Optimising My Solar Export - Getting The Most From Octopus Flux
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- เผยแพร่เมื่อ 9 ก.พ. 2025
- How we're maximising our solar export so that we get the most from the Octopus Flux tariff. See how we can increase our total export value by 20 to 30% yet stay within the constraints of our relatively smallish battery setup.
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I haven't worked it out, but a consideration would also be that the benefits of forcing the battery to discharge, would be outweighed by the damage you would do to the battery and reducing its charging cycles and life span, meaning money would need to be spent on a new battery.
Yes, that's definitely a valid consideration. I did see a video - can't remember who by - where they went into the economics of this... We've ended up not doing a huge amount of exporting so far during the peak evening rate due to a change in our consumption patterns. Will be re-assessing in the new few weeks as we start to go into the better weather (hopefully!). Cheers
This is my method as well Chris. Presently discharging the battery between 5-7pm on a daily basis. Seems to be working well. 👍
Cheers Dan.
Meant to ask ... can you set this up through your app?
@@handyman-at-home Not at the moment no. I just have a reminder on my phone each day and only takes a few seconds to do. Apparently GivEnergy are working on implementing it in the app though.
A very informative video … thank you.
Thanks
Just had a solar/battery installation a few days ago, thanks for the info, v helpful
Thanks!
Thanks for sharing just on Flux
Exporting more than i am using
Thanks - sounds good. In April I was roughly equal between export and grid import. For May, it looks like my export will be around 10% more than grid import. However, the real kicker is that May's PV yield is massively down on last year ... around 400 kWh as compared to 600 kWh last year - a drop of around 35%. Chris
Interesting and definite food for thought. Thanks for walking through your thought process.
We have 10.4kW of panels, 13.5kW of GivEnergy batteries, 2x Gen1 GE 5kW inverters, and moved to flux about a month ago but are still waiting for our export MPAN to be setup before we start getting paid for export. Annoying watching all the free energy go out at the momment.
I’ve been playing with ‘Gary does solar’s solar model and my own spreadsheet to plan what my flux strategy will be, so this video is another useful input, I certainly hadn’t thought of delaying the start of the force discharge. On Gary’s model, force export for 1 hour from 6pm will yield 40p/day extra income for me.
I was a bit confused by why you wouldn’t discharge below 20% and why you were worried about paying for grid import in the evening. My thinking was that you get a better export payment in the flux peak, and if there’s a bit of standard rate import afterwards, so be it, as long as its not import in the peak period. However looking at the rates I see that the peak export rate is (32.01p in SE UK) is only slightly higher than the standard day import rate (30.72p), but by the time you consider power loss through AC/DC energy conversion, its so close to be negligible benefit to export for longer.
So conversely I don’t believe there is any material benefit in charging the batteries overnight so you start exporting sooner. Looking at my flux rates, its 18.43p flux import rate and 19.72p day export rate - virtually the same. Indeed the Gary does solar model predicts for me that there’s only 15p a day extra benefit. Adds up over the month I suppose but not going to retire on it.
I feel your pain with waiting for the MPAN to be setup - in an earlier video I recount the struggle I had .... took nearly six months due to one reason or another. Yes, I'd spent some time with an early version of Gary's model - although I see he's made a variety of developments since I last used it. Delaying the force discharge towards the back end of the time slot wasn't something I'd thought of at all until I started putting the video together 🤦♂️ As regards the 20% discharge limit ... this was in part the default setting for my inverter, although it is easy enough to change it, and also I'd read a couple of articles/posts/blogs which implied it wasn't a good idea to fully discharge your batteries, as this could impact their lifetime. How accurate that is I don't know, but I decided to stay on the safe side. As regards not paying for import in the evening to re-charge after a forced discharge .... that was just a straight up cock-up! I'd somehow confused the rates in my mind and it wasn't until topbrands (comment below) highlighted this that I realised ... hey ho. More generally, I think you've highlighted a good point regarding the relative difference in rates, something which I think has now been exacerbated by the recent tariff changes brought into effect by octopus from 1-July. In my area, there's now only a 1.4p/kWh difference between Peak rate export and Day rate import, so I'd totally agree that there's no point force discharging IF you then need to import again at the Day rate. Now, if you've got a big enough battery to get you through the evening and early morning to the next Flux period, then the differential becomes 13.9p/kWh, if you can delay your re-charge until then. So, I think it echoes other posts which are of the view that the tariff works best if you have a larger storage capacity. Cheers, Chris
@@handyman-at-home Thanks for your comprehensive reply. These ‘more advanced’ tarrifs give lots of potential options, but more complexity trying to work out the best way to use them, but I guess that’s part of the fun!
Using your strategy I think I can afford to discharge about 3kW at the peak rate as my battery typically goes down to 40% overnight. I previously done some spreadsheet modelling of the benefits or not of getting more battery storage, and annoyingly the sums just don’t add up with payback of the order of 20 years or so. First views of Gary’s model comes up with similar conclusions, but I need to look at it further.
20% min discharge level is not great, that really surprised me. My GivEnergy batteries are 4% reserved and the newer largest 9.5kW batteries have 100% DoD as the actual storage capacity is higher than 9.5 its advertised as, so you do get the whole 9.5 as usable. Marketing ! Cheers Geoffrey
interesting video i have a 25kw battery home built and at moment looking into flux as at moment my export with FITT is becoming very uncompetitive.I have a 5.2kw solar array that at moment exports between 25/35kw on good day .My interest is in the cost/benifitt to charge solar only and import at low rate you vid gives some handy insights into this thanks.
Thanks! When you say you have a home built battery, can you give any details? Cheers
Thanks 🙏
Another great video 👍
Thanks 👍
The App is now out.
Hi, really interesting as only have a 5kwh battery. Noting Topbrands comments as well. Thanks.
Thanks
Can anyone tell me on the Flex where i can see my Exporting and how much i am making? Thanks.
I am switching to octopus soon as my contract ends. But I don't think I will force charge my battery at peak time. I have a feeling I will be better of preserving battery life.
Yes, it's an interesting issue - I haven't seen anything definitive one way or the other, so a cautious approach may well be sensible ... who knows! I've not read a huge amount about the new tariff variant that Octopus have started to push (Intelligent Flux) but I'm not convinced about giving a utility company control of my battery & inverter, no matter how progressive a company they might be. A watching brief for now I think... Cheers
I've just monitored our situation from a different perspective: "Can I reduce the importing on Flux?" I'm minimising the changes to the settings. Looking at three consecutive days generating different amounts of solar power I'm happy importing during the cheap period but only up to 25% SoC to cover our morning usage. Previously 20%. Why did you choose 100%?
I'm also charging in the hour prior to the peak period in order to ensure there is sufficient SoC for our evening and overnight usage. This is to the same percentage as the system can't have different settings.
Most of our export is due to the battery being full and the import is due to the maximum battery inverter being limited to 2.3kW, the 8kW shower will therefore always need 5kw import (about 0.22kWHr). This limitation is fixed even if we get an additional battery.
I assume all Flux users have now received an email about the export price being reduced in line with the reduction in the import price.
Luckily I have remote control, getting the loft ladder down every time to visit the system to alter the settings would be a real pain!
Hi Robert, I went with 100% primarily so that I would start exporting back as soon as there was any appreciable levels of sunshine in the morning; it does mean the first few kWh exported are technically only worth the difference between the import and export rates, but it should all work out more advantageous overall. Having the battery fully charged means it also covers initial use around breakfast time - although that's really only the kettle as we have a gas boiler for the hot water. Definitely agree with you on getting the loft ladder down - my installer was initially suggesting we have our system installed in the loft but I wanted it in the garage, which for us has proved the right decision. Jealous about the remote control facility though - what system do you have? Chris PS. Yes, have had the new rates email from Octopus, but haven't looked at it in detail as yet.
Home Assistant would work in this scenario. If you considered what battery SOC you wanted at the end of the peak period, say 30% and your battery was 50% you could discharge 20% If you knew how long it would take to discharge 20% (let's say 1hr), you subtract that time from your end time 7pm gives you 6pm to start discharging. This would stop you having to worry about predicting. Also I'm considering charging to full during the off peak period, as it's fractionally better return to export all the solar I can during the day. My install is in 2 weeks 🙂
Good luck with the install - hope it goes smoothly. Have seen a couple of videos about integrating a Solis inverter into Home Assistant, and that is notionally on the list for my development plan .... but much to do before we get to that point I think 🤣. Cheers
For me I prefer not importing anything from the grid therefore my import is only about 8kw pm, by midday the water is hot and the battery fully charged, I would then force discharge any surplus energy in the evening down to 50%
Yes, it feels a bit counter-intuitive to import power only to export it again, but I guess that's what they want us to do having created these 'Smart' tariffs - I suppose it's a function of how the electricity market pricing operates ... low demand, low price - high demand, high price etc. Cheers
@@handyman-at-home Time-shifting is useful for helping to balance the grid even for those who can't generate their own electricity.
This Month Exported 531.20 kWh
Import / Used 473.73kWh. ? On flux cost £126. 94 ?
That's a hell of an export figure... What size panel array do you have?
Thanks for thie video. I am looking to move to flux when my Octopus Tesla plan expires in October. My plan is to max charge during off-peak then discharge during flux, and I suppose the main challenge is to minimise high consumption appliances during the flux period. I have a couple of questions - how do you control the import/export schedule? Is it using the inverter app? I have a powerwall so I assume the tesla app will change to allow this. Also, if I am charging at 5kW max rate duing low peak time (should take nearly full period), should I be able to also charge my EV simultaneously? I can't see why I wouldn't. This would increase benefits of the tariff if I could import more at the lower rate. Thanks again for the info.
Thanks for the feedback. You're spot on - the challenge is to minimise high consumption during the peak rate period between 4pm and 7pm. We were doing pretty well at this but more recently, due to a change in work patterns, we've started eating a little bit earlier in the evening, meaning we sometimes have the oven on during the peak rate slot. It's not a disaster, because it draws mostly from the battery, but we're not quite getting as much benefit as before. Not going to worry about it though 😎
The only way I can control the import / export schedule is via the front panel on my Solis Hybrid inverter; unfortunately the SolisCloud app does not provide this capability. I understand the GivEnergy app does have this capability, but don't know about Tesla. It's not a massive disadvantage having to set it manually, as I've just left it set for the last few months. That might change as we get into the autumn and winter months though.
I'm not upto speed with EV charging - still a petrolhead - but I can't see why you couldn't charge your EV simultaneously - I presume it would be on a different charger than anything to do with your solar system?? Only possible problem I could think of would be if you popped the main incoming fuse to your property, by drawing more than 100A ...! But I doubt that myself 🤞
Last thought ... would Octopus Go not be better suited if you have an EV? Not sure how it compares to Octopus FLux.
You exported energy not power
does your system have the option of something like "everyday 5-6pm {or what ever time you get the maximum price}, export/sell until the battery reaches 52%"
Now that'd be a really useful feature 👍 but I haven't seen anything like it so far. The ideal would be to have this sort of advanced functionality incorporated into the app, but mine (SolisCloud) seems mainly oriented towards reporting information, rather than giving the user control. Will keep looking .....
@@handyman-at-home It does seem a rather basic requirement, even Luxpower can do that!
Do you have an export limit set by your DNO?
Hi, My system (like a lot in the UK) is classed as a single phase micro generation G98 installation - see connections.nationalgrid.co.uk/get-connected/solar-and-wind/micro-generation-single-g98/
which limits the output to 16A per phase. As far as I know, there's no other limit to how much I can export
Hope that helps answer your question? Cheers, Chris
Hi cris can you tell me when octopus pays for exporting energy thank you
Hi, Not sure I fully understand your question but perhaps this helps ... Until the start of May, I was on a flat rate export tariff with Octopus, where they paid 15p/kWh whatever time of the day or night you exported. The Octopus Flux tariff that I'm on now basically has three rates - a Flux (low) rate between 02:00 and 05:00, a Peak (high) rate between 16:00 and 19:00, and a Day rate for the rest of the time. The exact rate varies slightly depending on where you are in the UK. Cheers
just started doing this.. seems to be the month after.
Chris
I think your base assumption of do NOT import electric in the evening is not correct.
You will be importing electric to replace the electric you exported in the peak period.
Since the export price at peak is always greater than the import price in the evening then it is not a constraint.
You are leaving money on the table.
Cheers
Tim
Hi Tim, Good spot. Of course - you're right. I can only think I've misread the two rates and then convinced myself they were the same ... 🤦♂️ At least it doesn't amount to a huge amount in my case ... I reckon under £3 a month by my calcs. But with a larger battery it would certainly be more. Looks like I'm going to have to change the vid title to "(Almost) Getting The Most ...." 😂. Cheers, Chris 👍
@@handyman-at-home given this, it is a set and forget for the next few months.. No need to adapt daily for weather forecast
@@TimWigan Hi, good point. However concerned whether wearing out the battery by having more cycles.
Wear out in my mind is 80% capacity after 10 years and not scrappage. At this point I will buy another battery to replace the lost 20%. My view is that this strategy will not make a material difference to the 20% capacity loss but may make a slight loss.
On balance I am doing it...😁
You are right Chris. I was going to say the same thing. It is always optimal to force discharge as low as safe for the battery during the 4-7pm slot. Just be careful not to import during that period. Furthermore you should always force charge during the overnight 2-5am slot. If the batteries reach 100% during the day and you have to export you still get more for it than you pay to import during the night. You will be able to discharge anything remaining during the evening slot, so it is possible to make money even during the winter when there is little or no solar. That is how the Flux tariff is setup to work. It is always optimal to fully charge 2-5pm and discharge 4-7pm. Octopus pay us to be their storage provider as well as their solar power station.