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Ha! Yeah, the trick is to strike the balance between optimisation and living your life without worrying too much about it. As long as it's not too often the occasional grid draw won't make a lot of difference.

No problem. The number of tariffs available now can be quite overwhelming, even without including export tariffs in the mix!

The 'frac export at peak' is the fraction of your total export (solar + battery force export) that you think you can achieve during the peak 4-7pm period. So as an example, if you export 20kWh in one day and 10kWh of that is between 4 and 7pm then the frac = 0.5, i.e. half. When you're force exporting your battery at peak times you'll find that a good fraction of your total export happens during that time, although you may find that a suitable value for you might be lower given you've got a large array which will mean you're exporting more during the day, before the peak period. I hope that helps.

@@TimAndKatsGreenWalk Understood - thanks for the quick response. Do you think it might be a bit late in the year to look at something like Flux/Intelligent Flux considering export has not been setup yet. Also not sure we are ready to hand over control with intelligent. In my simple mind having the ability to discharge only enough to ensure the battery keeps the house going overnight may seem a better option - keep control at the cost of a few pennies. Maybe a barrier I need to get over - also maths isn't my strong point. And I could have just misunderstood how intelligent works 🙂 Thanks for the great content.

@grumpyfather2964 it depends how quickly you can get the export set up. Mine took about three weeks, if I recall correctly, but it can vary. Intelligent Flux does require a bit of a change of mindset, you have to trust that it'll do the right thing and not stress about it. I've let it get on with things and haven't fiddled at all and it's worked brilliantly for me (see my stats videos for proof) but a lot of folks get confused and wonder why the battery isn't supporting the house (it's not supposed to!) or why it's exporting outside of the peak period (it doesn't matter!), but I understand the reluctance. I would suggest starting with regular Flux perhaps, as that's still very good, and it'll give you a chance to get used to things. Alternatively, if you can get onto Intelligent Go (if you have an EV) then that'll be much better for the Winter, so you might not need to switch if you go for that right away.

Feel free to add variable interest to the spreadsheet if you think it'll help.

@@TimAndKatsGreenWalk Haha i'd love to write an excel sheet to predict the markets. Should have said that i thought this was a great video. What i was suggesting is that another factor against investments is that to return the yearly percentage demonstrated your talking about stocks or funds, in this case the S&P. It's not that it's variable per se, it's more that the investment model can get wrecked by weak early performance e.g. if you invest 10k and you the market tanks, you're still taking out your electricity bill each month/year but by the time it recovers your capital has been reduced so even future outpeformance won't get you back on track. If this was a traditional investment to get your 8% PA you wouldn't withdraw in a slump. Again great video!

@@honeypablo74 yes, the uncertainty of stocks investments certainly makes it harder to predict. I'm sure there are some investment evangelists out there who will say you can do a lot better than my figures, but that's a big risk for sure! I'm glad you liked the video.

Yes, I was surprised it didn't fall along with all the import rates at the start of July. As you say, make the most if it while it lasts.

It was your question that prompted this video, as it happens. You aren't the first to ask, so I thought it was well past due some clarification on the subject. I agree it is hard to find the relevant information on the Octopus website.

​@@TimAndKatsGreenWalk top marks for recognising the Octopus tariff conundrum and for taking the initiative to make this clarification video. 👍

@David-bl1bt it was well timed, I was looking for a subject for this week so you gave me a good idea, thank you!

Cool, glad it was well timed!

If you were on a standard tariff with no solar or battery system then running a heat pump would work out similar in cost to a gas boiler. With solar and battery to support it, when combined with IOG, you should find it a fair bit cheaper to run a heat pump than a gas boiler. You might find adding a bit more battery capacity helps too, as that extra battery can be used to effectively run more of your heating at the off-peak rate. We have 14 kWh of battery and last Winter we ran our heating almost entirely using off-peak power, all except the coldest days. However, even with a modest battery you should find that you can cover a good fraction of your heating in the autumn and spring with off-peak power or solar. I hope that helps.

You might find this of interest too: czcams.com/video/q1tYCenxb2M/video.htmlsi=lgu_4O-EK5Um3ek5

@TimAndKatsGreenWalk thanks so much. At the price they've quoted, it seems to make perfect sense. We can't really afford another battery as well as a heat pump, but my head is fairly convinced about the potential savings. There aren't many real-world experiences out there at the moment, so you giving an answer is very helpful. Thank you!

@@Simonstunell1974 no problem. It's worth seeing how you get on in the first winter with the heat pump. You might find the amount of battery you have is sufficient. In either case you'll have some data to work with then.

I don't have first hand experience of other suppliers so I'd rather not.

That changed the game, really. It's an amazing combination that's hard to beat.

@@TimAndKatsGreenWalk Very hard to beat IOG indeed. In the whole market only EON Next is more competitive than IOG

@@serraios1989 yes, that is a great tariff too.

Sadly appearances can be deceptive. There isn't quite enough extra room on the E/W sides, although that would be great if it was doable. I'm still keeping the North facing roof under consideration, so maybe one day I'll add some panels there as I think it might still be the best option as long as the install can be kept to a reasonable cost.

Can't share images via this message system, but I did a month end data grab from the SolarEdge system on our garage. For July, the north facing panels produced 80% output that the south facing achieved.

@@JimGayes that's impressive. I used PVGIS to see how the North roof could perform and in the Summer it was surprisingly good. Not so great in the Winter compared to South but the extra export in the Summer would help build up a healthy amount of credit for the rest of the year, for sure.

No problem, I'm glad it's useful!

It's always interesting hearing other people's stories.

That sounds madening. This tarrif was designed for folk like you! We have a Tesla MS and a Mini EV. When I signed up I was asked to pick one and use that to link with Octopus. At the time, both were compatible but Octopus could only register one car as multi-car was a work in progress, perhaps it still is. As our Mini would be charging more regularly I tried to register that one through the Octopus app, but it just wouldn't finish the process. So I tried the Tesla MS and it worked first time. Over a year later and we are still enjoying IOG and the 15p export. When I plug in the Tesla, Octopus control the charging and when I plug in the Mini I just do timed charging starting at 23:30 to ensure the cheap rate. I feel your pain. Perhaps an option is to start a second Tesla account and move one car to that? I am sure you have already thought of this though, so forgive my suggestion.

@@Ben-gm9lo thanks & yes it’s frustrating, particularly as we were charging exactly as you are! Both our Teslas are leased so I can’t transfer one to my wife & the Tesla Wall Connector isn’t compatible with IOG. I’m sending Octopus weekly emails to ask them to extend the number of vehicles to 2 (or more) which would solve the problem. We’ll see.

Oh that's annoying. I hope they can get that sorted soon. I don't think I have any advice to offer other than chasing Octopus, which you're already doing. You can't be the only ones with this problem.

@@humphreybradley3060 Oh dear, what a pickle. My immediate reaction is upgrade your EV SE from Tesla to something compatible like a Zappi, but that is around £1000 to solve a problem that isn't even yours! I do hope something gets resolved, you have done everthing right yet the situation confounds you. Best wishes.

You need an MCS certificate and letter from the DNO, so as soon as you've those you're good to go. You don't tend to get those until after your system is commissioned though, so I don't think you can get much of a head start on it. Switching to IOG requires a test charge so you'd need an EV and charger first.

@@TimAndKatsGreenWalk Kewl, than you 😎👍

That's excellent, great to hear. I also spend far too long checking my various apps throughout the day!

@@steve_787 I guess once you work out the general pattern you'll spend a little less time glued to the market 😄

@@steve_787 I am in the process of getting solar and I am evaluating my options . I can fit 4.5kw of solar 5kw inverter and I think 15kwh of battery storage. Some say I only need half that storage , but due to work my house can be empty for upto 2 weeks at a time. I believe the extra storage will give me options on when to keep or export energy.

@@Disco45 I have Agile import and standard 15p export with a 5.8kW battery. I use about 10kWh per day, so the battery isn't enough to see me through in the winter when solar production is a bit low. However, the cost for the additional battery capacity buys an awful lot of electricity. I worked out it would be a similar payback time to my whole system, and decided not to go for it. On average I pay way less for my electricity per kWh than I do import.

@@Disco45 WIth my battery (9.5kWH) I find that literally 99% of my usage is offpeak because I'm filling the battery off peak and using it during the day. Hwoever I ahev an EV which enables me to get that off peak 7p rate. Do you ahve one? If not its hard to see what a large battery will get you. In winter your solar is unlikely to give you enough for a day and you might need say 3 or 4 days to fill up 15kW. Perhasp you think you can fill it up when away and use it when back but thats only good for a coupel of days most likely. The key is to get a higher export rate than daytime use rate.

Yes, that's what I did last year and it worked well.

@@TimAndKatsGreenWalk It does seem a more relaxed way than watching agile all the time. I guess with agile you could still follow the same pattern as in general the lows and highs follow a predictable pattern.

@@Disco45 that is true, yeah, it does have some consistent patterns. There are also some third party services that can automate it for you: czcams.com/video/Nmk7M156_PE/video.htmlsi=_o7QjlxW3c4_rYAD

I got very close last year. Total bill for the year was £220.

Erm, no, that's not what I'm showing. If you're generating 30+ kWh in a day you can't use all that. You should get paid for it at the highest rate you can. I earn quite a bit in the Summer from my export.

It's very viable to export especially if you, like me, are on Intelligent Octopus Go. I can fill my 13.5kWh GivEnergy All-In-One battery as well as my car at night for 7p/kWh and export everything I can during the day for 15p/kWh. I'm 8p/kWh better off doing that than consuming what I generate during the day and exporting the rest.

@@FFVoyager quite.

EH? I import at 7p at night run my house off that and export all solar at 15p so it makes no sense at all for me to use my solar.

@@Joe-lb8qnExport your solar energy as well!

The rates are in the spreadsheet if you want to check it out. 15p/kWh for IOG and Cosy (Outgoing Fixed), 8 for regular Go (Outgoing Lite), and the Flux tariffs have their own export rates. These are the best export rates that you can get for each of those tariffs. See 1:43 in the video.

See this for details: octopus.energy/help-and-faqs/articles/which-export-tariff-can-i-combine-with-my-import-tariff/

Hi Tim, thanks for your prompt response with this info. I have solar, battery (giv AIO), EV. I dont have a heatpump as yet but planning one before winter. My thoughts are Cosy as it gives 3 off peak sessions, so would give me the opportunity to charge my AIO and car if necessary 3 periods per day, added to the fixed export of 15p for excess solar produced during the day. Assuming of course I can have the cosy tariff without a heatpump (currently)?...or do you need to prove that you have one to sign-up to the cosy tariff? And, also assuming that I can attach the fixed outgoing tariff to cosy? Is this possible/feasible? What are your thoughts?

@@David-bl1bt yes, you can get outgoing fixed with Cosy (see the link I posted). Personally I would stick with IOG because the off-peak rate is so much better than Cosy. You can't get Cosy without a heat pump as you need the MCS certificate to sign up. The AIO is a big battery so you will probably find that it's sufficient to run a heat pump for a good fraction of the Winter without the need to charge it more than once per day.

@@David-bl1bt you can see some of my own experience with a similar amount of battery to you in this video: czcams.com/video/_qysulne5g0/video.htmlsi=EOvVxTfRzWMlpm6L

The specs for the Powerwall 3 are certainly very impressive.

You're not the first to point this out. I guess HeatPunk is erring on the side of caution, but regardless it's good to know that modern triple glazing is so good.

No problem.

It has very much become my hobby, I'll admit that!

Not really. Very simple.

They charge from the grid and solar. If the solar is more than the charging rate any excess gets exported, yes. Charging only ever happens outside of the peak times. Discharging tends to happen during peak times but sometimes they discharge for a few minutes outside of peak times too, as shown in the video.

@@TimAndKatsGreenWalk Thanks for clarifying.

Ps we're going to be adding these to our website for full install service from August.....

Nice. Yeah, ours has been working great so far.

That's not a bad shout, we had ours running without ducting for a few days when it was hot... Cooled the utility room down nicely!

@@Eggnog3000 exactly. No point in wasting that chilled air. Utilize it. That should be included in the SCOP rating

In theory that's a good idea, but from a practical perspective it would be complicated and expensive to do, so no, not worth doing, really. The small savings you'd make (about 20p per day for a few weeks a year) would never cover the extra cost of adding such a system, unfortunately.

That's a good plan.

Cool cool. Plenty more videos to come!

It was a lot of fun watching the whole install process and chatting to both the installers and Mixergy folks. It's been operating really well so far and I'm very much looking forward to showing more videos on the ongoing operation too.

Yes, it's about 70cm. For comparison the space we've got ours in is 75cm wide and it has some margin for error so 70 should work.

@@TimAndKatsGreenWalk thanks!

The garage is insulated too, and tends to stay above 12 deg in Winter, so the extra heat loss won't be too great (not enough to outweigh the extra efficiency, for sure). We'll discuss the reasons in more detail in a future video but it was a combination of being more convenient for the vents and also to minimise the noise impact.

I'd never considered putting our tank in the garage before seeing your video. I assume 3 of the 4 walls are insulated (integral garage). Good option to free up storage inside the house. Very much looking forward to seeing your results and impression in upcoming videos.

Yes, it's an integrated garage. All the walls are insulated, and it has an insulated garage door. I've got a thermometer in there and last Winter it never went below 12 deg.

I'd be surprised if the efficiency of your battery is much less than 88% round trip (6% loss AC-DC then 6% loss DC-AC). Mine is certainly way better than 70% (about 92% according to my June values). You'd have those same losses regardless of tariff, of course.

@@TimAndKatsGreenWalk Since June 2022 when we had the pv system installed, the efficiency (battery discharge/battery charge) is 94%, according to the data from the GE app. My experiments however showed efficiency 70%, using data from the smart meter itself. Battery needs 10kwh to fully charge from empty at max rate and delivers 7kwh at forced discharge.

Yeah, I think they look cool, too.

Good stuff. Hopefully I'll be able to get the next one out soon.

Nice! I hope your install goes smoothly.

You mean the air ducts? Yeah, it needs a lot of airflow to work.

There was no pressing need to get rid of the old cylinder, really, you're right. We were using the immersion on a timer using overnight power, so it was not expensive to run, it's true. But I wanted to get closer to being a net exporter rather than net importer of electricity across the year, so this is another step towards that goal. Freeing up the airing cupboard is a bonus too. We'll cover all that in more detail in a future video as well.

@@TimAndKatsGreenWalk Thanks for your comments. Yes, it makes more sense now

Yup, I'll be covering that in a future video. I'm definitely glad we put it in the garage, but with sound proofing it'd probably work in an airing cupboard too.

Yeah, it's clever stuff.

Yes, but mostly just using it as a timer, rather than solar divert (since the export rates are so good now).

No problem. Lots to share.

I was very pleased with it. Worked out better than I expected!

Thanks. I'm excited to share more about it.

I suppose I could disconnect the exhaust vent. Not sure it'd be worth it though.

They do. Just not many in the UK at the moment. I have the Hitachi Yutampo Twin with 2 internal units and the 190L cylinder. According to my installer, Toshiba does one but it's prohibitively expensive. Daikin do one too (Multi+), but in the UK the cylinder is tiny - 90L or 120L.

U can get the Dakin multi plus system that does hot water and air to air heating and cooling.

As others have mentioned, they do exist but are rare in the UK. I covered the Daikin system here: czcams.com/video/9domQlKtbBQ/video.htmlsi=vXK41ZZIab0bTsRg

Yes, although that might have compromises that mean it's not as beneficial as you'd think. Some AC systems can use the heat that would otherwise go to the atmosphere to heat water, but they are more complicated and expensive, for example.

Yes, I discovered that too.

Ok, good to know, thanks.