Soldato
- Joined
- 19 Oct 2010
- Posts
- 2,553
I'm gonna rooll the dice today then and use some grid from -4 to -1 before 17:00 and see what happens. I've got a historical baseline of zero units in the 17:00 to 18:00 window.
Solar panels and battery - any real world reccomendations?
- Thread starter GinG
- Start date
Man of Honour
Well for the past week I've used next to nothing in the afternoons thanks to good solar and storage - so will this affect me? Or is it worth shoving the batteries on charge for an hour or so before the session?
Soldato
Will be really interesting to see your "savings" in that case.
I calculated my usage is 1.6kwh average over last 10 working days. That will be zero today, so any other affecting number will come from -4 to -1 usage.
I will grab the data off octopus tomorrow and wait for the calcs to come in end of the week.
We dont really have enough data so you like john_smith would be a good base case.
Its -4 to -1 hours though (1-4pm) so don't charge after 4 its too late
Man of Honour
Will be really interesting to see your "savings" in that case.
I calculated my usage is 1.6kwh average over last 10 working days. That will be zero today, so any other affecting number will come from -4 to -1 usage.
I will grab the data off octopus tomorrow and wait for the calcs to come in end of the week.
We dont really have enough data so you like john_smith would be a good base case.
Its -4 to -1 hours though (1-4pm) so don't charge after 4 its too late
I'll set it to charge (unless they're full
) from that time and just take a hit - if it works out to cost me more than I save, I'll just cry in the corner. 
That said I seem to be doing okay from the saving sessions previously.
Soldato
- Joined
- 19 Oct 2010
- Posts
- 2,553
I'm not sure i'm going to be able to do anything. Nobody is home, my battery is at 100% and all of my PV now is going into the hot water. My car is with me. Damn.
Soldato
Soldato
Ok dug out the calc, per National Grid
"3. In-day adjustment (Domestic consumers only)
The in-day adjustment is calculated using the 6 Settlement Periods between Event Time- 4 Hours (E4) and Event Time- 1 Hours (E-1).
For example, if the DFS event happens at 18:00, the E-4 is 14:00 and E-1 is 17:00, the in-day adjustments would be calculated using Metered Volume (MW) for the periods: ▪ 14:00- 14:30 ▪ 14:30-15:00 ▪ 15:00-15:30 ▪ 15:30-16:00 ▪ 16:00-16:30 ▪ 16:30-17:00
From this you would work out the In-day Adjustment (MW)
In Day Adjustment = ∑ (Metered Volume – Unadjusted Baseline Value) / 6"
"3. In-day adjustment (Domestic consumers only)
The in-day adjustment is calculated using the 6 Settlement Periods between Event Time- 4 Hours (E4) and Event Time- 1 Hours (E-1).
For example, if the DFS event happens at 18:00, the E-4 is 14:00 and E-1 is 17:00, the in-day adjustments would be calculated using Metered Volume (MW) for the periods: ▪ 14:00- 14:30 ▪ 14:30-15:00 ▪ 15:00-15:30 ▪ 15:30-16:00 ▪ 16:00-16:30 ▪ 16:30-17:00
From this you would work out the In-day Adjustment (MW)
In Day Adjustment = ∑ (Metered Volume – Unadjusted Baseline Value) / 6"
Soldato
Based on the above and what I have seen, it appears* that for the -4 to -1 window it IS comparing that same window to the previous 10 days as well.
Eg today you use 10kwh between 1-4pm, but normally your average (last 10 days) is 1KWH then they would take 10-1 = 9, /6 = 1.5kwh
The 1.5kwh is then added to each of the half hourly savings session averages.
* one of the problems is they refer to unadjusted baseline value in more than one place in regards to more than one data set.
However from the example they give of what would look like if you tracked it all half hourly in a spreadsheet seems to infer the term is used for each time period in isolation, and that the calculation is not simply based on the initial calculated unadjusted baseline value
Eg today you use 10kwh between 1-4pm, but normally your average (last 10 days) is 1KWH then they would take 10-1 = 9, /6 = 1.5kwh
The 1.5kwh is then added to each of the half hourly savings session averages.
* one of the problems is they refer to unadjusted baseline value in more than one place in regards to more than one data set.
However from the example they give of what would look like if you tracked it all half hourly in a spreadsheet seems to infer the term is used for each time period in isolation, and that the calculation is not simply based on the initial calculated unadjusted baseline value
Soldato
Here is the doc, linked for future use
Calcs are right at the end
Calcs are right at the end
Soldato
Gen 1
Yeah I thought that was more likely, damn that's a real shame, as you've now lost some of the gains you would have had with a working inverter and don't have the better one to show for it.
Soldato
So lets theory craft a little
If you use an additional 1kwh during the in day adjustment window, thats going to cost you 34pence.
The adjustment to each half hourly session in the actual savings session would be Extra/6 = 0.1667 kwh.
So each half hour would have that added, seeing as the minimum session is an hour your guaranteed to get 0.33kwh added to your usage and be rewarded at £3.37/kwh.
So 0.33 x £3.37 = £1.12 give or take.
In a longer session, 4 hours being the max you would get that back many times over.
Potentially a max length session would get you 1.33 x £3.37 or £4.48 less the 34p. Bonkers!
The only minor consideration is that you need to make sure you don't somehow manage to use extra during the actual savings session to wipe out you in day adjustment.
I assume they often will just refurbish one if its something simple like a cap going down or something similar
If you use an additional 1kwh during the in day adjustment window, thats going to cost you 34pence.
The adjustment to each half hourly session in the actual savings session would be Extra/6 = 0.1667 kwh.
So each half hour would have that added, seeing as the minimum session is an hour your guaranteed to get 0.33kwh added to your usage and be rewarded at £3.37/kwh.
So 0.33 x £3.37 = £1.12 give or take.
In a longer session, 4 hours being the max you would get that back many times over.
Potentially a max length session would get you 1.33 x £3.37 or £4.48 less the 34p. Bonkers!
The only minor consideration is that you need to make sure you don't somehow manage to use extra during the actual savings session to wipe out you in day adjustment.
Gen 1
I assume they often will just refurbish one if its something simple like a cap going down or something similar
Soldato
Yeah I posted it above with link to doc, its still potentially slightly murky due to some iffy terminology, but its clearish.
You just missed the adjustment for the baseline. Clarifies its an amount added though and not a % impact.
Sorry I was driving so couldn't reply earlier.
Yes the baseline is an adjustment but for me and others running from batteries probably doesn't influence it.
If I remember the two hour session in December I used 36 kWh and was paid just over £53.
36/6 = 6kWh half hour average multiplied by 4 ( as it was 2 hours saving session) = 24kWh.
This multiplied by £2.25/kWh = £54.
So it's about there, what it's saying is longer saving sessions are more beneficial.
Soldato
Soldato
Yeah for sure.
Was helpful your posting since it made me go and look again and that document I posted above and you screenied was far better than the one that was available a few months ago.
I dont think I am ready to take the mickie on this session but I am going to charge batt to full, and do a load of washing and tumbling.
Ie stuff we would be doing anyway
My battery has been playing up last few nights not charging to full so a nice daytime charge when temp is up slightly might actually get it full again.
Full again being Solaxs definition of full, which seems to be about 75% in reality right now.
Just in time for the real start of the ramp up of generation
and as Hippo says to hax a savings session.Go sign up if you havent already though!
Soldato
Solar here is doing OK so I don't think I can hax them much anyway but I can tell it to hold the charge to 100% until 4pm at least so it won't be eating into reserve until after then.
90% full and solar is generating at 1.8kw.
90% full and solar is generating at 1.8kw.