Solar panels and battery - any real world reccomendations?

john_smith said:
ok. A good day yesterday. We set to charge to 85% over night and then the PV took us to 100% during the day.

Is this normal though? Do they struggle to report SOC?

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Do you have Solax as well, thats the result that I see as well, a massive jump in SOC. Although for me its consistent at around 73-74%, it then jumps to 99% over about 10 minutes and settles to 100% soon after.

Initially I thought it was other issues, but when I saw a day when the batteries charged at 5.5kwh for about 1hr 40 I went huh!?
I checked and it was the same constantly, they never draw enough power to be able to provide the 11kwh they are supposed to. (System is 12.3kwh but 11 useable due to DOD)
It seems the actual output is around 8.4kwh (give or take), but with input around 9.2(ish). So the conversion loss is about right especially if as i suspect they are, they are heating a bit. There is supposed to be a setting I am told, but can't find it for battery heating on/off.
I will get some serial plates photos today to see if i can work out exactly what the batteries are, manu dates etc. Since I believe Solax did an older version of 3.1kwh and well as a newer one.

I had kind of given up getting anywhere in the short term with the temps being blamed for the battery performance, but it seems the batteries are sitting well above zero constantly now after I added insulation and nothing is any differernt.
Delving into the specs a bit more it looks like with battery heating on they should work down to -30, with it off they will draw down to -10, but only charge if above zero.
I was assuming I was going to have to wait until March time to get some decentish temps overnight so they could stop blaming the temps.
I know there will be some effect from temps, but this just seems to consistent when temps are varying by like 15c between when it was installed and the coldest point since installation.

None of this really to me explains the big gap though since it seems to be constant. (Quoted vs actual performance)

The thing they ignore every single time I try to question is that a 3 battery system quotes useable battery of 8.4kwh, basically smack bang on what I am getting, but they refuse to entertain that something is up and I could only be running on 3. Based on the fact the system can see 4.

I also get a similar dramatic line when it gets to around 25%, with I think no more than 0.4kwh being delivered from the batteries between 25% and 10%.

I am going to try to nag Solax UK some more.
 
Above is not Solax it's GE. There is a big thread on SOC issues on the GE community forums.

I have not really seen any myself but I cycle the battery constantly. Go charge, full empty most days in the winter, charge back to full etc.

From what I can tell people who have the most SOC issues are issues are those who had the battery idle for a long time.

That's why I said charge to 100%, get the battery hitting the upper capacity limits.
 
HungryHippos said:
Above is not Solax it's GE. There is a big thread on SOC issues on the GE community forums.

I have not really seen any myself but I cycle the battery constantly. Go charge, full empty most days in the winter, charge back to full etc.

From what I can tell people who have the most SOC issues are issues are those who had the battery idle for a long time.

That's why I said charge to 100%, get the battery hitting the upper capacity limits.
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Yes, this battery has been flat for nearly a month. Lets see if it continues now it's been to 100%
 
HungryHippos said:
Above is not Solax it's GE. There is a big thread on SOC issues on the GE community forums.

I have not really seen any myself but I cycle the battery constantly. Go charge, full empty most days in the winter, charge back to full etc.

From what I can tell people who have the most SOC issues are issues are those who had the battery idle for a long time.

That's why I said charge to 100%, get the battery hitting the upper capacity limits.
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Makes sense since the battery has to stretch itself to work out what its lost. I think they derive this from voltage/ampage in that as the batteries get close to max they lose the ability to charge.

I would assume a full charge and full discharge or vice versa is the only real way the batteries can fully calibrate themselves accurately.
Probably discharge first is best, then charge from empty. This is the GE commissioning process isnt it? Dump battery, charge to full?
 
Yes when I got the battery it did full discharge, then full charge, then full discharge again I think. It came with a little capacity.

You may be able to sort or mimic this by doing a timed export to get the battery down to zero by the start of the Go period, then a full charge back up to 100% within Go window.
 
I'm going to monitor for a while over this sunny period. He has 2 x 9.5 batteries. Do they present as a single entity or can 1 be emptied down and independently charged to 100? As they only charge at 2.5 we can only get to 10 within go.
 
john_smith said:
I'm going to monitor for a while over this sunny period. He has 2 x 9.5 batteries. Do they present as a single entity or can 1 be emptied down and independently charged to 100? As they only charge at 2.5 we can only get to 10 within go.
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Generally they are combined as one entity, and if wired correctly should discharge and charge equally, if the cables are different lengths or sizes then the one with the lowest resistance connection will discharge and charge quicker.

Cant see why they'd want to discharge one then the other, that will just mean one will wear out quicker than the other, so most likely to be one entity.
 
Ron-ski said:
Generally they are combined as one entity, and if wired correctly should discharge and charge equally, if the cables are different lengths or sizes then the one with the lowest resistance connection will discharge and charge quicker.

Cant see why they'd want to discharge one then the other, that will just mean one will wear out quicker than the other, so most likely to be one entity.
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TY.

I was thinking just as a one off discharge / charge rather than running like them continually.
 
Is anyone going to try and erm "optimize" for the big energy saving session later, at £3.37kwh saved on Octopus.
I saw one person on here who was convinced the majority of the "savings" calc was based on comparing use between -4hours to -1hour to the savings hour to useage in the savings hour. (They achnowledged that the calc had a longer tail that including considering the same time window on previous days as the savings window but that it was largly weighted towards that -4hrs to -1hr preceeding window).
So on that basis it would be benefical to discharge fully this morning to make room, then fully charge in that 3 hour window starting at 1pm today before the 5pm savings session, for a maximum profit of £2.97 kwh (less due to how the "savings" comparator is actually calculated).
Wondered what thoughts were on this?
 
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SBo said:
Is anyone going to try and erm "optimize" for the big energy saving session later, at £3.37kwh saved on Octopus.
I saw one person on here who was convinced the majority of the "savings" calc was based on comparing use between -4hours to -1hour to the savings hour to useage in the savings hour. (They achnowledged that the calc had a longer tail that including considering the same time window on previous days as the savings window but that it was largly weighted towards that -4hrs to -1hr preceeding window).
So on that basis it would be benefical to discharge fully this morning to make room, then fully charge in that 3 hour window starting at 1pm today before the 5pm savings session, for a maximum profit of £2.97 kwh (less due to how the "savings" comparator is actually calculated).
Wondered what thoughts were on this?
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Yes, made £53 on the two hour session
 
I have tried the optimisation of the Saving Sessions before (earnt about £16 so far), admittedly I thought it was based on your usage in that time period on previous days and had been deliberately charging in those periods, but gave up when I switched to Economy 7 as it became less worthwhile (and there seemed to be fewer sessions), but if it's also based on the hours beforehand then might be worth pausing my battery solar charging today and doing some grid charging later (Agile export price is pretty good all day, so would earn a bit from that as well).
 
Tavis75 said:
I have tried the optimisation of the Saving Sessions before (earnt about £16 so far), admittedly I thought it was based on your usage in that time period on previous days and had been deliberately charging in those periods, but gave up when I switched to Economy 7 as it became less worthwhile (and there seemed to be fewer sessions), but if it's also based on the hours beforehand then might be worth pausing my battery solar charging today and doing some grid charging later (Agile export price is pretty good all day, so would earn a bit from that as well).
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It's not just 1 or the other I think it's a combination of both historic usage from range of days before and usage from -4 to -1 hours before the session.
 
HungryHippos said:
It's not just 1 or the other I think it's a combination of both historic usage from range of days before and usage from -4 to -1 hours before the session.
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Correct

Average for the session is based on previous 10 week days, excluding previous sessions and bank hols. (in a weekday case). Weekends work slightly differently but unlikely to be sessions on weekends IMO.

Then there is an adjustment to this baseline, its based on a three hour window on the day that is upto 1 hour prior to the session. (ie session start time -4 to -1)
Exactly how the adjustment influences the baseline though is hard to find. The NG stuff i found just says it is there to adjust for that days load, but with no specific example of how it affects your revised baseline.

Its to reflect that a day could be high (or I assume low usage). Eg you may be heating with elec as its cold, so in effect your saving more during the saving session. Vice versa I assume its also to not reward you if your on hols and of course using far less for example.
 
Mercenary Keyboard Warrior said:
Correct

Average for the session is based on previous 10 week days, excluding previous sessions and bank hols. (in a weekday case). Weekends work slightly differently but unlikely to be sessions on weekends IMO.

Then there is an adjustment to this baseline, its based on a three hour window on the day that is upto 1 hour prior to the session. (ie session start time -4 to -1)
Exactly how the adjustment influences the baseline though is hard to find. The NG stuff i found just says it is there to adjust for that days load, but with no specific example of how it affects your revised baseline.

Its to reflect that a day could be high (or I assume low usage). Eg you may be heating with elec as its cold, so in effect your saving more during the saving session. Vice versa I assume its also to not reward you if your on hols and of course using far less for example.
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So if your previous 10 week days is close to 0 and your 3 hour adjustment window is (say) 9kwh so 3kw/hr, and your use during the savings window again close to 0 then we will be able to work out the adjustment factor. 100% would gross you £10.11 today, with costs of £3.60 from the 3 hours of charging.
 
Mercenary Keyboard Warrior said:
Correct

Average for the session is based on previous 10 week days, excluding previous sessions and bank hols. (in a weekday case). Weekends work slightly differently but unlikely to be sessions on weekends IMO.

Then there is an adjustment to this baseline, its based on a three hour window on the day that is upto 1 hour prior to the session. (ie session start time -4 to -1)
Exactly how the adjustment influences the baseline though is hard to find. The NG stuff i found just says it is there to adjust for that days load, but with no specific example of how it affects your revised baseline.

Its to reflect that a day could be high (or I assume low usage). Eg you may be heating with elec as its cold, so in effect your saving more during the saving session. Vice versa I assume its also to not reward you if your on hols and of course using far less for example.
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It takes the half hour average from the 3 hour session multiplied by the number of half hours in the savings session
 
94JDH said:
It takes the half hour average from the 3 hour session multiplied by the number of half hours in the savings session
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Have you got a source for this part since I couldn't find it on the NG stuff.
If this is how its working the in day adjustment is more significant than the history data which would seem a bit odd.

SBo said:
So if your previous 10 week days is close to 0 and your 3 hour adjustment window is (say) 9kwh so 3kw/hr, and your use during the savings window again close to 0 then we will be able to work out the adjustment factor. 100% would gross you £10.11 today, with costs of £3.60 from the 3 hours of charging.
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Im not sure.

The main factor is supposed to be the savings in the session itself. See above on what 94JDH says, I'm not sure if thats right or not, I can't find where NG specifically say how they make the adjustment.
 
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