FoxESS Community - Owners & Installers Forum

Hello experts.
I’m on Octoplus Flux and export power between 16:00 and 19:00. During April, I’ve sold more kWh then I’ve bought so that good.
We installed the system in Jan and we were on Octoplus go until we got the certificates in March to export but I’m wondering if its best to move back to Go during winter because we can buy power far cheaper to charge the battery on Go than we can on flux. In Jan - March we charged the battery from 00:00 to 06:09 at 8.1p /khw. Used that during the day (16khw battery) plus what we had generated (6kw PV ) but we didn’t generated much more than we used.
On Flux, we buy for 14p between 02:00 and 05:00 but we can sell power back which you can’t do on Go.
So I’m wondering if people switch back to Go for winter or stay on Flux all year round. I’ve not done the maths to see which is better!!
Thanks for your insights

I've personally found that Go and being able to be fully charged overnight and exporting all my solar generation during the day is worth more to me and it's very kind on the batteries.

objohnuk@gmail.com wrote: Mon Apr 21, 2025 9:08 pm On Flux, we buy for 14p between 02:00 and 05:00 but we can sell power back which you can’t do on Go.

I believe that you can sell power back on Go for 15p/kWh, if you use the Octopus Fixed Export tariff. I'm not actually an Octopus customer so not sure what is involved with getting the Fixed Export tariff.

I'm on E-on Next Drive, which is 6.7p/kwh import between midnight and 7am, 25p/kWh for the rest of the day, and 16.5p/kWh flat rate export. I charge the battery overnight, run from solar & battery during the day (effective cost about 7.3p/kWh due to round-trip losses), using 'Feed-in First' mode in order to immediately export the solar without wasting 10% of it in the battery, and then finally I export at the end of the day to make use of the remaining battery surplus.

I’m newbie here, just had my solar+installed on Friday 25th April. How long does it take to receive the MCS certificate, etc?

How do I know if the firmware on Inverter is up to date ?
Where is firmware version written ?

How do I know if installers applied for G98 or 99 for export limit?

Would the installers apply for my export tariff or I have to do it myself ?

I’m on intelligent octopus Go at the moment;
Apart from force charging the battery simultaneously with charging EV, is there any setting on the App to prevent battery drain overnight during the off peak period?

Pitagor wrote: Sun Apr 27, 2025 10:42 am How do I know if the firmware on Inverter is up to date ?
Where is firmware version written ?

Look in the V2 app, click Device at the bottom and then click the Inverter and click on the serial number below the picture of the inverter, that will show your Master, Slave & ARM(Manager) versions - post them here and include your inverter model H series, KH series etc.. and I can check latest.

Pitagor wrote: Sun Apr 27, 2025 10:42 am How do I know if installers applied for G98 or 99 for export limit?

You really should know this in advance (speak to your installer and get them to confirm they have applied) as G98 can be applied for after install, G99 must be applied for and approved in advance - if your inverter is 3.68Kw or smaller you will be G98, any larger and it needs to be G99.

Pitagor wrote: Sun Apr 27, 2025 10:42 am Would the installers apply for my export tariff or I have to do it myself ?

It can take quite a few weeks when a G98 has been submitted before the DNO sends you your export MPAN, you then give that to Octopus and they can set you up with an export tariff - you could try specking to Octopus whilst you are waiting as they may be able to do this for you.

With G99 it must be applied for 30 days in advance of the installation, and the DNO will have provided the export MPAN when they approve the application.

With me, it was about 2 weeks for the MCS and so forth, and another week for the export MPAN. The installers applied for the export MPAN so I didn't need to wait for E-on to do it (otherwise it could have been weeks later).

With Octopus, they will only pay you for export from the time that the smart meter starts returning data (which may be a while, since they need to wait for the export MPAN from the DNO).

With E-on, they pay you based on the photo of the smart meter's export register, at the time that you applied for a SEG account (which I did as soon as I received the MCS etc, so prior to the export MPAN).


The rates I get from E-on are:

Drive import tariff

* 6.7p/kWh midnight to 7am (so I fill up the battery from that, and that'll last me all day without having to use the rate power)
* 25p/kWh for the rest of the day

Export tariff

* 16.5p/kWh flat rate export

The advantage of E-on is that the rates are pretty good compared to Octopus, and they pay you for the initial generation.

The advantage of Octopus is that you get the extra charging periods from 'intelligent', and it is easier to swap between tariffs at different times of the year, if for example one tariff is better in mid-summer, and another tariff better in winter, and also they use the smart meter rather than relying on photos of your meter 4x per year.

That’s the details of my inverter , please and confirm if firmware is up to date.

These are the latest versions for your inverter, you are a little bit behind - either ask your installer to update or you can raise a support ticket on Fox in the app

Master 1.33,
Slave 1.03,
ARM(Manager) 1.49

Thanks Dave, I’m raising a ticket now for firmware to be updated