Wanting to Pick the brains of you Octopus Guru's

[Kot]

So finally the install day is arriving fast. 10kWp split equally on South & West roofs and a 10kw battery, and an immersion diverter.
I want to use solar to fill up the battery and power the immersion heater try to use as much as I can and export anything left over.
I use 9250kwh/annum.
I dont have an EV.

I am currently on Flexible Octopus October 2022 v1 and now wondering which is my best Octopus option after install, during the start of summer lol
Outgoing fixed or outgoing agile? Then agile/flux/etc etc? for import

 

[johnb2713]

You have to be careful with Agile, as it's suggests, it jumps around all over the place price wise and you can end up buying some very expensive electricity if you're not on the ball. I was on GO, I'm now on Intelligent and run my system so the worst case scenario is my house is run 7.5p kWh or less. I don't use any peak rate at 40p kWh. I think GO is currently 9.5p kWh and whilst you should have an EV to go on it, they don't check, anyway you've got one ordered . GO doesn't pay much for export 4.2p but if you don't do much it doesn't matter.
You say you have an energy diverter, I have MyEnergi EDDI, it works well and you can gain more energy storage by turning the immersion heater thermostat up. I run mine at 85 deg C and have fitted a mixing valve on the outlet to drop the temp to 60 deg C to the house.

 

[novelsmike]

I don’t know what is best yet myself. I started with Octopus GO. But I was interested in getting at least something for exporting to the grid (I have exported 400 KwH so far since February). To do that you have to go to Agile. Agile is more expensive than GO for early hours usage (I have two EVs), but the other hour rates are lower than GO. It would take a mathematical genius (which I’m not) to work out what is best - it would depend on lots of variables. So I have just received my MCS certificate and DNO letter from my installer (needed to export to the grid) and so now I can apply for Outgoing Octopus.

 

[Andy1733]

I'm on Go, though I'm lazy and can't be bothered to shop around for the cheapest.

I have a 4kwh system with 10kwh battery's.
October - march I set the battery's to charge from the grid (1230am-4am).. those run my house and usually last to around 6pm (no solar generated). Upto midnight with some solar through the day.

 

[bladerunnerpv]

October - march I set the battery's to charge from the grid (1230am-4am).. those run my house and usually last to around 6pm (no solar generated)

Hi Andy1733, my initial reaction was surprise that 10kWh of battery was enough to run to 6pm in winter, out of interest what was your electricity usage per annum pre-solar install - just trying to compare to my situation where I use about 4000-4200 kWh p.a., and have you changed your usage much post-install?

 

[Andy1733]

Hi Andy1733, my initial reaction was surprise that 10kWh of battery was enough to run to 6pm in winter, out of interest what was your electricity usage per annum pre-solar install - just trying to compare to my situation where I use about 4000-4200 kWh p.a., and have you changed your usage much post-install?

About 6200 p.a.
my main alterations since solar is my koi pond. UV, heater, air pumps, water pump. All were running 24/7. At around 800 watts per hour. By buying a modern vari pump. Removing 1 air pump and only running the UV 12 hours during the day I've reduced it to about 450w.

 

[Andy1733]

Btw The 6200 was before solar. I switched to octopus in November last year and as of yesterday I have used 2156kwh. Which is 8 days short of 6 month. Obv summer should be very low.
From the 10kw battery's i prob drag 8kwh before they shut down.

I estimated solar/batterys would substitute about half my usage. Add this to the reduction in my base line I would have thought 3000kwh would be what I'm buying instead of the 6200 pre solar. Another factor is most of the 2156kwh so far are at the lower price of 12p (just reduced to 9.5p). My april bill was £56 Inc standing charge and we purchased 278kwh

 

[Andy1733]

Btw The 6200 was before solar. I switched to octopus in November last year and as of yesterday I have used 2156kwh. Which is 8 days short of 6 month. Obv summer should be very low.
From the 10kw battery's i prob drag 8kwh before they shut down.

I estimated solar would substitute about half my usage. Add this to the reduction in my base line I would have thought 3500kwh would be what I'm buying instead of the 6200 pre solar. Another factor is most of the 2156kwh so far are at the lower price of 12p (just reduced to 9.5p). My april bill was £56 Inc standing charge and we purchased 278kwh

Just checkedy April bill. It was actuall £58.2p. and from the 278kwh only 23.1kwh was at the higher tariff price.

 

[johnb2713]

I don’t know what is best yet myself. I started with Octopus GO. But I was interested in getting at least something for exporting to the grid (I have exported 400 KwH so far since February). To do that you have to go to Agile. Agile is more expensive than GO for early hours usage (I have two EVs), but the other hour rates are lower than GO. It would take a mathematical genius (which I’m not) to work out what is best - it would depend on lots of variables. So I have just received my MCS certificate and DNO letter from my installer (needed to export to the grid) and so now I can apply for Outgoing Octopus.

You can get payment for export on GO, been there, done that.

 

[Chrisbee]

Just out of interest, do you have to use Octopus for your export payments, if you're on one of these import tarrifs? Or can export be with a different company?

 

[novelsmike]

Export can be with another company

 

[Mr Aargh]

You need Flux. 24p export. Your water will often be heated by 4pm when the higher export rate starts of 37p. Use a gas kettle. So no need to use any leccy between 4 and 7. Tell them you've got a battery. You are hardly going to use any electric so you might as well get a lot for what you export.

Bt the way your install needs to be on two strings because it is on two roof aspects/elevations.

 

[johnb2713]

You need Flux. 24p export. Your water will often be heated by 4pm when the higher export rate starts of 37p. Use a gas kettle. So no need to use any leccy between 4 and 7. Tell them you've got a battery. You are hardly going to use any electric so you might as well get a lot for what you export.

Bt the way your install needs to be on two strings because it is on two roof aspects/elevations.

IMHO It's way better to plan to use all what you generate and export nothing, I consider I've failed if I export.
Last month I exported 7 kWh, imported 700 kWh off peak, 5 kWh Peak and exported 4 kWh all on Octopus Intelligent - Off peak at 7.5p, peak at 40p and export at 4.1p.

 

[Mr Aargh]

IMHO It's way better to plan to use all what you generate and export nothing, I consider I've failed if I export.
Last month I exported 7 kWh, imported 700 kWh off peak, 5 kWh Peak and exported 4 kWh all on Octopus Intelligent - Off peak at 7.5p, peak at 40p and export at 4.1p.

Shouldn't the aim be not importing?

 

[johnb2713]

Shouldn't the aim be not importing?

Not really, if I wasn't importing I would have massively oversized my solar PV. By not exporting and more importantly not importing at peak rate I feel the size of my system is pretty much optimal. I ran the figures today on a spreadsheet and were already £800 better off with the solar than we would have been without it and that includes the loan payments that we took out to have it installed.

 

[Mr Aargh]

Oversized pv is a bad thing because..?

 

[Andy1733]

Oversized pv is a bad thing because..?

Probably cost over performance/usage/needs...

 

[johnb2713]

Oversized pv is a bad thing because..?

The cost of the equipment
The real estate needed to site the array
The negative green aspects of such an array (manufacture, space, logistics)
What to do with the huge excess during optimum days

Apart from that nothing

My system in December generated 120.5 kWh, I use around 14,000 kWh per annum. The system I have cost £12,000. In order not to import from the grid I would need my system to be 10 times bigger, with a price tag of £120,000. It really isn't worth it and I feel there is a sweet spot between system investment and performance. I believe I have found that sweet spot which coincides with zero import of peak rate electricity and buying any additional energy I need off peak at 7.5p kWh. That said, my little system generated 5.1 MWh during the last 12 months so it's generated about a third of what I use.

 

[binky]

Oversized pv is a bad thing because..?

You need to find the sweet spot between investment and useage. Due to our latitude, we only get good irradiance levels for about 3/4 of the year, and then energy use is far less in summer, so you don't need a massive array to meet self use. Don't get me wrong, if your roof has space for say 20 panels rather than 14 as a single array, then the cost is worth it by the time you've paid for the scaffolding etc, the extra panels are not that significant a cost. If you start putting panels on extra roof orientations, a couple here, a pair there, then it's very debatable if it's worth the extra cost.

 

[Kot]

You need Flux. 24p export. Your water will often be heated by 4pm when the higher export rate starts of 37p. Use a gas kettle. So no need to use any leccy between 4 and 7. Tell them you've got a battery. You are hardly going to use any electric so you might as well get a lot for what you export.

Bt the way your install needs to be on two strings because it is on two roof aspects/elevations.

So thanks all for your inputs, interesting reads and it just shows there is not just 1 tariff that suits all.
In my case with no ev and a 10kwh battery.
I have sided with Mr Aargh (yes its on 2 strings) it's a no brainer for me in the summer. I can see the battery will be fully charged and the hot water up to temperature during the day. The late afternoon sun will feed the house demand from the west roof and extra will be exported at a competitive rate for my post code, 36.58p / kWh between 1600-1900hrs. Even during 0500-1600 its export rate is 22.98p. The import price is the same as what I am on now (flexible rate) between 0500-1600 so just need to shift my peak usage.
Then come Oct to April switch to Go/Agile! but who knows maybe Flux will also change rates during the winter?