Octopus, did i imagine this?

[sharpener]

1 hour ago, JamesPa said:

So far as I can see the best bet at present is the OVO heat pump add on, although I struggle to believe this will be around for long.  Failing that Intelligent Go seems (based on my current analysis) to be the next best as suggested by @Bramco, albeit in both cases without battery.  The battery payback analysis is based on £5K/9.5kWh or £7K/19kWh, which seems to be about par for the course at present unless you self install).  

 

Ovo have had a very bad press for their customer service e.g. here. As well as not trusting their tariff to last long I would be hesitant to put the control of my HP in the hands of their API. Tomato is mentioned there as a possibility too, don't know if that relies on an integration with the HP.

 

Some calcs I did way back showed that the first cost of a big tank of water is about the same per kWh as a battery after allowing for the CoP. The depreciation is however much less, as the projected life is 2 to 3 times as long. And not dependent on usage.

 

But you need a really big tank and lots of room, my 270 litre tank takes up all the space vacated by the oil boiler but it only works bc I am just trying to heat a fraction of the house at any one time (see other thread). The 12kW unit is substantially over-sized for this duty but should be fine when we have guests in the depths of winter.

[G and J]

I’ve just rescanned this thread from the beginning, an interesting exercise.

 

I’m left with the very strong impression that there are things we can do to give us the opportunity of taking advantage of weird and wonderful future electric tariffs.  
 

Slightly overprovision the UFH (closer pipe spacing), slightly oversize the heat pump, and run in the needed cables to add ac coupled batteries.  
 

That way we can add batteries and work in part day heating modes.  
 

Is there anything else we should factor in to maximise the chance of clever future tariff use?

[sharpener]

3 minutes ago, G and J said:

Is there anything else we should factor in to maximise the chance of clever future tariff use?

 

Maxing out PV on the roof is the first investment anyone should make as it has the best RoI of the lot. But not much help from November to February when you need the heat.

 

Things I regret not doing elsewhere include running a 32A supply not 16 to a detached garage, which would have allowed a decent EV charging point. And a cable duct not 2-core SWA in the trench for the rainwater pipe between house and garage.

[PhilT]

9 hours ago, G and J said:

Is there anything else we should factor in to maximise the chance of clever future tariff use?

Take a lot of time and care in working out the justification for a battery. With no export it is marginal at best so why go through all the hassle to install a potential fire bomb in your house. With export I would say impossible to justify on purely financial grounds. If someone has a spreadsheet which proves otherwise, more than happy to concede

[Bramco]

11 hours ago, JamesPa said:

the Cosy tariff is basically, for the average person/house, a battery tariff.

 

Hi James, I don't think you should see our build as a special case, it should be seen as a target for all new builds - but that aside...

 

The Cosy tariff can maybe be seen as a battery tariff but one with a very strict matronly view of when the battery is available.

 

For example, it's a grey day here (again), the oven is on to bake some bread and the batteries are providing the power at 7p on Intelligent Go because we loaded up last night. Anyone on Cosy would have to time this to fit in with their cheap rate.

 

Last night, we dumped about 8kWh at 15p before recharging the batteries - a net gain of 7p - not a lot admittedly but do that every day of the year and it soon adds up. Something you can't do without your own batteries.

 

And the advantage of our build is that all our ASHP usage can be done on the v low nighttime rate. In fact, as I said earlier, due to the batteries all our usage is at the low rate of 7p. So no higher rate usage at all.

 

Simon

[FarmerN]

20 minutes ago, Bramco said:

 

 

 

For example, it's a grey day here (again), the oven is on to bake some bread and the batteries are providing the power at 7p on Intelligent Go because we loaded up last night. Anyone on Cosy would have to time this to fit in with their cheap rate.

 

Last night, we dumped about 8kWh at 15p before recharging the batteries - a net gain of 7p - not a lot admittedly but do that every day of the year and it soon adds up. Something you can't do without your own batteries.

 

 

 

Simon

 

Just suppose I did not have an EV , is the tarrif still avaliable?

I want to do similar to what you describe above , run the house entirely on very cheap rate. Might get caught in very cold weather mid winter when there is little PV production and high heat demand, but currently can run easily on Econ 7.

The EV just might move on in the future.

[JamesPa]

31 minutes ago, Bramco said:

Hi James, I don't think you should see our build as a special case, it should be seen as a target for all new builds - but that aside...

 

I don't see your house (on which I congratulate you) as a special case for newbuilds (although it is in reality judging by whats going up in large numbers locally) but it is a special case for heat pumps. 

 

The vast bulk of our housing stock is existing stock and thus the vast bulk of the heat pumps we need to fit are in these, almost all with radiators.  In that context, which from a climate change perspective is the larger one, your house is a special case.

 

45 minutes ago, PhilT said:

Take a lot of time and care in working out the justification for a battery. With no export it is marginal at best so why go through all the hassle to install a potential fire bomb in your house. With export I would say impossible to justify on purely financial grounds. If someone has a spreadsheet which proves otherwise, more than happy to concede

 

Likewise.  Im working on a spreadsheet (which I will share once its done) but I am not currently finding (for my house - which is probably a fairly typical retrofit with a 7.5kW heat loss) the sweet spot for batteries at their current price.  Givenergy, for example, is (around here) 5K for 9.5kWh and 7K for 19kWh.  If they did the 19kWh model for 5K there might be a case.   So far nobody has come forward with an environmental argument which would tip the balance, so its purely financial at the current time.

 

The biggest challenge with working out the numbers is to estimate how long the battery will last (and thus how much of any more expensive period you can 'ride out').  Because the heat pump dominates the load, this is heavily time of year dependent, so somehow you need somehow to calculate the aggregate % of the total heat pump consumption which can be accommodated at a lower tarrif.  This is not a trivial calculation!  If anyone has magically done this I would appreciate them sharing their method.

 

10 hours ago, sharpener said:

Ovo have had a very bad press for their customer service e.g. here. As well as not trusting their tariff to last long I would be hesitant to put the control of my HP in the hands of their API. Tomato is mentioned there as a possibility too, don't know if that relies on an integration with the HP.

Definitely a concern.  That said, the Ts & Cs don't currently appear to allow them to control the heat pump, which is one reason I think the tariff is unsustainable.

[JamesPa]

18 minutes ago, FarmerN said:

 

Just suppose I did not have an EV , is the tarrif still avaliable?

I want to do similar to what you describe above , run the house entirely on very cheap rate. Might get caught in very cold weather mid winter when there is little PV production and high heat demand, but currently can run easily on Econ 7.

The EV just might move on in the future.

Thats a good question.  |Another good question is - just suppose I have an EV but not an EV charger (so my charge rate is limited to the 10A you can get from a 'granny charger' and cant be controlled by Octopus - is the tariff still available).  The latter question describes my current situation, and I have no need for an EV charger other than to meet the criteria of a tariff (which of course makes it less attractive).  

 

I will ask octopus!

Edited October 24 by JamesPa

[G and J]

10 hours ago, sharpener said:

 

Maxing out PV on the roof is the first investment anyone should make as it has the best RoI of the lot. But not much help from November to February when you need the heat.

 

Things I regret not doing elsewhere include running a 32A supply not 16 to a detached garage, which would have allowed a decent EV charging point. And a cable duct not 2-core SWA in the trench for the rainwater pipe between house and garage.

I think maximising the solar PV is an independent decision that is now self evident in its own right, especially given the saving in slates that flush solar affords.  
 

We've had a reply from UKPN indicating that we can export 5kW, and as our roof will only hold 6.5kW of panels that sounds like a simple system with a 5kW inverter would work. 
 

Add in a ac coupled battery (with therefore it’s own inverter) and that increases my maximum theoretical export capacity and I suspect means investment into more complex control kit and time configuring, further worsening the case for a battery.  
 

 

[Bramco]

1 hour ago, FarmerN said:

Just suppose I did not have an EV , is the tarrif still avaliable?

We haven't. Can you borrow one?

Can't remember the exact sequence of events but we installed solar - just needed the sparky sign off, not MCS. Then applied for Go (although we may have already been on it).

Then applied for Intelligent Go - you need a specified type of EV charger - ours is OK (ZAPPI). Once you are accepted based on the EV charger, you need to attach an EV for the final step. Our nephew has a Tesla, so came along one Saturday morning for a bit of free charge and hey presto, we were on Intelligent Go.  Which gives you and extra 2 hours cheap rate at night and the 15p export.

We installed the batteries after being accepted onto the Int. Go tariff.

[Bramco]

53 minutes ago, JamesPa said:

is the tariff still available

AFAIK, you have to have one of their accredited chargers.

[Bramco]

57 minutes ago, JamesPa said:

So far nobody has come forward with an environmental argument which would tip the balance, so its purely financial at the current time.

Isn't there something to be said for it being environmentally friendly to only use off peak electricity?  I think peak time electricity is the 'dirtiest', i.e. gas vs nuclear or renewable.

 

Simon

[Blooda]

We are on OVO heat pump tariff.  They do not control the heat pump, under the t&c's they can only read data..  They take the kWh used via the API [as long as you have an internet gateway and right model of heat pump], in a month and knock off the difference between your standard rate and 15p /kWh the next month.

 

Cozy would have saved me 40p a year, as we like to cook dinner at their peak rate. 

 

 

Edited October 24 by Blooda

[sharpener]

23 minutes ago, Bramco said:

AFAIK, you have to have one of their accredited chargers.

 

There is a checker on the Octopus web site. You only need an accredited charger (Ohme, zappi...) if you do not have an accredited car.

 

33 minutes ago, Bramco said:

Our nephew has a Tesla, so came along one Saturday morning for a bit of free charge and hey presto, we were on Intelligent Go.  Which gives you and extra 2 hours cheap rate at night and the 15p export.

 

I recall a further condition that you have to charge the EV at least every 30 days. Don't you still have to spend time gaming the system e.g. claiming you need the car fully charged for a night shift at 1 a.m. or something? That is what put me off. Also the cheap periods on Cosy are much better spaced throughout the day, see this thread.

 

1 hour ago, G and J said:

We've had a reply from UKPN indicating that we can export 5kW, and as our roof will only hold 6.5kW of panels that sounds like a simple system with a 5kW inverter would work.

 

Worth over-panelling with 6kW of panels as that will give more year-round exports at little extra cost.

 

1 hour ago, G and J said:

Add in a ac coupled battery (with therefore it’s own inverter) and that increases my maximum theoretical export capacity and I suspect means investment into more complex control kit and time configuring, further worsening the case for a battery.  

 

If you get a 5kW hybrid inverter it will manage all that - even remotely - from the one UI so no DIY controls and no risk of exceeding yr limit.

[Bramco]

1 minute ago, sharpener said:

I recall a further condition that you have to charge the EV at least every 30 days.

Haven't seen that and don't recall any condition like that.  We actually have 2 chargers (planning condition!!) - only one of them is connected to the Octopus app. So how could they know whether we'd charged or not?

An EV is easily sorted though, if it ever rears it's head.

[Bramco]

7 minutes ago, sharpener said:

Also the cheap periods on Cosy are much better spaced throughout the day

But they are 11.86 vs 7 on Int Go.  So  a no brainer if it works for you to use Int Go rather than Cosy.

[JamesPa]

Here is the response from Octopus, basically tarrif not available unless you have an EV and a compatible charger and they actually test that you do.

 

"Thank you for your message and for your interest in our Intelligent Go tariff. I completely understand your perspective on the benefits of having a time-of-use tariff, similar to the old Economy 7.

However, I must inform you that the Intelligent Go tariff is specifically designed for customers with an electric vehicle (EV). To switch to this tariff, you would need to complete a test charge with your EV, as this is an integral part of the onboarding process. Without an EV, unfortunately, it won't be possible to access this tariff.

If you're looking for a time-of-use tariff without an EV, I recommend checking our other available options. Please let me know if you need assistance with anything else or if you have any further questions. I'm here to help!"

[JamesPa]

1 hour ago, Bramco said:

Isn't there something to be said for it being environmentally friendly to only use off peak electricity?  I think peak time electricity is the 'dirtiest', i.e. gas vs nuclear or renewable.

 

Simon

Possibly, maybe probably, which is why I'm still holding out hope that hoping someone would come forward with some facts. 

 

I've also seen it claimed that price is not a particularly good proxy for dirtyness.  I really don't know.  I think somewhere you can download grid carbon intensity, so I suppose I could correlate the two!

Edited October 24 by JamesPa

[SteamyTea]

20 minutes ago, JamesPa said:

I think somewhere you can download grid carbon intensity, so I suppose I could correlate the two.

You can get generation data from here, but you then have to work out the CO_2e multipliers.

 

But as I mentioned, you have to take into account marginal generation supply/demand.

You can start here.

[sharpener]

34 minutes ago, SteamyTea said:

But as I mentioned, you have to take into account marginal generation supply/demand.

You can start here.

 

Good find @SteamyTea, excellent paper.

 

1 hour ago, Bramco said:

So how could they know whether we'd charged or not?

 

Because the accreditation process for your car and/or charging point ensures they have the ability to interrogate your usage profile from one or the other. And can throw you off if they don't like what they see. There has been a lot of discussion on the Camelot forum about all this. I don't think this tariff can last all that long.

 

You didn't reply about having to game the system - perhaps deliberately. It would seem e.g. from this thread that it needs to be something of a hobby in itself and it is easy to make expensive mistakes.

 

I wanted a fit-and-forget solution which continues to work well without attention e.g. when OH is in the house and I am away.

 

Jury still out whether the Victron Dynamic ESS is optimal, I am beginning to think it fails to account for the battery depreciation correctly as otherwise it would not be charging at night in order to maximise export during the day, see pix in this post. Also I don't know how long its self-learning period is or whether it has to start again if I turn it off while we are away.

[SteamyTea]

I still want to know about charging partly degraded batteries.

Say a 1 kWh battery has degraded to 0.8 kWh, I assume that it still takes just a bit more than 1 kWh to recharge it, say 1.05 kWh, but can only deliver 0.8 kWh.

Has anyone got any data on this, or willing to put an input and output meter on their system.

[Bramco]

7 minutes ago, SteamyTea said:

Say a 1 kWh battery has degraded to 0.8 kWh, I assume that it still takes just a bit more than 1 kWh to recharge it, say 1.05 kWh, but can only deliver 0.8 kWh.

Has anyone got any data on this, or willing to put an input and output meter on their system.

Maybe something for another thread?   But I'm guessing that if it has degraded to 0.8kWh, then it will only take 0.8kWh - why would it require 1.05kWh to charge it to 0.8kWh?

 

Our Sunsynk inverter app shows the rate of charge and discharge which seems to show that there are higher losses when charging or discharging at low rates. Ours is a hybrid inverter, so we couldn't put any kind of meter on the system - would be easier with separately ac coupled PV and batteries. 

[SteamyTea]

13 minutes ago, Bramco said:

But I'm guessing that if it has degraded to 0.8kWh, then it will only take 0.8kWh - why would it require 1.05kWh to charge it to 0.8kWh?

Because of the way the ions have to find free places in the chemical matrix.

Think of it as an empty car park. It is easy for cars to park at first, but gets progressively harder, the more cars there are in there.

A degraded battery will have the same amount of ions to move, just less places for them to go, the charging will therefore just keep moving them about, which makes the battery warmer.

Edited October 24 by SteamyTea

[markc]

Regardless of degradation, 0.8kWh battery would require just under 1kWh of input to charge it and you could expect maybe 0.7/0.75 kWh back out of it. Battery round trip efficiency is generally around 80-85%

[SteamyTea]

2 minutes ago, markc said:

Regardless of degradation

That is the bit I have not found a good report on.