Octopus ASHP Octopus Tariff

BedrockFred

Having a Cosy9 installed soon and was wondering what my best tariff would be 

Have Solar (Roof rent scheme) no EV 

Any thought appreciated 

matelodave

You really have to work out whether you can fit your heating times around the low tariff periods and avoid the high tariff periods. Its also worth checking if you have to pay more for the normal tariff periods and standing charge are more expensive than a flat rate or fixed tariff.

The Eon heatpump tariff looks pretty good as it is based on the SVT, with a low rate of 10p less than SVT during six hours and no peak rate unlike the the Octopus offering which has a high peak rate when you want to cook your dinner.

In the end you really have to find something that fits your lifestyle and heating requirements especially if there's an elevated cost for using everything else, there isn't a one size fits all. Perhaps it would be better to see how you get on with the heatpump and learn how it works and to drive it properly rather than trying to fit its operation around a specialised tariff which may not actually suit you.

I''ve got the lowest cost fixed tariff that I can find (currently 20.35p/kwh) which means I can run my heatpump 24 hours a day at a low level rather than trying to persuade SWMBO to use leccy during off peak times and avoid peak rates. It also saves big temperature fluctuations by trying to maximise its use during off peak times and minimising it when electricity is more expensive.

I'd probably have a different perspective if I had solar AND batteries or an EV but I don't.

zxzxzx

Octopus recommends Cosy, modulate temperature up 2/3 degrees when cheap, your chosen temp when normal and 2/3 degrees down when it is expensive. 

All managed in the app.

Seems worth trying?

matelodave

zxzxzx said:

Octopus recommends Cosy, modulate temperature up 2/3 degrees when cheap, your chosen temp when normal and 2/3 degrees down when it is expensive. 

All managed in the app.

Seems worth trying?

Doesn't winding it up when its a bit cheaper and then cutting it down a bit during peak times negate the object by almost averaging out the difference.

A heatpump uses more electricity when its turned up (it becomes less efficient) than when its turned down so although you'll pay a bit less per kwh when its cheaper you'll use more kwh. The net effect probably isn't going to make a lot of difference to the cost even if you do turn it down a bit during the three hour peak period.

As I said above, you need to see how it fits your lifestyle and do some careful sums to see if a heatpump tariff will suit you or save/cost you money.

matt_drummer

zxzxzx said:

Octopus recommends Cosy, modulate temperature up 2/3 degrees when cheap, your chosen temp when normal and 2/3 degrees down when it is expensive. 

All managed in the app.

Seems worth trying?

That assumes that electricity use and heat output are linear and in proportion to a set temperature.

What temperature are you turning up and down, the house or the flow temperature?

Heat pumps don't respond to changes instantly, whilst the flow temperature can be changed quite quickly the heat output will take much longer to respond.

And it is the heat output and efficiency that ultimately determine the amount of electricity used.

These do not work like gas/oil boilers and other types of electric heating.

The suggestion by Octopus is likely to you less heat and use more electricity than just letting the heat pump run at its optimal flow temperature to match the heat loss of your home at the desired room temperature.

If you chose Cosy then it would be a good idea to do heat your DHW in the cheaper slots and ideally at the warmest part of the day.

I would do as @matelodave does and just pick a standard tariff unless you can move other use to the cheap Cosy slots.

zxzxzx

I haven’t tried it, but will when mine is installed. I believe it will work for me as I have solar & batteries maybe not the OP but may be worth trying, as I said.

https://octopus.energy/heat-pump-help/cosy-schedule/

Spoonie_Turtle

We don't have solar, only the heat pump but we are high users for context.  And we turn off the heating for the 4-7pm peak, as we don't have a setback facility.  Agile throughout most of the year has worked out cheaper for us than the Cosy tariff (which in turn is marginally cheaper than the SVT) - but not having solar means we benefit more from the cheaper daytime rates than someone with solar would, which applies to both Agile and Cosy.

EDF have a FreePhase tariff which is a sort of flattened and simplified version of Agile, and a halfway point between Cosy and Agile.

Actually just having a look at the time blocks for FreePhase, that might be ideal for someone with solar and a heat pump.  Properly cheap electricity overnight and during the sunnier daylight hours. 
[It would take a lot to lure me away from Octopus but *if we had solar* that might actually be the perfect tariff for us with our usage patterns.]