How to getthe best out of Octopus Flux

HogPower · 20 Mar 2023 at 23:44

Newbie - P/Wall 2 + 12 Maxeon 375 (all SSW facing) + solarEdge + Tesla Gateway 2 (no EV). Commissioned mid Jan.
I'm interested to know if any Powerwall (PW2) users have actually moved onto FLUX since it went live and what their experience so far is?
Reason being - I don't think (from what I've seen in other forums) that PW2 owners have any control over direct export from their PW2 to grid - at all.
Speaking to Tesla support, their message is - no you can't force export or control if, how or when your PW2 discharges to grid - only your energy supplier and/orTesla can do that.
So unless I'm missing something here - the only way Im allowed to export is when there is excess solar (PV output>(battery demand+home demand)).
My NG commissioning doc states - '3.68kW PV and battery storage 5kW set to zero export'. I asked my installer about this and they confirmed that any export to grid will come only from solar excess and that at present the battery can never discharge to grid, and peak solar export to grid is inverter-limited to 3.68kW, but peak battery output (for home consumption only) is 5kW continuous.
I've emailed Octopus to see what their views are and I'm still waiting for a reply.
So for me, it seems that even with my PW2 100% charged and ready to rock its 13.5kWh, and 0kW home usage, I still can't take advantage of FLUX peak export rates unless the sun is shining....
At the moment I'm on Octopus Flexible Tariff (flat rate), so on sunny Saturday the PW2 hit 100% soon after lunch, after which the Tesla app began reporting up to 3.2kW export to grid - my good deed for the day....
I'm hoping to get going with FLUX soon - but obviously I'm aiming to optimise avoided costs of import + export earnings so I can reduce the payback period (currently 12 years) for what has been a pretty expensive investment!
Apologies if I've missed something obvious (should have gone to SpecSavers comments aside - I'm stuck with Tesla now!).

HungryHippos · 21 Mar 2023 at 09:30

Well that sucks, as you paid all that money for a Tesla battery you can't fully control.

One of the reasons I didn't go with Tesla, I figured my options were limited, and to make the most of it you only had one option, the Tesla Energy plan via Octopus.

Ron-ski · 21 Mar 2023 at 15:53

@HogPower I believe the Powerwall can be set to discharge to the grid, see this thread.

myenergi-Tesla Powerwall configured for Export?

Does anyone have a Powerwall 2 which has been configured to enable manual export of power? Looking at Octopus Outgoing Agile for my SEG tariff and the

myenergi.info

I suspect your installer has disabled the option because they only applied for a G98, which only allows for 3.68kW maximum export.

You could contact your DNO and ask if you could export more, you'd need to check what the maximum power the Powerwall can supply, and then add the 3.68 of the PV inverter to it, it's this figure that the DNO will require.

If they say yes, you'll need to apply for a G99, and convince your installer to unlock the feature.

With regards to the DNO they may not be too helpful at first, and just say fill out the forms, this is the first response I got, but in the end I did get more info.

HogPower · 22 Mar 2023 at 00:09

Thanks for your advice Ron-Ski.

I did see the link you mention, and I raised my concerns withn my installer about the 0kW Powerwall battery export in the National Grid acknowledgement of commissioning letter (it was a G99 application incidentally).

My installer sent me a copy of the email dialogue between them and NG regarding the G99 commissioning, and it's somewhat odd.
NG asked the installer to limit the battery storage to 3.68kW export and resend the G99 paperwork.
The installer replied asking Grid - can the customer not have 3.68kW inverter and 5kW battery with battery set to 0 export?
Grid replied sying - the customer can have 3.68kW on the solar but just the Tesla battery needs to be limited to 3.68kW export.
Eventually, they settled on 3.68kW solar export, 0kW battery export to grid, with max 5kW battery to home discharge (despite NG's comment that - some ask for export on the battery storage, but yes 0kW is fine.) - I had no say in this either.
I think you're right - it's down to the installer to sort out the confusion between limiting the battery export to grid and limiting the discharge to home.
What's the best way to sort this out in your experience - I'd be quite happy with a 3.68kW solar export to grid limit + 3.68kW battery export to grid limit (total allowed export to grid limit 7.36kW) - which is what NG seemed to be telling the installer to commission in the first place?

Ron-ski · 22 Mar 2023 at 13:26

@HogPower My experience is limited to my own installation, and what I've read on forums. It does sound very much like NG was saying a total export capability of 7.36kW was acceptable. Do you have an email address on the correspondence you received from NG. If so I'd email them along with property details, and any reference numbers and ask them, if they say that's fine then you'd need to tackle your installer.

Hopefully the system is clever enough just to set total export to 7.36kW, whether that's from solar, battery or combination of the two.

HogPower · 22 Mar 2023 at 14:09

Ron-ski said:
@HogPower My experience is limited to my own installation, and what I've read on forums. It does sound very much like NG was saying a total export capability of 7.36kW was acceptable. Do you have an email address on the correspondence you received from NG. If so I'd email them along with property details, and any reference numbers and ask them, if they say that's fine then you'd need to tackle your installer.

Hopefully the system is clever enough just to set total export to 7.36kW, whether that's from solar, battery or combination of the two.

Thanks again Ron-ski - I'll update if I get anything useful from contacting NG.
I switched to Octopus Flux tariff online yesterday and they shifted me on the Flux Import tariff almost immediately. Pretty straightforward process.
Obviously my smart meter still thinks I'm on Flexible flat rate, but the Tesla app showed the PW 33% charged going into the off-peak at 2:00am today, and then taking a steady 4.2kW grid off-peak import back up to 88% (not charging to 100% seems to be a common observation with other PW Flux users?).
PW SoC has remained steady throughout today at 88%, with 9kW of solar export to grid, peaking at 3.3kW export, so the PW already seems to be operating as expected.
I wonder whether Tesla might be working up an adaptive control system for PW charge/discharge strategy under the Flux tariff, using data collected from (maybe hundreds of) Octopus PW+Flux customers?

HungryHippos · 22 Mar 2023 at 14:16

If Tesla plan is ended they should be passing control back to you, or they can inadvertently wind up costing you money.

Mercenary Keyboard Warrior · 22 Mar 2023 at 14:31

Might be worth googling the default installer password, and if that doesn't work trying a few obvious ones, 0000, 1234 etc
I mean you shouldn't be going in and changing the settings but if the grid seemed to be giving permission for 3.68 export from your battery then it couldn't hurt to set that

HogPower · 24 Mar 2023 at 13:27

Thanks to all for comments. Had terse replies from NG and Octopus today. Not a lot of help on offer either way.
NGO say - ask your installer to fit G100 ELS to keep the entire installation below 3.68kW.
Octopus just say they've looked into it and Powerwall owners CAN setup for direct export from Powerwall.
This would work similar to a regular export set up but instead need to be set up to export from the powerwall.
Tantamount to nothing really, with no hint of how I might actually do it - thanks for the fob-off Octopus.
I assume NG is implying that, since I already have G99 approval for max 3.68kW export (from solar only), I could ask the installer to set up a G100 Export Limitation Scheme for my installation.
This would allow up to 3.68kW export to grid from Powerwall, as well as up to 3.68kW solar, but with no increase in the overall export limit which stays at 3.68kW (ie: if both PV and battery are exporting, the total power out never exceeds 3.68kW). Am I right in thinking this?
If so, I suppose it's a small gain for me t get some available battery export, but it still imposes restrictions on maximising the full potential of my installation.
I wonder if the 3.68kW limit reflects a local transformer capacity shortfall?
I had a quick read through solarEdge inverter ELS documentation here: https://midsummerwholesale.co.uk/pdfs/solaredge-g100-cert.pdf
and it says:
'The ELS may be programmed with a site export limit in kW and is set within a password protected menu to prevent
system owner override. The limit can also be set to zero, upon which the inverters output relays will open circuit the
inverter to give a true zero output. There is also the option to set P(V) limits should the DNO specifically request this
to prevent exported power above statutory voltage limits.'

Any advice for me before I start negotiations with my installer?

Ron-ski · 24 Mar 2023 at 15:47

@HogPower yes, as you already have permission to export a maximum of 3.68kW, you can do that all-day long, from PV or battery, or a combination of both, but not exceed it.

I would download form G99 and apply to add 5kW of AC connected battery to your existing 3.68kW export allowance, note on the form that the system is already installed but the battery is limited to zero export, but you'd like to have full export of 5kw from the battery as well, making a total of 8.68kW. They will then reply with an offer, and this will state whether anything needs upgrading and if so what it will cost, or they may just say yes that's fine, and then you just need fill out the relavant forms.

You haven't said who you DNO is, I'm presuming NG is national grid, but most DNOs don't charge for processing the form and producing an initial offer.

Once you know exactly what the DNO will allow, then tackle your installer.

HogPower · 24 Mar 2023 at 17:50

Ron-ski said:
@HogPower yes, as you already have permission to export a maximum of 3.68kW, you can do that all-day long, from PV or battery, or a combination of both, but not exceed it.

I would download form G99 and apply to add 5kW of AC connected battery to your existing 3.68kW export allowance, note on the form that the system is already installed but the battery is limited to zero export, but you'd like to have full export of 5kw from the battery as well, making a total of 8.68kW. They will then reply with an offer, and this will state whether anything needs upgrading and if so what it will cost, or they may just say yes that's fine, and then you just need fill out the relavant forms.

You haven't said who you DNO is, I'm presuming NG is national grid, but most DNOs don't charge for processing the form and producing an initial offer.

Once you know exactly what the DNO will allow, then tackle your installer.

Thanks again Ron-ski - DNO is Network Services (South West) / Distribution - Weston and Bath.
I assume the setting battery export to 0kW was done by the installer, but since the DNO already is asking for G100 ELS just to install the 3.68kW battery export option - won't this also apply to the G99 application for 3.68kW solar + full 5kw battery export?
I'll download the G99 now and get on the case....

Ron-ski · 24 Mar 2023 at 19:12

Yes, the battery export limitation was set by the installer.

I'm not entirely sure what the G100 is, but I believe it is where you have to limit the system to less than its capable of, and what you've said does fit with that understanding.

Everyone has the legal right to export up to 3.68kw, to do this you just need to inform the DNO once the system is commissioned, this is why a lot of Solar firms opt for this, its the easy route, and simpler. Anything more than 3.68kw and you have to apply for permission via G99, the DNO will check network capacity, and say yes that's OK, or set a limit of X, and tell you how much they'd like YOU to pay to upgrade THEIR network if you want the full allowance. Its a weird system, if your wanted to export 8.68kw and they said, unless you paid to upgrade the network, there nothing you can do unless you pay. But now if two of your neighboaurs also added 3.68kW systems, so another 7.36, whichs makes 11kw including yours, the DNO would be forced to pay to upgrade the network. However if you paid for the upgrade, and a neighbour then wanted to add a 5kW system, I believe you would get some money back.

I had a 4kw PV, with 3.68kw SolarEdge system installed in 2015, so I had an existing permission to export 3.86kw, last year I applied to add a further 8kw via the G99, and I was approved, no need for a G100 as I had full approval.

Its not clear from what you were told whether you simply can't add more, or they are just trying to tell you how to work with what you have, hence doing a G99 application, and seeing what they say.

HogPower · 25 Mar 2023 at 15:06

Many thanks Ron-ski - that's really helpful.
Having looked into the G100 ELS aspect, it depends on all the usual stuff, individual max rating of PV array output, PVinverter, battery rating limit, absolute limit on total amps going out at the grid connection point, and a requirement for a self-contained system (ELS) to continously limit the total export to either 3.68kW (SGI-1 and 2) or 7.36kW (SGI-3).
The bad news is that because my solarEdge inverter is the basic SE3680H, which combined with the Powerwall being AC-coupled (therefore having its own internal inverter), means anything over 3.68kW export will require additional hardware (eg: solarEdge StorEdge hybrid inverter at £2500 a pop...).
So instead, I'm going to go on the assumption that, as you say, I'm allowed by law to export up to 3.68kW from my generation installation under the existing G99 commissioning approval.
I also going to assume that the installer can remotely enable the Powerwall to export to grid up to 3.68kW, and the installer can also sort out setting up a G100-ELS-approved total export limit at the meter of 3.68kw (where potentially both the battery export + excess solar export could sum to 7.38kW).
From what I can tell this latter facility can be implemented by settings within the solarEdge SE3680H inverter, which has type-approved ELS capability to quash as much solar generation as needed to bring the meter at grid connection point down to the 3.68kW limit within 5 sec. (I've not been able to find out if the built-in Tesla Powerwall inverter can do the same trick with its own output). Again - hopefully remotely, and overall at no additional cost.
This gives me a bare minimum amount of export to grid from Powerwall, which is at least better than nothing (but not quite what you expect from "The Rolls-Royce of Battery Systems"...).
There's a niggle or two left to resolve - like - will this affect the Powerwall's peak home supply (currently I can draw up to 5A continuous) and its powercut backup operation - but I'm sure my installer can give me answers there.
So that's it - it's back to the installer to ask them to request a change to the existing G99 as above, then do the remote setup changes/testing for my installation after approval by the DNO.

All in all, a long road to get this far - but I agree with your comments about DNO infrastructure - the S West being out on a limb geographically has long suffered transmission issues (I used to work for the CEGB at Bristol) and a flaky local power distribution infrastructure, so I'm guessing that Portishead (which has doubled in size in 10 years) may now be in a dire state when it comes to hooking in new micro generation capacity.

Many thanks for everyone's input and advice - much appreciated. If I run into problems with my plan - I'll post again.

Ron-ski · 25 Mar 2023 at 15:43

@HogPower If you apply to your DNO for the full 8.68kW export and they approve it, then you don't need to limit anything, you'll just have to get the 0 export limit removed on the Tesla power wall.

If you don't get the export increased, then just get the Tesla to limit maximum export to 3.68kW, I doubt there is any need to touch the SolarEdge system.

PS Victron is the Rolls Royce of solar

HogPower · 27 Mar 2023 at 01:33

Ron-ski said:
@HogPower If you apply to your DNO for the full 8.68kW export and they approve it, then you don't need to limit anything, you'll just have to get the 0 export limit removed on the Tesla power wall.

If you don't get the export increased, then just get the Tesla to limit maximum export to 3.68kW, I doubt there is any need to touch the SolarEdge system.

PS Victron is the Rolls Royce of solar

Ron-ski - that's just the question I've asked my installer today. Keep you posted.

Ron-ski · 27 Mar 2023 at 06:35

@HogPower And you trust your installer, when they've already likely took the easy route? I did my own G99 application, even when I was getting quotes from installers, who all quoted for what they wanted, not what I wanted.

benbird7 · 28 Mar 2023 at 21:50

Ron-ski said:
@HogPower And you trust your installer, when they've already likely took the easy route? I did my own G99 application, even when I was getting quotes from installers, who all quoted for what they wanted, not what I wanted.

Just read through these last few posts, I'm getting 5.1kw of PV (13 panels@395 each) and a 10kw Huawei battery installed tomorrow, finishing the of the week.

The installer was proposing a g98 with Huawei 3.68kw invertor, but I considered the limitation on the potential peak, also considering the discharge of 5kw on the battery and asked them to submit a G99 and change to a 5kw invertor 5 weeks ago, this was accepted by UKPN and I have their letter confirming this.

My understanding this then allows maximum potential from the solar without clipping (I know undersizing invertors help when they isn't as much sun) but now can use the battery for the cheaper rate at night in the winter months when there's not as much sun.

I'm asking octopus to put me on the outgoing tariff as we approach better weather. I have a smets2 meter installed by them last August, will they need to change for me to get an export mpan?

My intention is to get familiarised with the system with a view to going onto flux Oct/Nov to use the cheaper night rate when my solar generation struggles.

Am I on the right tracks with my train of thought behind both these ideas?

Thank you.

Ron-ski · 28 Mar 2023 at 22:01

benbird7 said:
Am I on the right tracks with my train of thought behind both these ideas?

Yes you are, and no they won't need to change your meter, they will apply to UKPN for your export MPAN

HungryHippos · 28 Mar 2023 at 22:02

You'll need MCS cert and probably DNO paperwork to get your MPAN. I don't think both are necessarily available day 1.

benbird7 · 28 Mar 2023 at 22:05

HungryHippos said:
You'll need MCS cert and probably DNO paperwork to get your MPAN. I don't think both are necessarily available day 1.

Thanks for replies gives me some idea.

I've got dno paperwork, but if they need the mcs that will probably take a few weeks until registered and sent to me.