Saving Sessions / Demand reduction thread

Ron-ski said:
My inverter tells me (but is about 5% out), but I also have HA setup to get the readings direct from the smart meter via a Glow IHD, that's the most accurate, and what were billed by.
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Guess I'll just have to wait.
All I did was no TV. And turned the dehumidifier off. Bit much what I could do except turning tiny things off like router and smart speakers, freezer that sort of thing.
 
I allowed my batteries to drop to 85% pre session which looking back was too low.
I had to disable export at 18:10 and just go to self use. Which meant I had some left, I just couldn't time it better.

Next time, 100% battery charge without fail ;)

10 days or so ago I decided to switch to grid use between 5-7pm since almost every day I was out of battery by late evening.
As such I calcuated my average from 5-6:30pm is actually 1.45kwh for the 10 days upto today excluding the last saving session. Thats adding a nice almost £6 to my amount today.

Should be in for about £25 total I think.
 
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On another note, I think I'm going to stop force discharging in the peak window now as it was quite alarming how bad the losses are going by last nights discharging.

I have 12.25kW of batteries and from min SOC to full charge they take about 10.6kWh using about 11.2kWh from the grid (5% loss). I force discharged from 92% to 10% last night and only got 6.9kWh out (over 25% loss!). I imagine its due to emptying them at the full 5kW but its enough to make it pointless, as even on the flux peak rate I'm barely making 4 pence a unit in reality and cycling the batteries a lot more.
 
reef said:
On another note, I think I'm going to stop force discharging in the peak window now as it was quite alarming how bad the losses are going by last nights discharging.

I have 12.25kW of batteries and from min SOC to full charge they take about 10.6kWh using about 11.2kWh from the grid (5% loss). I force discharged from 92% to 10% last night and only got 6.9kWh out (over 25% loss!). I imagine its due to emptying them at the full 5kW but its enough to make it pointless, as even on the flux peak rate I'm barely making 4 pence a unit in reality and cycling the batteries a lot more.
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Yep, I've stopped force discharging, especially now we have saving sessions going on, maybe miss out on a little bit of extra income (but not a huge amount once losses and the need to charge the battery more overnight are taken into account) but that will probably be counteracted by having a lower average export during the times when saving sessions are likely to occur, so therefore earning extra in the session.
 
reef said:
On another note, I think I'm going to stop force discharging in the peak window now as it was quite alarming how bad the losses are going by last nights discharging.

I have 12.25kW of batteries and from min SOC to full charge they take about 10.6kWh using about 11.2kWh from the grid (5% loss). I force discharged from 92% to 10% last night and only got 6.9kWh out (over 25% loss!). I imagine its due to emptying them at the full 5kW but its enough to make it pointless, as even on the flux peak rate I'm barely making 4 pence a unit in reality and cycling the batteries a lot more.
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What brand of batteries?

Only thing I will say, and you can track back my comments on this over time. With my Solax batteries the SOC is a number thats seemingly just made up.
The only time I can get a true idea of charge/discharge kWh is to go from 10-100 or 100-10. (%SOC)
Any other SOC% just cannot be trusted.

Also to add location / type.

LifePo4 needs 23c to be at 100% capacity it seems from reading around. My batteries were lab tested at 25c.
Solax haven't engaged in regards do they need to start at 25c, lol not fit for purpose in the UK then or is it fine to end at 25c. In theory if they are warming as they charge then the end temp should be key.

Mine show about 5.6% efficiency loss on charge. I think its less on discharge.
If I plot battery temp against charge/discharge when charging the temp goes up quickly, I think due to higher voltages. When discharging its less marked, but its far more rare that I discharge at a high rate for a sustained period.
 
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I agree SOC cant be trusted, I usually add/subtract kwh when a full charge is performed.

Example
1700945711-758998-image.png
 
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Mercenary Keyboard Warrior said:
What brand of batteries?

Only thing I will say, and you can track back my comments on this over time. With my Solax batteries the SOC is a number thats seemingly just made up.
The only time I can get a true idea of charge/discharge kWh is to go from 10-100 or 100-10. (%SOC)
Any other SOC% just cannot be trusted.

Also to add location / type.

LifePo4 needs 23c to be at 100% capacity it seems from reading around. My batteries were lab tested at 25c.
Solax haven't engaged in regards do they need to start at 25c, lol not fit for purpose in the UK then or is it fine to end at 25c. In theory if they are warming as they charge then the end temp should be key.

Mine show about 5.6% efficiency loss on charge. I think its less on discharge.
If I plot battery temp against charge/discharge when charging the temp goes up quickly, I think due to higher voltages. When discharging its less marked, but its far more rare that I discharge at a high rate for a sustained period.
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They're Fox HV25 batteries. The temperature makes a massive difference. In summer when they're 25-35C I get the full capacity. Now it's cold (15C or so even with insulation as the loft is under 5C) it's much lower.
 
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reef said:
They're Fox HV25 batteries. The temperature makes a massive difference. In summer when they're 25-35C I get the full capacity. Now it's cold (15C or so even with insulation as the loft is under 5C) it's much lower.
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Is that the Mira HV25 or an earlier version of the Fox HV2600?
I see a very high usable there (assuming the Mira version) of 11.9kWh on 12.28kWh nominal.
Your way short of capacity in that case very much like my issues.

Edit. An annoyance of mine is that yours as well as mine in specs talk about impact on charging from temps, not impact on capacity.
When in reality both are real and a consideration.
 
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They've always been available alongside the HV2600s so I have no idea on the differences. It used to be cycles but now the HV25s are also 6000 to 80% SOH. They're sneaky with the specs though as the 97% is the true usable and you then get 90% of that amount draining to min SOC. So 90% of 97% of the capacity. Hence the 10.6kWh from the 12.25kWh total.
 
Mine also seems to "lose" quite a bit when force discharging, especially at the higher rates. Given my export reading issues I'm not going to force discharge for the time being, so I'll see how things go, and if as you say, the saving sessions are always at peak time, then that may be of greater benefit.

I've spoken to Octopus again today, I do now have import readings on the app, but bizarrely I don't think they could see them. The guy said the meters do store six months worth of data, so all is not lost. I'll give until Monday and see what happens over the weekend.
 
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