How to getthe best out of Octopus Flux

[Ron-ski]

It's Flux import only for now I think? I'm sticking on Go for now to keep costs down, even if the export rates are poor, I'm not really exporting anything at the moment.



Just go into the portal online and then into My Inverter => Settings. You can set a timed charge of the battery here.

I'm not 100% on this, but if I was on Flux I wonder if the best strategy is to:

Set charge to 100% from 02:00 - 16:00
Set discharge from 16:00 - 19:00

By doing this you will hold the battery at 100% all day, no matter the weather (excess generated solar will go to export to grid on a good day). Then export for the maximum payment you can get down from 100% to whatever it can export into that 3 hour window.

This seems sensible because you lower the battery cycles, it would be one complete cycle per day. Thoughts?

I guess it's a balance between export rate and import rate and usage. If the weather is good then the batteries will fill and there's no need to top up. I'll need to have a think about it.. problem is 4-7pm is prime cooking time so it's going to have to be a balance between grid usage and discharge.

In my suggested method above it limits the cycles, if you alternatively charge to 100% between 02:00 - 05:00 and then allow solar top it up before exporting, there is ultimately more wear on the batteries for potential small gains in the daylight hours.

Also depends if you want to attempt to export as much as possible for the maximum payment you can get.

If you can use most of your generation efficiently with Go I think that will still win in the long term, though it's a bit more annoying to min/max it.

I can't be on Go

I like your method I just need to work it out based on our usage.

The way to approach flux is going to be highly dependent on your own personal set up and consumption habits. To min max it you’d need to be looking at it daily which is going to be quite a hassle.

For me, I’d want to be holding onto about 5kwh of battery to see me though the evening peak and then just letting the solar and battery do it’s thing for the rest of the time. I’d be Charging the battery off peak in winter and not in summer.

I'm all signed up now too.......

In my mind I'd be charging to 100 in the 2am to 5am window then exporting everything else during the day and forcing a discharge between 4 and 7pm. With my gen1 inverter I could maximally charge and discharge 7.8 in this period so something like £2 every day profit on top of whatever you export which cojld be 20 or 30kwh in the height of summer and that's if you have to fully charge your batteries.

 

[Ron-ski]

It's Flux import only for now I think?

I've had an email saying that Flux import is live, but I wonder how long before export is live? My account still shows they are setting something up.

I'll need to think about strategy, but yours sound along the lines of what I was thinking. I can set the Victron a target to charge to, say 100% with a charge window of 02:00 - 16:00, it will not discharge the battery during that window. It will easily charge to 100% by 5am, so all solar will then go to running the house and the excess is exported at 25.53p per kWh. Catch is if there is low solar production we'll be pulling units at 35.31p, but our usage prior to 16:00 is usually low around baseline of 500w, so it would only be peaks that come from the grid (kettle etc) if the solar is bad, even a bad day there is enough usually to cover base load.

We'd enter the 16:00 to 19:00 with a full 100% charge, and could discharge plenty in that time once I figure out how, just keep enough back to cover us through to 2AM

To min max it you’d need to be looking at it daily which is going to be quite a hassle.

I don't think so, as long as you don't want to squeeze every last penny out of it, there is no need to micro manage it.

 

[Welshman]

I dont have batteries, but i do know that for the last few days even with low production, we have been exporting betwen 4 and 6pm...as our base is so low

 

[HungryHippos]

To my mind, so long as the Flux export tariff is also running, it will always be worth charging in the 3 hour off-peak window, even in summer.

Pay 20p/kWh, and in the day export for excess solar is 24-25p/kWh back, it's only a few pence but both methods fill the battery. I can see no downside risk to charging in the off-peak window as solar won't be generating enough at 5AM to matter.

Exporting in the peak window is it's own question though, the rate is very good, but it's not much above the import rates in the core parts of the day. For me it's 34p/kWh for every unit I spend maintaining 100% battery for the export window, and then 38p/kWh for every unit I export, so not a huge delta here either.

Is it even worth exporting? that definitely adds wear on the battery. Importing off-peak is a no-brainer though.

 

[Ron-ski]

Currently my rates are as follows

Import

Flux rate 21.19p
Day rate 35.31p
Peak rate 49.44p

Export once live

Day rate 25.53p
Peak rate 40.36p

So if my battery is fully charged at the Flux rate, it costs 21.19p per unit, lets say its empty and I charge with 14.5 units, it costs £3 to charge it.
I then discharge 13 units (allowing for some efficiency losses) at peak rate, I get £5.24, a net gain of £2.24.
We then have an empty battery, so between 19:00 and 2am we import, which will be circa 7kWh at a cost of 35.31p per kW, so an actual cost of £2.47

But any excess solar is also exported during the day, which means net gains, and I think once I have the second battery, making a total theoretical capacity of 29kWh I'll easily be able to keep some back for the 19:00 to 02:00 period.

Working it out makes my head hurt, especially as you really need to take account of efficiency losses, also DOD discharge will mean we never charge a full 14.5kWh anyway.

I'm not too fussed about cycling the battery, my EVE cells should last for 6000 cycles, which at one cycle a day is circa 16 years.

One thing to remember with Flux is the prices are variable, and not fixed.

 

[HungryHippos]

Yes which is why I'm sure that the only real gain you can theoretically make is to charge the battery at flux rate and then play the arbitrage game of exporting it for more later, but that doesn't really take into account daily consumption as you go. You want as much in the battery as you can for exporting at the best rate you can get.

If you think about it, not worrying about the battery charge state after 19:00 may be best. Because dumping battery to grid fully by 19:00 will pay you 40.36 (my rate on this is only 38~ btw!) and then any subsequent units you use from grid will be 5p cheaper at 35p, a small gain again per kWh instead of letting it drain naturally from the battery.

I was trying make a similar of sorts for this in Excel. WIP.

 

[Welshman]

just had the confirmation email…..we are fluxing

 

[HungryHippos]

This is my sort of worse case scenario (battery 8.2kWH, 2.4kW charge/discharge rate, 1 kWh consumption per hour for background stuff, no solar).

This doesn't take into account efficiency loss of storing kWh, or a more extreme usage scenario like using major appliances such as cooking or washing.

No Schedule could also be configured to hold a much lower SOC %, but you may as well drain it in a way.

With this model, ALL solar generation would be considered exported, so that cost per day of £6.63 is without any export calcs, if I exported 10 kWh in the day then it would reduce that by £2.44 (£0.244 * 10 kWH). I would need 27.17 kWh exported from solar to make the energy free for the day. Exported solar after 16:00 would have a higher value, so I'm again using worst case calc of regular daytime export rates.



This is the same thing but for Go. No Export listed as no point mentioning it really, it's too minor most of the time to bother, and there is no point doing forced discharge,

I've offset the start by 30 mins but 01:00 - 05:00 is 4 hours and isn't going to be miles off 00:30 - 04:30 for most of us.



Go is cheaper with no solar on the same usage basis at my current rates. I won't re-post a new image unless there is demand for it, it but if I do the new current Go rates (12p / 44p) then it seems to come out at a daily charge of £6.66, extremely close.

Factors in Go's favour is that it benefits a little more from the min/max arrangements, you don't really gain much on Flux for not charging, but Go allows you to be really efficient if you leave headroom for charging in the day and making the most of the generation as it comes in.

For Flux, any import at the peak rates are very punishing unit rates, but if you can avoid that, it seems you can be reasonably efficient still.

It's possible to get negative prices on the day with Flux with extremely good generation, but with Go the SEG is so poor that I think the best you can hope for is basically close to £0 on a day rather than negative.

I'll adjust the consumption down a bit on both and see how the usage compares.

 

[HungryHippos]

Sorry for spam but same figures with a few adjustments to format, and with a lower consumption of 0.75 kWh every hour instead of 1 (which is closer to my actual).

Flux:



Go (current rates - edit yes I realise my export price here is £0.41 instead of £0.041 but it's not used for this anyway as no export!):



Eco 7:



So without any solar both are close still.

However with Go I think it's possible to do better with low solar than with Flux, which is why Go is still better than Flux for at least a few months of the year (estimate 5-6) but it's not as if it's earth shatteringly better.

Go also has a low cost if you can get just enough generation to tick you over, and in both cases you don't really export anything.

 

[Freefaller]

Amazing! Lots to digest but all take a look more closely.

We're fluxed up now as well.

Based on my initial sums and usage it makes a lot of sense for us.

 

[Welshman]

Amazing! Lots to digest but all take a look more closely.

We're fluxed up now as well.

Based on my initial sums and usage it makes a lot of sense for us.

Same…….been exporting all day here

 

[Ron-ski]

@Freefaller and @Welshman Are you also on Flux export? Only showing import on my account, although I think you both may have been exporting with Octopus already.

 

[Freefaller]

@Freefaller and @Welshman Are you also on Flux export? Only showing import on my account, although I think you both may have been exporting with Octopus already.

No only import for now. I guess export will take a bit longer to sort out?

 

[Ron-ski]

Seems that way.

 

[Welshman]

Seems that way.

Yup just the import for me…..but already exporting at 15p for now

 

[HungryHippos]

I added Eco 7 in my post above as well, with a guess at a 7 hour window from 01:00 - 08:00 and assuming no strange usage or solar generation as it exits.

Surprisingly, without any solar at all, it predicts that the cost could even be the same as Go, but with the caveat that this is my scenario more than whatever you guys may have.

But it does show that even if Octopus pull Go from people without EV's, there may be reasonable alternatives, either in Eco 7, Flux, or possibly even Agile if that gets good again.

Eco 7 has the benefit of allowing you to use the better SEG paying options as well, which I showed at normal Outgoing rate, £0.15/kWh.

I think I'd summarise things a bit like this personally:

• Flux - Good for the higher solar generation months. Can be set & forget rather than needing babysitting. Recommend charging in the 3 hour window no matter the weather or season.
• Go - Has the best potential to be cheap in the Winter months, but requires babysitting from Spring - Autumn to min/max the charge a little.
• Eco 7 - I actually like the 7 hour window here even if it's 16p/kWh vs 12p/kWh on standard Go, that is 3 less hours you need the battery to cover in the day, which is why it can make up the difference with Go on a no-solar day.

My Go tariff runs until September at 7.5p/kWh off-peak and I think it will be hard to change to Flux before April in my case, as I will still be heavily reliant on it until then, especially if this weather holds up.

I may try and add in an assumed solar generation as well on each of these see what the differences look like. A job for another time though.

 

[casper_uk]

How did you get onto the flux tariff? I registered my interest, but haven't heard anything from Octopus yet.

 

[Ron-ski]

https://octopus.energy/smart/flux/ and there should be a sign up link on that page.

 

[Freefaller]

Interestingly I set up my GE to charge last night but it didn't (via the GE app not HA) - so not sure exactly why that didn't work.

 

[SBo]

Looking at the Agile price movements, Flux’s rates may change a lot over in the near future- makes it really hard to judge if the move is worth it.

As an EV and solar/battery owner I am staying on 7.5p off peak Octopus GO and BG 6.4p export for the time being for the certainty, but watching how you get on with interest.