Solaredge on Octopus IOF

Qyburn

Hi,

Now that Octopus is dropping their fixed export rate it's time to look again at IOF sooner rather than later. When the Solaredge integration was first added there were report of serious problems, I'm hoping these are now fixed.

Can any members currently on IOF with Solaredge gear comment on how they're finding it?

Netexporter

Is there a Solaredge forum, perhaps attached to their website? Or a search on Youtube might turn something up.

Screwdriva

Lots of success stories for existing SolarEdge customers on IOF.

Sadly, the battery's cold weather performance has been poor, which has diminished charge/ discharge rates, which then leads to the odd glitch or three.

Qyburn

Cheers, there were a few problems reported on the Solaredge Facebook group when the integration was first launched. Just now it's being reported that in between Octopus controlled "charge from grid" or "discharge to grid" sessions the battery doesn'doesn't discharge to serve house loads. That's just one report, although nobody else has popped up to say theirs is any different.

I'll need to find out whether that's expected behaviour, in which case I won't be signing up. I anticipate some difficulties getting Octopus to even understand the question, let alone answer it.

So as of now I have only two actual first hand reports, one reporting that behaviour. The other said he switched off the tariff because he wanted to take back direct control, although not saying exactly what he disliked.

Shame about cold performance, not something that was ever reported a couple of years ago when Solaredge was flavour of the month. But it's something that has to be lived with, I don't see it specially impacting IOF.

NedS

https://forums.moneysavingexpert.com/discussion/comment/81894828#Comment_81894828

Why would it discharge to the house load? It's the same price to import from the grid as it is to export, so it's actually more efficient / cheaper to pull from the grid for your house load as you are not incurring conversion losses.

Last summer, expected behaviour (albeit with a tesla) was that Octopus would discharge the battery down to the 20% reserve during the 4-7pm evening peak. The battery would sit at 20% overnight, with house load drawn from grid. Solar would power the house load during the morning during which time the battery would fill with any excess solar. Octopus would then normally grid charge early afternoon if not already full from excess solar ready for the 4-7pm peak discharge again.

Very occasionally Octopus would charge to 50% overnight if there was an abundance of wind, but this only happened on a handful of occasions.

Sounds like the first person doesn't understand the tariff and the second person doesn't want to give up control (I see that a lot of the tesla Facebook groups).

Qyburn

https://forums.moneysavingexpert.com/discussion/comment/81895511#Comment_81895511

Why would it discharge to the house load? It's the same price to import from the grid as it is to export, so it's actually more efficient / cheaper to pull from the grid for your house load as you are not incurring conversion losses.

Wouldn’t you want to draw from battery, rather than grid, during peak hours?

Qyburn

Sounds like the first person doesn't understand the tariff

That's probably me as well. The price being the same for import means a lot of previous assumptions and principles are out of the window.

The guy who wanted control, I think he might be the one who in the early days kept seeing his battery stuck at 100% with neither Octopus nor Solaredge able to control it. That must have been an early integration glitch. Facebook is really bad at trying to find older posts so that's just going by my memory.

NedS

https://forums.moneysavingexpert.com/discussion/comment/81895566#Comment_81895566

Last year, the rates for my area were about 23p and 30p per kWh for the evening peak.

During the evening peak, Octopus are discharging the battery. As you cannot physically import and export from the grid at the same time, the battery will be meeting the house load and exporting to the grid. If the battery is large enough to last the whole 3h period, great. If not, at some point it may run out (or down to it's reserves) and you'll end up importing from the grid for the remainder. But as the price for import and export is the same, it makes no difference if you export some power at 30p and then end up reimporting some back at 30p because the battery ran out - it's exactly the same as just not exporting so much to start with and using it from battery to power the house rather than exporting it.

Lets look at a trivial example - say you have a 10kW battery. Octopus will likely set a 20% reserve, so they are going to try to discharge 8kW during the peak. Lets say the house needs 2kW during this period, so the battery can supply 2kW to the house and export the remaining 6kW at 6 x 30p = £1.80

Now imagine the battery is empty half way through the period. At this point the house as used 1kW and 7kW have been exported giving 7 x 30p = £2.10 of export, but you now need to import 1kW during the remaining period to power the house at a peak rate of 30p, so again the overall net profit is £2.10 - 30p = £1.80

In summer, you will normally also still have some solar 4-7pm which is great and extends the life of the battery adding to the total amount of power available for export at peak rate (30p).

As it's a net use tariff (same price for both import and export), the ONLY thing you really need to do is try to ensure you export as much as possible, and the only way you can affect this is by trying to minimise your usage (as you cannot control your generation). In particular, try to minimise your usage at peak rate so more is exported. The more you export (and the less you use), the more you make. Every kWh you don't use, you will be paid 23p or 30p for exporting. Last summer, we were generating 2.5-3 times our usage, and achieved an average of 26p per kWh for our export.

Qyburn

https://forums.moneysavingexpert.com/discussion/comment/81895865#Comment_81895865

During the evening peak, Octopus are discharging the battery.

Have you ever seen them discharging to grid outside the peak hours?

NedS

https://forums.moneysavingexpert.com/discussion/comment/81896261#Comment_81896261

Maybe once or twice in summer, around lunchtime, but this is not common in my experience. I presume the logic was that they wanted to create space in the battery to allow grid charging in the early afternoon to soak up some of the solar excess on a very sunny day - the types of days where Agile prices go negative due to excess supply. But it doesn't really matter from a monetary perspective what it does (other than considering conversion losses) as the import and export prices are the same.

What you have to remember is that Octopus are paying you handsomely for being allowed to take control of your battery for them to use to support the grid. They may or may not use it in a way that additionally benefits you, above and beyond the very generous rate they are already paying you for it's use.

A very simplistic view would be that you are going to receive around 25p per kWh for any excess electricity you generate during summer (I averaged around 26p last year). You know roughly what you consume. You know (or can predict) roughly what you will generate. You will receive around 25p per kWh on average for the excess, that is roughly what you're going to get paid. Then decide if that's sufficient additional revenue to be worth it for you versus the alternatives.

Using this simplistic model, I know I'm going to generate around £700 in excess export payments in the 6 months April - September. If I stayed on Cosy/SEG, I'd import next to nothing (running completely on solar/battery) and export excess at 12p/kWh giving closer to £330, so I'm making more than double, an additional £370 by using IOF. This additional revenue ensures our winter usage is covered and we are net zero costs for the year.

I really like IOF in summer as (a) it actually does a good job of managing my excess solar as it keeps the battery empty during the morning by exporting excess solar and only charges above my export limit which helps to prevent clipping, and (b) I don't have to worry about micro-managing the aforementioned clipping myself, I can leave it to do it's thing and be paid a very generous rate for the privilege.

I should add that I only have experience of IOF from last summer, and I understand behaviour in winter may be different.

Qyburn

I just signed up. Tariff is in effect from start of March. Today the battery under their control, I saw a series of parameters changing from aboabout 12:00 today. It's just reached 100% with excess solar being exported. My automation would have switched to "Discharge to minimise import" before it reached 100%, so there's space in the battery for when solar power exceeds inverter output. Not so much of an issue at this time of year.

Will be interesting to see how it behaves at 16:00.