Octopus - Which tariff now I have working smart meter, solar and battery?

lippofatty

Hi, This probably has no simple answer but I cant decide which tariff to go for with Octopus and am looking for some advice, they have given me options but I don't really know which one would best suit my setup and provide the best return. I have 6.75kW solar array and a Tesla Powerwall II battery (without backup) that were installed approx. 9 years ago when my house was built. Due to a timing/order mistake on my part at the time I only got the reduced FIT rate (like the commercial rate). Additionally it has taken years to finally get a smart meter working in my rural location (NE Scotland) but a new 4G version was installed recently and works so I can now choose a smart tariff. My FIT agreement is currently via a different provider and I also need to decide if its better to move the FIT to Octopus and choose one of their Export tariffs and move to the Flux Tariff (Intelligent Flux tariff not available at time of writing). I don't have an electric vehicle and unlikely to get one anytime soon. My current FIT setup measures generation but not export (just paid half of generation figure, but at the reduced rate). I tend to try my hardest not export electric (due to the poor rate) and have a myEnergi Eddi that sends any extra leccy to 2 immersion heaters I have installed in a 2000L buffer tank (part of a pellet boiler system). These heaters don't really make much of a dent in that size of tank but it means I only export when both the battery is full and the tank wont accept anymore heat (I usually only export larger amounts on sunny summer days) Should I leave the FIT where it is? I doubt I will get the better export rate by moving it anyway. The Flux tariff looks interesting and I had a look at the Virtual Power plant feature in the Tesla app which might be of benefit. I definitely like the idea of charging the battery overnight during the winter months as I don't get enough sun then to fully charge the battery everyday. The panels are also South East facing rather than full South. I don't really want the extra work of the Agile system, from what I understand I'd need extra software like PreBat. Prefer to keep it simple. Just wondering if anyone had a similar dilemma and what choices they made and whether they think it was the right one. Thanks

QrizB

Welcome to the forum!

Let's break this down.

Should I leave the FIT where it is?

The FIT generation tariff (the payment for every kWh you generate) may as well stay where it is. The export tariff (payment for every kWh you export, currently deemed to be half your generation) is another matter.

I tend to try my hardest not export electric (due to the poor rate) and have a myEnergi Eddi that sends any extra leccy to 2 immersion heaters I have installed in a 2000L buffer tank (part of a pellet boiler system).

Your FIT is probably paying 7.64p/kWh? That's not terrible, particularly since (for the moment) you don't have to export anything at all in order but still get paid the deemed amount.

Octopus's current Outgoing Fixed export tariff pays 12p/kWh, but you'll only get paid for electricity you genuinely export. No deemed quantities there.

I have 6.75kW solar array and a Tesla Powerwall II battery

I don't know how much electricity your household uses in a year (ignoring solar diversion) but it's fairly likely that you'd be better off with a tariff that has a cheap off-peak period when you can charge the PWII, allowing you to export your solar at 12p/kWh.

It's unfortunate that Intelligent Flux isn't taking new sign-ups. The Tesla VPP doesn't work well with regular Flux as you end up paying more for import than you earn for export.

I don't have an electric vehicle and unlikely to get one anytime soon.

And that rules out the next most common option; I'm on Intelligent Go which means I can charge my battery / heat my HW tank for 8p/kWh while exporting solar electricity in the daytime for 12p/kWh.

Prefer to keep it simple.

Your best option, then, might be boring old Economy 7, at least for now. Seven hours every night at ~13-14p/kWh, during which you can charge your PWII. Leave your export tariff with your FIT (since there's unlikely any gain in moving it) and wait for IOG to open up to new customers again.

lippofatty

Hi, Thanks for your quick and detailed reply, very helpful. I suspected FIT agreement might be better left alone so thanks for confirming that, yes we get around the 7.64 rate. I would say the household is fairly heavy use, I'll have to look at past records. Not sure if I can get the Economy 7 rate but I will investigate that.

Can I ask if I leave the FIT where it is and went with Flux for now am I right in thinking can I still top up the battery overnight at the 2-5am period, without using the VPP feature? or does it rely on this?

I presume the Flux Export rates are not on top of the FIT export payments? These are the current Flux rates Octopus are quoting for my postcode:

Day rate
Import 25.59p / kWh Export 9.98p / kWh

Flux rate (02:00 - 05:00)
Import 15.36p / kWh Export 4.73p / kWh

Peak rate (16:00 - 19:00)
Import 35.83p / kWh Export 28.73p / kWh

Intelligent Go looks like a good option too, maybe I have to get over my electric car aversion.

QrizB

Can I ask if I leave the FIT where it is and went with Flux for now am I right in thinking can I still top up the battery overnight at the 2-5am period, without using the VPP feature? or does it rely on this?

Flux is an import and export tariff so you'd need to give up the FIT export payments. You can't get both.

If you did that, yes you could charge your PWII overnight on the 3 cheap hours. You'd need to confirm that you can do everything you need to do in those three hours (I don't know the max recommended charge rate for a PWII, for example).

Octopus say you should only join the VPP if you're on Intelligent Flux, and there's a thread over on Green & Ethical that showeds what goes wrong if you combine it with regular Flux. I'll add a link once I've found it!

Edit: here's the link.

MWT

https://forums.moneysavingexpert.com/discussion/comment/82110809#Comment_82110809

(I don't know the max recommended charge rate for a PWII, for example).

In TBC mode it will take 5kW per Powerwall or in Self-Powered mode it is around 3.3kW.

In Backup mode it will take around 3.6kW.