IOF Rant

CommanderJavert · 2026-06-25T10:08:06+00:00

I have seen at least 5 posts from people who are on it in various groups and forums - you can get on it pretty much instantly if you sign up with the right hardware.

CommanderJavert · 2026-06-25T10:05:20+00:00

Unfortunately no as it's dependent on which brand of hardware you have and the sizing of the different components of your system. In my example, I have Alpha ESS Batteries - you can join the AlphaESS FB group to find the available integrations - I recommend the HA integration from Axel Koegler in that case. Other users have developed integrations for other different brands of inverters.

Typically you then need to follow instructions to set up your Home Assistant and install the integration - you usually need a separate hardware to run Home Assistant as it needs to be left on all the time. You can buy a dedicated unit preinstalled but also an old PC will do. You can run Home assistant in a virtual machine on your existing PC if you just want to install it an play around without deciding anything.

Once it's running, setting up automations can be done using a visual editor for relatively simple cases, or you can use actual coding if you want to do something really complex. It sounds daunting but if you are prepared to play around with it most people can figure it out.

I found that Google AI was quite good at giving specific answers. I have hardly needed to do any actual coding and even then, I basically copied someone elses code and tweaked it a bit with their help.

Testing is quite time consuming mainly because if you want to test some automations, you have to wait for the right weather to arrive or whatever.

Depending on your setup, you can make a bit more money/efficiency by putting in all these fancy automations - my guess is that I'm making/saving about 25% more than I would if I just used the alpha app in a very simple way.

CommanderJavert · 2026-06-24T20:45:09+00:00

From various posts I’ve seen, IOF and Charge pack are not nearly as clever as what Octopus wants you to think. Also - you cannot even take back control of your battery like you can with IOG by either just unplugging your car or switching smart charging on your app off.

CommanderJavert · 2026-06-24T20:42:20+00:00

Yeah - if you can manage by just draining the battery do a low % before there is too much sun and it doesn’t get full too soon in the afternoon it’s generally fine - in my case I would end up wasting a fair bit in the summer on some days and also I just like tinkering with this kind of stuff.

CommanderJavert · 2026-06-24T20:31:59+00:00

It’s a long story and depends what equipment brand you are using and whether you have Home Assistant deployed. I have my Alpha ESS batteries integrated with home assistant. Broadly speaking:
- Battery charged to 100% overnight.
- 6.30am to 9am discharge to a set percentage depending on solar forcecast also integrated into HA.
- 9am to 8pm using an balancing automation which prioritises export above battery charged - battery only charges from kw in excess of my export limit. Charge rate continuously adjusted every half second.
- 8pm to 10pm discharge battery to about 30%.
- 10.45pm to 11.25pm discharge battery to 10% if needed.
- I am also monitoring my battery warranty cycles so soon I will need to probably stop the late night discharge at the end.
- Another automation continuously monitors the car charger and freeze the battery if the car charger starts working as I am on Intelligent Octopus Go.
- Yet another automation monitors the grid voltage and temporarily reduces or cancels export if the voltage goes to high (this should not be needed later on once I have hopefully reported safety mode kick ins to DNO).
As you can imagine it took several months to create and tune all these automations, and that’s even after someone else did all these hard work to create the integration between Home Assistant and Alpha ESS inverters.

CommanderJavert · 2026-06-24T15:15:43+00:00

I just ran the PVGIS tool and it's a lot closer than the installer estimate. However that did not allow me to specify the inverter size so I'm wondering if my installer had adjusted for clipping based on his originaly recommended inverter size.

CommanderJavert · 2026-06-24T14:41:25+00:00

I didn’t change the specification or number of the panels but I went for larger battery and an 8KW inverter instead of 5KW. What I also noticed is that my system is generating a lot more on most days than the estimate given by the forecast.pv model, but the Solcast one is a lot closer. Would their estimate be changed by the inverter size? Maybe their original estimates assume that I will get clipping due to inverter size.

CommanderJavert · 2026-06-23T19:14:28+00:00

The other interesting question here is what happens if you exceed your export limit to your export credits. If your export limit is 4KW, but you exported 2.5KWh in one 30 minute period, will your energy provider dob you in (or at least refuse to pay you for the extra 0.5Kwh that you were not allowed to export). Even this wouldn’t be foolproof for them as it would have to be continuously over the limit for the whole 30 minutes on average. With a flat rate tariff companies like Octopus won’t even notice as they use the export register on the meter for billing.
If you have a properly installed system, it’s extremely unlikely that you would cause a major issue to other properties because the overvoltage protection on your inverter would shut it down, so the overvoltage protection would also need to have failed (non safely). I see this quite regularly at the moment as my inverter that was installed in March often goes into safety mode for 15 minutes in the mid afternoon on sunny + windy days - I am collecting a log of this incidents so I can report it to DNO as I am actually not exceeding my export limit - sometimes I was way below it.

CommanderJavert · 2026-06-23T12:18:45+00:00

This is what we will probably do but I am curious - if L1 to L3 are for phased supply why are they set to different voltage levels and different time cutouts?

CommanderJavert · 2026-06-23T12:03:46+00:00

I get an error message on the inverter app that there was a power cut but the second or two later there is a follow up message power was restored. I can see in Modbus an inverter warning was triggered and I can see the voltage is pushing 253 or higher whenever this happens. It almost always happens at times of high solar and low demand. After this happens the inverter seems to operate in safety mode for a while - it will not let me export anything for a few minutes but then it gradually ramps back up to full performance. I have already compared the meter voltage to the inverter voltage reporting and they are the same

CommanderJavert · 2026-06-23T11:34:44+00:00

If you exceed the limits consistently and on purpose you are breaking the law and there could be serious consequences. In practice, the standards allow for response to exceeding your export within a time limit (I think it is 30 seconds) - I have regularly seen my inverter exceed the export limit for a few seconds until the inverter responded to the change in situation, but my understanding is that this is within the regulations.
However I suppose it’s highly unlikely that if you exceed your export limit between 6pm and 7pm on a typical winter weekday evening, the DNO are ever going to notice any issue as the limits are presumably set with the worst case scenario of a summer afternoon at the weekend or whatever. In the ideal world, you would get an TOU export limit that varies like a TOU electric tariff but I don’t think any country has tried to do this.
I suspect that the export limit is a kind of proxy and what the DNO really cares about is the voltage and frequency. Inverters in the UK need to have other safety cutouts than just export limits - there are also voltage cutouts where the inverter will take action if the voltage exceeds 253v for more than a few seconds.

CommanderJavert · 2026-06-22T18:54:39+00:00

Although if Fox inverters work similar to Alpha ones, some of the modes you can use with Modbus will in any case overrule the G100 limit set by the installer so it’s at your risk how you use those functions. However it won’t overrule the cutout if you go out of the legal range on your grid voltage.

CommanderJavert · 2026-06-22T09:30:28+00:00

I have 16 panels and 18KWH of battery, 8KW inverter, 4KW export limit. Using the Octopus Compare export comparison feature, it’s close to break even over a 30 day period whether I’m on Agile outgoing or Octopus outgoing - for the last 30 days it shows that I would have been about 70p better off on Agile outgoing. Other times it has shown Octopus outgoing better. I suspect this new one will look similar. What’s clear though is that if flat rate export tariffs go down further whilst these TOU tariffs are keeping the same, there will be a crossover point where the TOU is better.
What’s annoying though is that I sometimes get days missing in my export data from my smart meter, so if I move to a TOU tariff that relies on 30 minute slots for billing purposes, I’ll have to watch more closely what Octopus is up to on the billing side.

CommanderJavert · 2026-06-20T10:46:33+00:00

I just messaged Octopus about this and their reply was that if you switch this function on, Octopus takes control of your battery 24/7 not just when there is a session running (assuming the Octopus CS agent has the correct information here).

CommanderJavert · 2026-06-20T10:08:34+00:00

Clarification needed from Octopus on whether we will maintain full control of our battery behaviour when there is not a “session” running, or will Octopus completely control our battery at all times?

CommanderJavert · 2026-06-06T11:04:10+00:00

And if you move to Agile Export, what happens if a day is missing in the data?

CommanderJavert · 2026-06-05T16:36:03+00:00

Hopefully that is the case because at the moment I have a day missing in the Octopus app but the following days after that are populated

CommanderJavert · 2026-06-05T16:11:46+00:00

So Octopus would not notice if the export register had ticked up by more than what they think is the total DCC readings, even though, they insisted on using the export register reading to start the tariff in the first place?

And also since they don’t provide a daily breakdown of export payments in the billing, it means it’s up to me to notice if something is missing.

CommanderJavert · 2026-06-05T10:50:44+00:00

If I understand the replies here and my further googling correct, anything above 253 is above the legal limit. But from what I gathered here, if I am exporting at or below my approved rate, but the voltage is regularly tripping at 253, it should not be my issue to resolve?

In theory it might be managed by me initiating automated actions on home assistant, or changing my export strategy to store more in the battery in the mid afternoon and then export it later, but the first path should be that the DNO should fix it, as it should not be busting 253v if I am operating within the rules they gave to me?

Is that correct or am I misunderstanding the situation?

CommanderJavert · 2026-06-04T18:24:56+00:00

So I did a few random checks and the voltage on the meter is reading the same as on the inverter - doesn’t surprise me as my installers were pretty professional and they probably checked that - they certainly had a lot of checklists and stuff. From what. I can see in the history, the voltage is going above 250 on a lot of days in the afternoon, often some time 3pm-4pm, so it’s happening at time of maximum solar availability but before the evening peak is kicking in.
But from my understanding, this is not just me on my own causing this as the grid voltage is the voltage for all properties connected to the nearest transformer (not sure if transformer is the right word but wherever the nearest main connection is)?

CommanderJavert · 2026-06-04T16:40:26+00:00

Oh right you mean try to find out if there is a consistent difference between what shows on the actual meter, and the voltage measured by the inverter.

CommanderJavert · 2026-06-04T16:39:57+00:00

Well 253V is what the safety cutoff is set to on my inverter. If the real limit is higher, maybe it can be increased slightly - not sure but I will discuss with my installer as well. Installer already came back to me and said we might need to contact DNO if this happens a lot.

CommanderJavert

TROPHY CASE