Cosy Octopus for Heat Pump Owners

koru

If I adjust my spreadsheets to treat the .csv figures as cubic metres, Cozy comes out a bit better than the standard tariff. If I model zero heating from 4-7pm and twice as much heating in the two cheap periods as the rest of the day I get an overall cost nearly 20% lower than on the standard tariff. But on the Agile tariff the same time shifting would create savings of 55%.

In fact, the Agile tariff would save me a lot even over the next few months, until the HP is installed.

I'll probably pluck up courage to use the Comfort app and confirm this.

MultiFuelBurner

cosy is a poor Heatpump tariff imo, Agile or tracker offer far better savings currently.

The price cap has to drop a lot for it to become comoeti for us 

koru

koru said:

I'll probably pluck up courage to use the Comfort app and confirm this.

I've now done this. Interestingly, Cozy comes out £6 more expensive over the last year than the standard tariff (Flexible). But that's based on my current electric usage, before I get a heat pump.

Agile would have been about 25% cheaper overall, though the saving varied from month to month. I've switched to it, as it should already save me about £250 per year. And more if the heat pump goes ahead.

koru

I have finally realised that there's a major advantage of heat pumps that is rarely discussed. With a gas boiler you are paying a unit rate that is the same regardless of time of day. An advantage of a heat pump is that it runs on electric, which means you can benefit from a time-of-use tariff such as Agile, which charges rates lower than the standard tariff most of the day, other than a few hours of peak prices each day.

It is generally said that heat pumps aren't cheaper than gas because electric is about 3-4 times the price of gas, which negates the SCOP efficiency of the heat pump. But that's only true if you compare based on the standard tariff for electricity. If you compare with the much lower average price that you can achieve on a tariff like Agile if you can turn off your HP between 4 and 7pm, a heat pump will give some large cost savings (as well as carbon savings).

Bendo

But then make sure you are comparing tracker gas prices not SVR.

koru

Bendo said:

But then make sure you are comparing tracker gas prices not SVR.

A good point. There's no gas tariff that varies over the day (AFAIK), but there is a tariff that varies daily. Octopus Gas tracker has averaged about 5p over the last year, which is a 30% saving on Flexible Gas (SVR). 

MultiFuelBurner

koru said:

Bendo said:

But then make sure you are comparing tracker gas prices not SVR.

A good point. There's no gas tariff that varies over the day (AFAIK), but there is a tariff that varies daily. Octopus Gas tracker has averaged about 5p over the last year, which is a 30% saving on Flexible Gas (SVR). 

But seasonally (winter) where most gas is used (looking at the last 90 days) it's averaged 4p kWh for many regions.

I am a bit of a pedant on these things when you use the most energy is when you should average not the whole year 

MultiFuelBurner

To expand we have a heat pump but seasonal prices mean those on tracker for gas, heat pumpers can't get close to how cheap it has been for gas this winter.

koru

MultiFuelBurner said:

To expand we have a heat pump but seasonal prices mean those on tracker for gas, heat pumpers can't get close to how cheap it has been for gas this winter.

Is that taking into account the possibility to save more on Agile by turning off the HP during 4-7 pm, when the electric price spikes?

If I take the Agile electric prices charged over Nov-Jan and exclude those three peak hours, the average electric price per kWh in my region (Eastern) was 12.6p. So, even if I just turn off the HP for those three hours and spread the heating evenly over the other 21 hours, a HP would have used electric at 12.6p. Assuming a SCOP of 3.5, wouldn't gas need to average 12.6/3.5=3.6p to cost the same for the same heat output?

That seems to mean that a HP can get close and perhaps slightly beat gas for price, at least if Nov-Jan is representative. I was wrong to say that a HP would give large cost savings, if we use a fair comparison of tariffs. But my main concern is to cut down on carbon without incurring extra heating cost. Any cost savings would be a bonus.

Is there anything I'm not taking into account?

Rolandtheroadie

We've been on them all now. 
 Started on Cosy and tried load shifting, then found out about the octopus compare app. Tracker was around 40% cheaper than Cosy for us, with Agile being around 10% more expensive. 
 Kept checking, Agile is now 10-15% cheaper, we moved over around 3 weeks ago. 
 Initially we were switching the heat pump off from 4 till 7, but we're back to just leaving it on 24/7 set at a temperature it'll never reach so it stays on. We adjusted the temperature we want the house at using weather compensation. 
 High energy users, 12k kWh last year with just over 5k kWh on the ASHP, so it's a good saving for us. Our DD is approx 60% less than we were paying when we first moved to Octopus and it'll cover our usage when averaged out over the year.