Cosy rate during the 8 hours of the cheapest rate has been 11.2 pence per kWh excluding VAT. These arrangements obviously work best if energy storage is available like wot I have.

In the past, I compared Agile with Cosy (MK1) and using the same storage facility, I found I could make savings on Agile. I am unsure what has changed but it seems to me that Agile has enjoyed far fewer cheap rates and plunge prices than in the recent past (over the previous 12 months). I may have been looking at Agile with rose tinted optics as I think the Cosy MK1 price was a little higher than Cosy MK11 is now and this may have been influencing my expectations for Agile to be the cheapest. Though I realise I have the option to change my tariff at will, my present feeling is that Cosy MK11 is working out quite well for me. Regards, Toodles.

@toodles, to be frank the amount we could save by tariff watching and regular switches is pretty small compared with the effort of working it all out so I apply the 80:20 rule. We've managed to deal with the big savings and so what's left is now just all in the noise. Our average import rate (with standing charge removed and including the Vodka And Tonic) for June worked out at 16.2p per kWh which I don't think is too shabby.

For you, of course, that stonking great big battery makes a massive difference compared with our situation, and I can easily see why it would be well worth your while investigating even pretty small unit price savings, especially when comparing cheap times with expensive ones. Our 6kWh battery wouldn't allow us to do any significant time shifting on the scale you do, but it does allow us to avoid the peak times. More importantly, whilst the sun is shining, we're generally importing less than a kWh so in real terms a 5p/kWh difference in unit rate would save us about half a percent of knack all.

Now we have an EV, though, that's all highly likely to change; let's see.