Octopus Flux Battery Charging strategy

[wc1966]

I recently installed 8kw of solar on a south facing roof with a 5kw Hybrid Givenergy inverter and a 9.5kw/h Givenergy battery. An oversized system!!

I'm on the flux tariff and as most flux users one of the core strategies is to dump the battery as much as possible between 4 and 7pm. I've I have set on about 2kw discharge so after 3 hours i tend to retain about 25% to get me through the evening.

The question should I try and charge the solar battery during the day or instead just fully charge 2-5am then discharge and good for max export. On poor days like yesterday things come unstuck and at 4pm I only had 60% on the battery so export is limited.

I other consideration is should I have a different strategy in really decent spells of weather. Take the example below when I have clear skies.

Am I better delaying my charge till the sun gets high, then using the excess >3.6kw to charge the battery or have I understood that incorrectly? Any advice welcome, I'm on a rapid learning curve with this stuff!!

 

[Scruffy D]

Personally I only charge the batteries overnight in the winter months, from April to October the sun runs the house and charges the batteries and heats the hot water. I'm not familiar with the Flux tariff, but I assume you get a very good return for exporting that makes it worth while?

An "oversized system " won't feel so over sized in the winter when your panels produce about a third or less of their capacity.

 

[wc1966]

Personally I only charge the batteries overnight in the winter months, from April to October the sun runs the house and charges the batteries and heats the hot water. I'm not familiar with the Flux tariff, but I assume you get a very good return for exporting that makes it worth while?

An "oversized system " won't feel so over sized in the winter when your panels produce about a third or less of their capacity.

I'm adopting the strategy of putting the washing machine and dishwasher on 2-5am (18p/unit) and keeping 20% on the battery, if the day is looking poor (like today) I up it for 50% to ensure I have 100% at 4pm for maximum peak return in the 4-7pm period.

Surely its in winter oversizing really comes into its own as there is no solar clipping. I hoping I can average 4kw in December and won't be far off revenue neutral if I can still export a few kw in the peak period

 

[Mr Aargh]

December you won't be exporting much I am afraid. It may be though that if you have battery dishwasher car immersion heater and washing machine happening at night then the Go tariff is better for winter. You could find that your daytime highest electricity use would then be the oven - in which case might I recommend a ninja Foodi? Only 1.4 kw device - does what often an oven can.

 

[Kot]

with Flux I charge between 2am and 5am, use as much as I can, for self needs and then usually exporting from 10am in the summer.
I do not dump between 4pm and 7pm as usually still exporting anyway.
Not a favourite of leaving washing machine or tumbler plugged in after the numerous fires reported with well known brands etc especially 2am!!! shock horror.

 

[offgridAndy]

from my experience, about 20 yrs of living off grid with PV and a WT, if you get 10% of your rated PV output in the 3 winter months you be doing well. I.e. if you have an 8Kw array you may see 800 watts produced in a day in December. I'd suggest you make any plans for winter useage based on that scale of production.

 

[johnb2713]

Not a favourite of leaving washing machine or tumbler plugged in after the numerous fires reported with well known brands etc especially 2am!!! shock horror.

So do you sit and watch the tumble drier poised with a fire extinguisher in your hand? Never leave it unattended?
Heres a tip for you, ditch the tumble drier and buy a heat pump one, you'll save a fortune in energy use and theres no danger of fire.

 

[glenns]

So do you sit and watch the tumble drier poised with a fire extinguisher in your hand? Never leave it unattended?
Heres a tip for you, ditch the tumble drier and buy a heat pump one, you'll save a fortune in energy use and theres no danger of fire.

Picked up a Samsung heat pump dryer in December. (Got fed up seeing damp clothes on radiators)

Fantastic bit of kit!!...will do a full load on less than half a kW

 

[johnb2713]

Picked up a Samsung heat pump dryer in December. (Got fed up seeing damp clothes on radiators)

Fantastic bit of kit!!...will do a full load on less than half a kW

Yup, we bought a beko one, 9Kg load, absolutely superb, great for running on solar + batteries

 

[wc1966]

December you won't be exporting much I am afraid. It may be though that if you have battery dishwasher car immersion heater and washing machine happening at night then the Go tariff is better for winter. You could find that your daytime highest electricity use would then be the oven - in which case might I recommend a ninja Foodi? Only 1.4 kw device - does what often an oven can.

Yeap I’m expecting a switch from flux to the Go or Intelligent Tariff at some point. I reckon around the time the clocks go back.

Thanks for the Ninja tip !!

 

[johnb2713]

Yeap I’m expecting a switch from flux to the Go or Intelligent Tariff at some point. I reckon around the time the clocks go back.

Thanks for the Ninja tip !!

I have never seen the point of flux or agile over intelligent. Intelligent gives me 7.5p for 6 hours and 29.2p peak, the latest agile rates have just been msgd to me highest 32.7p, lowest 15.4p, export may be better, 12p the last time looked but I can get that from Scottish Power or EON, I just dont see how agile is an attractive proposition.

 

[wc1966]

I have never seen the point of flux or agile over intelligent. Intelligent gives me 7.5p for 6 hours and 29.2p peak, the latest agile rates have just been msgd to me highest 32.7p, lowest 15.4p, export may be better, 12p the last time looked but I can get that from Scottish Power or EON, I just dont see how agile is an attractive proposition.

Flux is paying 19p export and about half my export goes out at 31p, so about 25p average.

Go / Intelligent is about 4p export. A great tariff for EVs but for solar in summer ?

 

[johnb2713]

Flux is paying 19p export and about half my export goes out at 31p, so about 25p average.

Go / Intelligent is about 4p export. A great tariff for EVs but for solar in summer ?

I've just checked the flux rates and I still dont see it (I'm maybe being thick or not in the real world according to murdoch). The Flux rates are:
Import
29.6p
02:00 - 05:00 - 17.56p
16:00 - 19:00 - 40.97p
Export
18.26p
02:00 - 05:00 - 6.56p
16:00 - 19:00 - 29.97p

So, if I charge my 21 kWh of storage on Intelligent it costs me £1.57 and I use the energy myself. If I did the same on Flux it would cost me £3.68 but then I could sell it later £6.29, a profit of £2.61 but I then have to buy energy at 29.26p to power my house between the flux times would cost me £3.16 with a 600w background load. Sure the export rate on Intelligent is poor at 4.5p but I always aim to not export by adjusting my import overnight.
It seems a lot of faff for very little reward, especially when winter hits.

 

[wc1966]

I've just checked the flux rates and I still dont see it (I'm maybe being thick or not in the real world according to murdoch). The Flux rates are:
Import
29.6p
02:00 - 05:00 - 17.56p
16:00 - 19:00 - 40.97p
Export
18.26p
02:00 - 05:00 - 6.56p
16:00 - 19:00 - 29.97p

So, if I charge my 21 kWh of storage on Intelligent it costs me £1.57 and I use the energy myself. If I did the same on Flux it would cost me £3.68 but then I could sell it later £6.29, a profit of £2.61 but I then have to buy energy at 29.26p to power my house between the flux times would cost me £3.16 with a 600w background load. Sure the export rate on Intelligent is poor at 4.5p but I always aim to not export by adjusting my import overnight.
It seems a lot of faff for very little reward, especially when winter hits.

For me the comparison would be as follows in the summer months

10kw batt charged on Flux @ 18p/kWh =£1.80

Average generation per day 28 kWh

Daily home usage 7 KWh

Daily export 10kWh @ 19p kWh = £1.90
11kWh @ 31p kWh = £3.41

Daily Profit = £5.21-£1.80=£3.41


10kWh batt charged on Inteligent @ 7.5/kWh =£0.75

Average generation per day 28 kWh

Daily home usage 7 KWh

Daily export 21kWh @ 4.5p kWh = £0.98

Daily Profit = £0.98-£0.75=£0.23

When my generation slumps I think Intelligent might work better for me. Flux works well for me as I've quite a low user with high generation.

Reduce my system to 5kw and chuck in an EV the numbers start to change

 

[Kot]

I've just checked the flux rates and I still dont see it (I'm maybe being thick or not in the real world according to murdoch). The Flux rates are:
Import
29.6p
02:00 - 05:00 - 17.56p
16:00 - 19:00 - 40.97p
Export
18.26p
02:00 - 05:00 - 6.56p
16:00 - 19:00 - 29.97p

So, if I charge my 21 kWh of storage on Intelligent it costs me £1.57 and I use the energy myself. If I did the same on Flux it would cost me £3.68 but then I could sell it later £6.29, a profit of £2.61 but I then have to buy energy at 29.26p to power my house between the flux times would cost me £3.16 with a 600w background load. Sure the export rate on Intelligent is poor at 4.5p but I always aim to not export by adjusting my import overnight.
It seems a lot of faff for very little reward, especially when winter hits.

I have never seen the point of flux or agile over intelligent. Intelligent gives me 7.5p for 6 hours and 29.2p peak, the latest agile rates have just been msgd to me highest 32.7p, lowest 15.4p, export may be better, 12p the last time looked but I can get that from Scottish Power or EON, I just dont see how agile is an attractive proposition.

the point is---
Quote on Octopus website----To join Intelligent Octopus, you will need an Ohme charger, or have a Audi, BMW, Cupra, Ford (only Mach E), Jaguar, Jeep, Kia, Land Rover, Mini, Porsche, Renault, SEAT, Skoda, Tesla and Volkswagen car.

If you already have a charger, check out our other EV tariff, Octopus Go.

 

[Kot]

So do you sit and watch the tumble drier poised with a fire extinguisher in your hand? Never leave it unattended?
Heres a tip for you, ditch the tumble drier and buy a heat pump one, you'll save a fortune in energy use and theres no danger of fire.

LOL No -- but it's on when the sun is shinning, we are home, instead of lying asleep at night. My daughters friend nipped out to the shops to return to a kitchen fire that gutted the house.
It's just good practice to not use a tumble dryer when the whole house is asleep just to save a few pence!


https://www.southwales-fire.gov.uk/newsroom/news/tumble-dryer-dos-and-donts/
https://uk.news.yahoo.com/tumble-dr...Cij1emyPFlwvGlK5w7fFoUV6u1fQT8UYP8fKNM_9J4mix

 

[Geoff1946]

Commercial tumble dryers incorporate a fire suppression system. Domestic ones don't.
Blowing air from a near red hot element over flammable materials is obviously risky, so no, I wouldn't have one running whilst I slept, or went out.

 

[johnb2713]

Commercial tumble dryers incorporate a fire suppression system. Domestic ones don't.

Correct

Blowing air from a near red hot element over flammable materials is obviously risky, so no, I wouldn't have one running whilst I slept, or went out.

But with a heatpump tumble drier, non of that happens. Very similar to a domestic fridge or freezer in operation.

 

[johnb2713]

LOL No -- but it's on when the sun is shinning, we are home, instead of lying asleep at night. My daughters friend nipped out to the shops to return to a kitchen fire that gutted the house.

There are always horror stories, a infinitely small percentage of conventional tumble drier, poorly designed and probably not operated correctly cause the issues.

It's just good practice to not use a tumble dryer when the whole house is asleep just to save a few pence!

It's good practice not to use resistive heated tumble driers at all, heatpump ones are the way to go, they cost only a fraction more, save a fortune on running costs, why risk a fire at all just to save a few pence?
.

 

[wc1966]

the point is---
Quote on Octopus website----To join Intelligent Octopus, you will need an Ohme charger, or have a Audi, BMW, Cupra, Ford (only Mach E), Jaguar, Jeep, Kia, Land Rover, Mini, Porsche, Renault, SEAT, Skoda, Tesla and Volkswagen car.

If you already have a charger, check out our other EV tariff, Octopus Go.

I don't think they police it and I don't think they can tell whether you are using Go to charge an EV or home battery.