How to getthe best out of Octopus Flux

bigmike20vt said:
your solar system and battery is v similar to mine and i am really pleased with Flux since joining. IF you didnt have PV or battery those prices look decent.

but imo it is hard to consider anyone other than octopus if you have panels &/or battery. just remember to get a referal off a friend , family or forum member . that £50 octopus credit will cover your leaving cost.

it may be work keeping your gas till it runs out however.
Click to expand...
Thanks @bigmike20vt - Just waiting to hear from BG if I can remain with them as a gas supplier. Should that be the case, it's a no brainer. Even so - the central heating won't see much if any use between now and Oct. Just the combi firing for on demand hot water.

Thanks again.
 
grantgam said:
Thanks @bigmike20vt - Just waiting to hear from BG if I can remain with them as a gas supplier. Should that be the case, it's a no brainer. Even so - the central heating won't see much if any use between now and Oct. Just the combi firing for on demand hot water.

Thanks again.
Click to expand...

Even if you can't stay with them for gas, if you don't use much in the summer due to combi, costs won't be much different ahead of October anyway.

Octopus has a tracker for gas you can join the queue for, and by the time October rolls around you'd likely be able to join it.

You can get onto Octopus pretty quick and be on Flux import fairly soon as well, which would allow you to charge at 20p overnight, even if export isn't ready immediately, your unit costs won't skyrocket thanks to cheap overnight and solar.
 
HungryHippos said:
Even if you can't stay with them for gas, if you don't use much in the summer due to combi, costs won't be much different ahead of October anyway.

Octopus has a tracker for gas you can join the queue for, and by the time October rolls around you'd likely be able to join it.

You can get onto Octopus pretty quick and be on Flux import fairly soon as well, which would allow you to charge at 20p overnight, even if export isn't ready immediately, your unit costs won't skyrocket thanks to cheap overnight and solar.
Click to expand...
Can stay with BG for gas, so that's a small saving anyhow for ~6m.

Electricity switch scheduled for the 4th, albeit they can't find my Import MPAN or meter serial... I've sent them billing confirmation and a photo of the meter. Hopefully a straightforward thing their end to update manually.

With regards to cheaper 0200-0500 rates, does it really make all that much sense to charge the batteries from this lower cost? I'm trying to work out if importing to export is worthwhile given such a small difference between the two prices (<2p)? There's SOC as a variable that I can't quite work into the maths i.e. if the batteries are fully charged by 0230, I'll essentially still be drawing from the grid for 2.5 hours to maintain 100% SOC without any real benefit?

As it's a matter of pennies, just coming to wonder should I just let solar top the batteries up before exporting as normal? Photo shows 100% SOC after just 90 minutes.


​
 
Last edited:
grantgam said:
With regards to cheaper 0200-0500 rates, does it really make all that much sense to charge the batteries from this lower cost? I'm trying to work out if importing to export is worthwhile given such a small difference between the two prices (<2p)? There's SOC as a variable that I can't quite work into the maths i.e. if the batteries are fully charged by 0230, I'll essentially still be drawing from the grid for 2.5 hours to maintain 100% SOC without any real benefit?
Click to expand...

The answer for this is... depends!

For me, yes, without a doubt I should charge the battery 02:00 - 05:00. The answer for this is considering best and worst case scenarios.

Worst case scenario:

What if it's cloudy/rainy and I don't generate much solar that day?

The overnight charge guarantees me some cheaper units to use, and means I am less likely to need the grid at peak.

Best case scenario:

It's really sunny and battery remains full most of the day?

No big deal, any excess units just get exported. I pay £0.20 per kWh to fill the battery, I get £0.24 per exported daytime unit. I am not really better or worse off after considering losses of efficiency from converting AC to DC in the battery, in both cases the battery would get filled.

Essentially it's a zero thinking required, no hassle approach to ensuring a local energy supply is available, and the upsides outweigh the downsides as I see it. That knowledge I will have a minimum commit of available power is worth more than slight efficiency losses in charging the battery.

The only scenario I can think of where this may not be as good, is if your solar clips when the battery is full, I've seen some people report that. I don't have this issue as my inverter is 5kW and can export every kWh I generate without clipping. For people with this scenario it's not going to be as efficient as the excess solar gets lost rather than used.

If you're not getting paid Flux export then of course that is also going to adjust your charge behavior, as you would not get paid for excess, but I am assuming you are not including that in your query.

My ethos with Flux is that I am fully intending to charge the battery, and end the day with a discharged battery, a lot of the time this is 1 charge cycle per day.

02:00 - 05:00 - Charge the battery as much as possible.
15:00 - 16:00 - No specific instruction
16:00 - 19:00 - Discharge the battery to home (optional - Export excess power down to a certain SOC %).
19:00 - 02:00 - No specific instruction

Although having used this for a week or so I am thinking of extending the discharge slot in the evening from 16:00 - 19:00 to 16:00 - 23:00. This will pause any battery charging after 16:00 and send all excess power to to the grid, most of which I aim to do between 16:00 - 19:00 for the peak export rates.
 
Last edited:
Thanks very much for the detailed reply @HungryHippos.

It would seem like a no brainer to charge 0200-0500 then, there aren't really any draw backs as you've said. Cloudy or sunny.

HungryHippos said:
The only scenario I can think of where this may not be as good, is if your solar clips when the battery is full, I've seen some people report that. I don't have this issue as my inverter is 5kW and can export every kWh I generate without clipping. For people with this scenario it's not going to be as efficient as the excess solar gets lost rather than used.
Click to expand...

With regards to the clipping, I can see that my system clips at 3.8kW. In my mind, this makes sense given it's a 3.6kW inverter. As I understand it, the inverter is limiting what power is drawn from the panels to fall within its rating. Which aspect of clipping are you talking about being not as good?


HungryHippos said:
My ethos with Flux is that I am fully intending to charge the battery, and end the day with a discharged battery, a lot of the time this is 1 charge cycle per day.

02:00 - 05:00 - Charge the battery as much as possible.
15:00 - 16:00 - No specific instruction
16:00 - 19:00 - Discharge the battery to home (optional - Export excess power down to a certain SOC %).
19:00 - 02:00 - No specific instruction

Although having used this for a week or so I am thinking of extending the discharge slot in the evening from 16:00 - 19:00 to 16:00 - 23:00. This will pause any battery charging after 16:00 and send all excess power to to the grid, most of which I aim to do between 16:00 - 19:00 for the peak export rates.
Click to expand...

I'm yet to consider brown energy exporting, at the time of my installation (04/22) everything I read said that brown export was a no-go. This was all with respect to SEG payments mind you, is Octopus exempt from this as it's not technically SEG with it being an in house arrangement?

Thanks again!
 
Last edited:
grantgam said:
With regards to the clipping, I can see that my system clips at 3.8kW. In my mind, this makes sense given it's a 3.6kW inverter. As I understand it, the inverter is limiting what power is drawn from the panels to fall within its rating. Which aspect of clipping are you talking about being not as good?
Click to expand...

As I understand it some inverters are limited to say 3.6kW but can exceed that if the battery isn't fully charged up, once the battery is full they clip again at the top end like your 3.8kW figure shown.

This will vary by system, but any systems that do that, may still want to charge a bit, but may want to leave some headroom for solar to battery as it's more efficient.

I am not sure if this is true for your system or not, mine is just limited to 5kW load regardless it seems, which is fine as my panels are 4.8kW and the inverter is 5kW.

grantgam said:
I'm yet to consider brown energy exporting, at the time of my installation (04/22) everything I read said that brown export was a no-go. This was all with respect to SEG payments mind you, is Octopus exempt from this as it's not technically SEG with it being an in house arrangement?
Click to expand...

I've yet to see Octopus dissuade people from doing it, though you are right some SEG providers dislike it.

With Octopus and Flux though, you can't really arbitrage that well unless you have massive battery storage and a lot of throughput on the inverter. Even then, buying that just for this reason isn't a good one alone.

Buying at £0.34 to sell at £0.36 isn't worth it, so the main gap is the cheaper import at £0.20 and then the later export at £0.36, something which you can only really do if you've had a good day for solar anyway.

I don't really see it a huge deal as I'm providing extra kWh's to the grid at the peak of the usage, so every kWh I send out at that time is helping keep the grid balanced and reducing carbon usage. My battery export rate is limited to 2.6kW and not all of it will make it out, there are losses in efficiency at max export.

I can almost drain the battery from 100% to 0% in 3 hours, but not quite, and frankly that doesn't make sense either as I still need power until 02:00, and there isn't much point to exporting at £0.36, to then buy again after peak at £0.34.

My half-way meeting design is that I export down to around 65% SOC (8.2kWh battery) in the peak window, and store the rest to see me through until 02:00. This will again vary person to person, and by house demand etc.
 
Last edited:
I basically do the same as above:

  1. Charge battery off peak (maximum charge circa 24kWh, 8kw x 3 hours)
  2. Solar tops battery up to full - capacity circa 14.5 kWh
  3. Excess is exported at more than we paid per kWh to charge the battery
  4. Discharge some at peak rate down to 65% SOC, but keep some back to see us through to 2am and in case of a power cut.
  5. Repeat the above.

I currently only have 14.5kWh of battery, but in a couple of weeks will have another battery, so will have circa 29 kWh of storage, and will lower the target SOC to reflect that.
 
Thanks @HungryHippos and @Ron-ski - appreciate the input.

Will hopefully be migrated to Octopus flexible on or around the 4th and then (hopefully) Flux a short while later.

I think I'll leave the battery exporting aspect out of the equation for the time being, will be in a better position to judge once I've seen the data.
 
Still undecided if I should join flux, only had the system since just before winter and the go tariff saved a lot on money. As I haven’t had a full year yet not sure of the gains over the summer will counteract the cost increases in the winter considering I can’t force export my batteries.
 
Last edited:
It does depend on your situation. For us it's a no brainer. April we made money and will make money till probably October. Nov-march we've halved our electricity bills at least. I means I am more comfortable having the heating on and it offsets the cost of gas.

But we don't and won't have an electric car so that's also something to think about.
 
Last edited:
redfist said:
Still undecided if I should join flux, only had the system since just before winter and the go tariff saved a lot on money. As I haven’t had a full year yet not sure of the gains over the summer will counteract the cost increases in the winter considering I can’t force export my batteries.
Click to expand...

I've found it better in that it's more of a plug and forget solution.

No more trying to use excess solar to avoid getting paid a pittance. They owe me a quid in the last week with SC included and having charged by car

Sure it's not going to be as good come Oct but will cross that bridge then. Rates are likely to be different then anyhow
 
indeed I left octopus Go faster on 24th April onto Flux. (no EV yet) and it's looking like it is going to be a huge win for us until start of October. By then I do hope to have an EV which will of course change the calculation again. I will likely join IO then. (until that point I will mostly charge my car at work if we get an EV before then I suspect as they only charge 14p/kWh). whilst this is more than IO or Go , I think exporting my excess on Flux prices will more than cover that increased cost through summer.
iirc it's moot for me anyway as whilst octopus don't lock you in as such I don't think they let you flip flop between their beta packagers more than every 6 months
 
Last edited:
Data from when I joined Flux 20/04 until today, so far looks like it's around -£20 + whatever I export today.

Pretty happy with that. Will be interesting to see how much extra generation I get in the next few months, as well as how much energy I need to spend on cooling instead of exporting in the summer.

pzMGDVn.png
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom