Outgoing Octopus

[Stinsy]

Strange world this IOG and OO tariff combo! Completely changes the thinking…

Previously, in winter, I’ve worked hard to conserve every kWh to get my teeny battery as close to the start of the cheap period as possible, then to try to use as little peak-rate electric as possible. Now I relax, as soon as the battery runs out I plug the car in and get additional cheapslots. Even if it doesn’t seem sensible (eg I need 4hrs of charging) Octopus gifts me cheap electric when I need it, at peak times.

In summer, I’m used to working hard to consume what I generate, ‘cos otherwise it is wasted. Cranking the AC, suggesting to the Mrs that she washes the towels/bedding, cooking a batch for the freezer, anytime the sun shines. But now I get paid for exporting I’ll be conserving in summer to export as much as possible.

[Andy]

Andy, your idea of dispatching as much as possible between 16:00 and 19:00 just to be nice to Octopus will reduce your benefit as you will lose a fair bit in the charge and discharge transfer through the battery. Better to just let the excess solar export as its generated on fixed Outgoing at 15p, then import and use during the night time on 7.5p.

The problem I have is that I can't export at full rate as the voltage rises too much. I had to update my SolarEdge as part of the G99 application and I discovered that whereas the inverter used to limit to 253V before cutting out it seems that the settings now are well over 260V. I forget off hand the exact amount. I let it do its thing on the first day and was very concerned at the voltages reached. A few bits of kit died shortly after which may or may not have been a coincidence. Not wanting to tempt fate with anything else I have since limited my export to 250V. Looking back through my records this has been as low as 5.5kW in the peak of summer. I was thinking that exporting as much as possible throughout the day. This would be primarily from the AC side and any spare being buffered from the DC side to the battery. Since I have stored the solar in the battery already it would make sense to assist Octopus as much as possible to make the tariff worth it to them since altruism will only take them so far.

Yellow line on the top graph is the maximum I could export in order to try and maintain 250V in the house.

[Andy]

Strange world this IOG and OO tariff combo! Completely changes the thinking…

Previously, in winter, I’ve worked hard to conserve every kWh to get my teeny battery as close to the start of the cheap period as possible, then to try to use as little peak-rate electric as possible. Now I relax, as soon as the battery runs out I plug the car in and get additional cheapslots. Even if it doesn’t seem sensible (eg I need 4hrs of charging) Octopus gifts me cheap electric when I need it, at peak times.

In summer, I’m used to working hard to consume what I generate, ‘cos otherwise it is wasted. Cranking the AC, suggesting to the Mrs that she washes the towels/bedding, cooking a batch for the freezer, anytime the sun shines. But now I get paid for exporting I’ll be conserving in summer to export as much as possible.

It is indeed a huge paradigm shift. It leads to quite a few nuances. I thought it might be better to think of it as exporting every last drop of solar by powering the house with the battery charged during the night period. ie start the day with enough battery to get through the day and send the rest to the grid. However, when I worked out the cost per kW in the battery over its life time it comes to about 7p. So having charged at 7.5p and then costing 7p for using it, it is actually about breakeven. The saving of solar->battery->grid is actually only about 7-8p as you have used the battery which comes at a cycle cost.

However as I mentioned somewhere else there is the aging of the battery to consider. My SOH is down to 98% and probably 97% after a year with only about 210 cycles (177 today). It might be better to just pay back the battery now by using it while it can still hold a lot and then get a newer one rather than trying to eke its life span 16 years. I'll be putting aside some money to replace the batteries in the future. Maybe DIY and much bigger, we will see what is around.

Also, Bimble have 35 solar panels for £3300 giving 14.3kW. Maybe I should just add more panels Again I've been told a flat no! I might be able to hide a couple of batteries but not the solar

Simple maths of a normal tariff of 28kW vs the octopus I'm saving £6400 per year if I get more batteries. From the start the whole installation will pay back in around 6 years flat. Actually longer since it's all on the mortgage but it's not too much extra. Octopus withdrawing the tariff or export is a concern. Withdrawing from the FIT is paid back with the savings with in about a year so that isn't too much of a risk.

[Stinsy]

I’m not sure it is helpful to measure battery life on that basis. Research on BEV batteries shows that calendar age and luck (if you get a bad cell you get a bad cell) have a bigger effect than number of cycles. Also batteries don’t last their 6k cycles then expire immediately, their capacity reduces gradually over time. They’re typically considered EoL when they get down to 60% of their original capacity. You can possibly expect 75-80% of your original capacity after 10 years and 3,000 cycles. I’ll be interested to find out if our Pylontechs will be still working and at what capacity after 20 years and 6000 cycles. However I ready believe that it’ll be time that gets ‘em rather than cycles. Therefore the onus is to use the battery as hard as you can and extract as much value out of it as possible while it lives. IMO cycling your battery less because you believe it’ll last longer that way is false logic.

I’ve long agonised over expanding my teeny battery. It fills faster than I can use the electric in summer and empties before the cheap period starts again in winter. However with the new IOG/OO combo my battery is fine. In summer I can let the export happen with abandon (might even “force export”) and in winter I can plug the car in as soon as the battery is exhausted for additional cheapslots. While this continues I have no need to expand my battery. (I’ve been saying for a while that this is a too-good-to-be-true situation that cannot possibly last forever).

Buying a battery solely on the basis that you can buy at 7.5p and sell at 15p probably doesn’t make financial sense. But using a battery you already have to do so is worthwhile IMO.

[Yuff]

The elephant in the room is v2h and v2g, if they come in most of us have 100 + kWh of storage on our drives etc.
Also we don’t know what tariffs octopus will continue to promote so probably best to make hay whilst the sun is shining.
If the options stayed as they are, then it would not be worth us getting extra storage etc, but if IOG was altered then I would need more batteries in the winter, add into the mix saving sessions being able to export etc I think I’ll be investing in more batteries on feb 1st when vat is removed.
The payback is not that long and I think I’ll be close to achieving zero cost over the year, which based on my DD estimate, of £866 per month, before I switched to heat pumps etc seems a pretty good return. That was at the inflated prices in oct 2022 at the height of the energy crisis.

[nowty]

Buying a battery solely on the basis that you can buy at 7.5p and sell at 15p probably doesn’t make financial sense. But using a battery you already have to do so is worthwhile IMO.

Agree, as I primarily have batteries to avoid the peak rate import at a 23p difference.

The 7.5p difference is not enough on its own and will likely not be around indefinitely.

The 200p+ difference on the saving sessions is also a very welcome bonus. I see the saving sessions in conjunction with free power hours may be a more sustainable thing.

[Stinsy]

The elephant in the room is v2h and v2g, if they come in most of us have 100 + kWh of storage on our drives etc.
Also we don’t know what tariffs octopus will continue to promote so probably best to make hay whilst the sun is shining.
If the options stayed as they are, then it would not be worth us getting extra storage etc, but if IOG was altered then I would need more batteries in the winter, add into the mix saving sessions being able to export etc I think I’ll be investing in more batteries on feb 1st when vat is removed.
The payback is not that long and I think I’ll be close to achieving zero cost over the year, which based on my DD estimate, of £866 per month, before I switched to heat pumps etc seems a pretty good return. That was at the inflated prices in oct 2022 at the height of the energy crisis.

£866 per month?

I’ve recently increased my DD from £100 to £150 a month! That is for 2x EVs and all heat as well as other electric in a 5-bed house!

[Andy]

.... in winter I can plug the car in as soon as the battery is exhausted for additional cheapslots.

I've been wondering about them. How often do you get them? They would be very useful to stretch through the day.

The 200p+ difference on the saving sessions is also a very welcome bonus. I see the saving sessions in conjunction with free power hours may be a more sustainable thing.

If I have zero grid usage all the time I presume I can't actually make any savings at that point?

[Yuff]

The elephant in the room is v2h and v2g, if they come in most of us have 100 + kWh of storage on our drives etc.
Also we don’t know what tariffs octopus will continue to promote so probably best to make hay whilst the sun is shining.
If the options stayed as they are, then it would not be worth us getting extra storage etc, but if IOG was altered then I would need more batteries in the winter, add into the mix saving sessions being able to export etc I think I’ll be investing in more batteries on feb 1st when vat is removed.
The payback is not that long and I think I’ll be close to achieving zero cost over the year, which based on my DD estimate, of £866 per month, before I switched to heat pumps etc seems a pretty good return. That was at the inflated prices in oct 2022 at the height of the energy crisis.

£866 per month?

I’ve recently increased my DD from £100 to £150 a month! That is for 2x EVs and all heat as well as other electric in a 5-bed house!

That was pre ASHPs, batteries and solar installation plus IOG.
Taking into account saving sessions, OO etc I think I’ll be neutral this year, 3 EVs, heating a 6 bed house. Ripple 3 will probably put me into credit 6000 kWh purchased. If I can get 2 new batteries plus a 2nd inverter and the inverter replaced, where they supplied an old slower one, I should be making a decent profit…….

[Fintray]

.... in winter I can plug the car in as soon as the battery is exhausted for additional cheapslots.

I've been wondering about them. How often do you get them? They would be very useful to stretch through the day.

The 200p+ difference on the saving sessions is also a very welcome bonus. I see the saving sessions in conjunction with free power hours may be a more sustainable thing.

If I have zero grid usage all the time I presume I can't actually make any savings at that point?

I'm much the same at the saving session times of day but you can always export and get paid for that at the savings rate.