@chandykris 

In the winter period, i boost the temp during the 8 cosy hours by 0.5C, and the 4-7p period drop it by 0.5C

This gave me 85%+ usage off the night rate, i have a 5kW battery. I worked out i would need 10kW battery to take me to 95%+, that would take 20years to payback so not viable unless battery prices halve this year.

Now were in the summer usage period, heat pump is set to maintain only overnight until 7am when cheap cosy ends, then i switch to solar for the day

@agentgeorge 85% usage during off-peak rates is quite good. We have an Aira heat pump and can't boost temperatures during certain times of the day. Technically there is a smart tariff control option and comfort control that allows more variations in indoor temperature. So, the system should automatically boost and drop temperature based on tariff rates. But whenever I have turned it on, it just runs hot water at peak times, so I have lost faith and turned it off. To be fair, the Aira support team has mentioned that let it run for a couple of days and Aira Intelligence should learn by itself. But, the control freak in me won't allow the system to take full control!

Makes sense about holding off the battery expansion with a 20 year payback, end of the day renewable tech investments should give financial returns too.

@chandykris ive mentioned previously i researched heat pumps for over a year, reading mars’ forum extensively. I learnt R290 was the new gas, which id come across in Automotive forums as being the future regulated cooling gas. R134a was phased out by EU by 2025, wonder if thats for all new installations. 
i chose cosy6 as it used R290, octopus initially tried to tell me i needed a Daikin8, i argued i would insulate more to achieve a heat loss under 5.5kW/h at -6C to get the BUS grant. I didnt agree with Octopus’s heat loss calcs as id done my own and got lower. We argued for weeks but i stood my ground and we came to an agreement that i would improve the insulation by the time they applied for the grant, bit of a fudge but i accepted the challenge. The first winter was not good for the Cosy6, it barely coped with the heat loss. I should add i am renovating and extending my 3 bed house to 4 bed 2.5 bath, Octopus wont quote on renovation projects so again we had to look at the heat loss when building work completed sufficient for them to quote again 6 months after the first survey, when the manager came in to redo the survey with all the improvements, then they agreed to install. Ive also opted for UFH which works well with low flow temperature heating, you dont need a blend valve and second pump!

i have a full years costs in for running the house on electric, heating, cooking, EV, ive averaged £60/month for the past year, 85% of my usage being at the cheapest cosy period of 8hours

My yearly SPF is 3.89

My average unit cost was 12.56p/kW

My energy bill this year is 47% using cosy6 tariff than using Gas Boiler.

if I was on a standard tariff i would only just break even

i read yesterday government is “looking” at the ridiculous cost of how electricity is priced per kWh per day. Linking it to Gas price is arcane and punishing businesses in UK

According to BBC news, US electricity costs 6.5p/kW, UK 26p/kW

@agentgeorge And the Americans think that their energy prices are high! Hey Ho, Toodles.

@agentgeorge Our running costs are so similar and off by £1 per month! Our running total for the past 12 months is £708 and averages to about 11.7p per kWh. The heat pump running costs are about £330 per annum, only 40% of what it would have cost us had we been on gas. Not to mention the additional savings of £30 per month for boiler cover, as we got the 15 year all inclusive warranty from Aira that covers maintenance as well.

Having said that it's likely to go up to £800 after we decided to fix Octopus Go for the next 12 months. I was thinking our off-peak usage is about 75% to 80%. While that's the case during winter months, for the whole year we are averaging 85% too. 

If I were to design a combined tariff for all renewable tech combined, I would do the following. Two off-peak slots, 12:30 am to 5:30 am and then again from 1 pm.to 4 pm, at around 12p over kWh (average of Fixed Octopus Go and Cosy Octopus off-peak rates for our region). This will enable people who need more charge into their EVs who don't want to be restricted by just 3 hours off-peak of Cosy in the morning. This would also enable heating the hot water during afternoon off-peak slots. Usually DHW takes about 1.5 hours to 2 hours during the winter months, and it means heating has to run at full pace again after DHW run as indoor temperatures do drop a bit if house is not heated for a couple of hours in the winter. We can also run appliances like dishwasher during the afternoon off-peak slots, charge the batteries again and put some heat into the house. So, we can avoid touching the grid from 4 to 7 pm which invariably happens with Octopus Go in our case. Also, as the off-peak import rates at 12p would be same as export rates at 12p, there's no incentive to charge off-peak and export later during peak PV generation months. But, for consumers with larger battery capacity or South West/West facing panels, export during the 4 pm to 7pm will help the grid from April to August. Overall, it wouldn't be much different financially, but just suit consumers with all the renewable tech better. Or may be it will just suit our house better!!

@chandykris Well, there are a few factors that I think helps me to heat the house for 6 hours and be enought for the whole day in winter conditions.

Factor 1:When we built the house, becuse of mistake we had to put 15cm of celotex insulations in the floor under the underfloor heating tubes.

Factor 2: My brother, who did the underfloor heating put in 20mm piping in which is bigger the usal British way.

Factor 3: The heatpump is bigger oversized for the house.

Factor 4: I use the immersion heater to make the hot water so that the heatpump can focus on only heating as we only have 6 hours to run it.

Factor 5: I never used to use the backup heating in my hetpump as it is not needed when u use it normal. 24/7 Also your cop goes down when it kicks in. But when the electricity is almost 5 times cheaper it doesn't really mater and it only kicks in below 0 Celsius outside temp.

Factor 5: I turn up the weather comp so the flow temperature is higher.

I have to admit when it is really cold the upstairs, where I have radiators that does kick in for short time, but I have never seen the downstairs kick in. The temperature downstairs kept nice and warm about 21.5-23c.

Hi everyone,  I posted some time ago about possibly getting an EV and using it for V2H.  From what I can see,V2X is definitely some way off and it seems likely EV manufacturers are going to make it difficult.  So the Octopus link to only a few vehicles such as BYD takes me out of the market as I am not into buying new.  Instead we are probably going for a 10 year old Nissan Leaf charged via 13amp socket.  Minimum costs and nothing smart.  Am I stuck with a standard variable tarrif?  I have been told EDF have attractive tarrifs but EDF won’t tell me what they might be until I have signed up with them!!  Given their standing charge is 8p per day more than OVO, it’s not encouraging.

Can anyone make any suggestions?

For reference, the 24 kW Leaf would be for very local running only.  I have seen one locally and the owner is very positive.  A range of 80 miles is adequate and an overnight charge should do the job.

@davidb no, I don’t think you’re stuck with a standard variable tariff simply because you’re buying an older Leaf and charging it through a three-pin socket.

The automated tariffs may be unavailable because they need to communicate with a compatible car or charger, but there are still straightforward time-of-use EV tariffs that simply charge a lower rate during fixed overnight hours. I'm actually working a tool that will hopefully help homeowners make decisions similar to yours.

Octopus Go is probably the most obvious example. Octopus says it works with all EVs and chargers, that you do not need a dedicated home charger, and that the discounted period runs from 00:30 to 05:30. You would need a compatible smart meter I guess.

EDF’s GoElectric may actually suit slow charging better because its off-peak window is seven hours, from 11pm until 6am, currently at 6.99p/kWh. EDF also says it works with any EV or charger. Their slightly odd process appears to be that new customers initially transfer onto the standard variable tariff while EDF connects to the smart meter, after which they are moved automatically onto GoElectric. That may explain the confusing response you received.

British Gas also currently offers five hours at 9p/kWh between midnight and 5am and says its tariff works with any EV and home charger.

With a three-pin charging cable, the longer EDF window could be useful because the car will only charge at roughly 2–3kW rather than the 7kW available from a wallbox. Seven hours should still add a useful amount of range for the local journeys you describe, although it would not necessarily recharge a depleted 24kWh battery completely. If you've got PV, you could top it up from their with excess production.

The additional 8p daily standing charge is about £29 per year, so I wouldn’t reject EDF on that point alone. The more important comparison is the complete tariff: daytime rate, standing charge and how much of your total household consumption you can move into the cheap window. If the Leaf is doing very little mileage, an EV tariff with an expensive daytime rate might not win overall. If you can also schedule hot water, appliances or other loads overnight, it becomes much more attractive.

Posted by: @davidb

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nstead we are probably going for a 10 year old Nissan Leaf charged via 13amp socket.  Minimum costs and nothing smart.  Am I stuck with a standard variable tarrif?

No.  I had the same charging arrangements for a couple of years and used Octopus Go and EON Next.  I used a 16A Shelly relay embedded in the back of the socket to switch the socket on and off according to the schedule.  For a while I even had it switched on and off according to solar output (via home assistant) but dropped this complexity once my export rate exceeded my night time import rate.

Note that standard 13A sockets are likely to get warm if you charge for more than a couple of hours.  There exist EV rated 13A sockets that are more robust.

I have subsequently got a charger and shifted to Intelligent Go, mostly because the cheap rate period starts an hour earlier and is an hour longer, which is better for my heat pump and scheduling overnight use of high consumption equipment.  It will take several years to pay back the cost of the charger though, so its as much about convenience as it is about money.

Note that if you are doing your own electrics you must observe all relevant regulations!

"Their slightly odd process appears to be that new customers initially transfer onto the standard variable tariff while EDF connects to the smart meter,"

Most suppliers do this because they don't want you on an EV tariff for a month then have to tell you that your meter connection sucks and sorry we are taking your new toy away. This makes customers very very angry indeed.

Go is the obvious simple one. Not sure IGo is worth the complexity any more. Octopus are at the point they are now putting out videos trying to justify and explain the incomprehensible mess and have to block comments. So the PR front is going swimmingly.

Reading between the lines of what octopus are doing with iog they have discovered that people only plug their cars in when they actually want to charge, which isn't that often (in my case, typically < once per week on average).  This means that the ability to use the cars to dump excess leccy is somewhat curtailed.

The controls in the app also appear to be ignored, at least in my case.  I ask for 60% added charge and yet it schedules a full charge at more or less any time if day, which (it claims) means I get cheap leccy for the house during all of those times as well as at night.  It then complains when the charging stops because the battery is fully charged.  It's entirely believable that this isn't sustainable, and doubtless there are some are gaming this failing and getting cheap leccy for their home for 12 hrs per day or more.

So Octopus are making some fairly simple changes in an effort to address this, which they are describing in a hopelessly over complex way, and then making even more complex by adding silly fish with no clear link between the fish and anything I (or anyone else) is likely to be interested in.  Unless the controls in the app start working either it won't address it, or customers will get a shock and goodness knows what effect the fish will have, if any.

This was always going to be difficult not least because it involves human behaviour, but it feels like octopus have made it much more difficult than they needed to.

Hi. 

I have 16 panel solar panels producing about 20kw on a sunny day 

A Tesla powerwall 2 storage battery 

Also an ev but do not do a lot of mileage 

Now I'm having a heat geek ASHP Vaillant 12kw. Installed 

Currently on octopus intelligent go and outgoing octopus.

Is this a good tarrif for me to be on or should I be looking elsewhere.

Any advice greatfully received.

Regards Pete