More battery capacity does give the ability to dump more to the grid during peak rate if you're on Flux. I have an 8.2 but would probably go for a 9.5 if I was getting the system now, think the 9.5 is also slightly more up to date tech wise and has a few other benefits IIRC
Solar panels and battery - any real world reccomendations?
- Thread starter GinG
- Start date
Soldato
Sure I'd like the 9.5 as well tbh, but the 8.2 does alright!
My Inverter is only G1 as well which is limited to 2.6kW when sun isn't shining, if sun is out then it can direct 2.6kW from battery as well as another 2.6kW from solar to house load.
Associate
Battery and inverter installed finally:
However panels currently stacked in the middle of my garage due to high winds and amber weather warnings in my area again.
Think it will be into middle or end of next week looking at the forecast before they go up.
Both battery’s at 5.8kW, I assume one is larger than the other as it’s a main and the other a slave so some extra gubbins.
However panels currently stacked in the middle of my garage due to high winds and amber weather warnings in my area again.
Think it will be into middle or end of next week looking at the forecast before they go up.
Both battery’s at 5.8kW, I assume one is larger than the other as it’s a main and the other a slave so some extra gubbins.
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Soldato
Anyone run a solar iboost and AC coupled battery together?
When I installed it was doing some odd things, but from what I understand the AC battery inverter (givenergy) has a 100w threshold, and the iboost was also at 100w.
Changed the iboost to 200w and all ok, at least for a few weeks.
Today it's a lot sunnier than it has been, and I've been watching it this morning, and although not constantly, it's been "mostly" diverting to the iboost over the battery.
I tried setting the threshold on the iboost up further to 300w but doesn't seem to have changed anything.
Any ideas at all?
I'm pretty sure there isn't any issue with the battery as such, as it has been occasionally charging, and discharging correctly under high draw, kettle & dishwasher heat cycle.
When I installed it was doing some odd things, but from what I understand the AC battery inverter (givenergy) has a 100w threshold, and the iboost was also at 100w.
Changed the iboost to 200w and all ok, at least for a few weeks.
Today it's a lot sunnier than it has been, and I've been watching it this morning, and although not constantly, it's been "mostly" diverting to the iboost over the battery.
I tried setting the threshold on the iboost up further to 300w but doesn't seem to have changed anything.
Any ideas at all?
I'm pretty sure there isn't any issue with the battery as such, as it has been occasionally charging, and discharging correctly under high draw, kettle & dishwasher heat cycle.
Soldato
Funny I was talking to the spark from my install last week (battery swap again, must update on that)
He was talking about how sensitive or not the little clip on sensors are, and of course I mentioned the CPU speed, because a little processor needs to detect the current and switch the circuit depending on a few factors.
I suspect your iboost is just faster to monitor and detect the current and hence it is grabbing it before the batteries see the excess current.
I would make sure the battery is closest to the inverter, and the iboost as far away as possible, give yourself max chance the battery sees the excess fastest.
The problem is, its not the excess limit being higher its that the iboost is reacting faster.
You can check your battery by stopping the iboost (remove battery from sender or switch off at main by your tank).
What your really want is a delay on the iboost, say 10 seconds before it kicks in.
Its one the minor drawbacks with AC coupled being disconnected from the inverter.
He was talking about how sensitive or not the little clip on sensors are, and of course I mentioned the CPU speed, because a little processor needs to detect the current and switch the circuit depending on a few factors.
I suspect your iboost is just faster to monitor and detect the current and hence it is grabbing it before the batteries see the excess current.
I would make sure the battery is closest to the inverter, and the iboost as far away as possible, give yourself max chance the battery sees the excess fastest.
The problem is, its not the excess limit being higher its that the iboost is reacting faster.
You can check your battery by stopping the iboost (remove battery from sender or switch off at main by your tank).
What your really want is a delay on the iboost, say 10 seconds before it kicks in.
Its one the minor drawbacks with AC coupled being disconnected from the inverter.
Soldato
Yup I think you are right.
The iboost "reacts" faster then the battery inverter, as it draws it stops anything being detected by the battery CT clamp.
I've upped the threshold on the iboost to 500w and seems a little better this afternoon, although it may be the hot water is up to temp, and typically.... It went cloudy after so hard to tell for sure.
I'll keep an eye on it.
Hopefully not, but it may be a case of having to disconnect the iboost over the winter months which would be a bit annoying, but obviously it's very inefficient to have the excess heating the water over the battery.
Soldato
It will likely help unless you get very "sun in" "sun out" type weather
Because at 500w on the iboost then the battery will kick in if it sees say 350w, at that point the iboost sees zero after seeing 350w for an instant
If another 300w becomes available again the battery will take it, now taking 650w, iboost sees zero after seeing 300w again for an instant
But if its cloudy then suddenly 1.5kw appears its likely the iboost will grab it first
What export tariff are you on? As I am on 8p now my iboost is off again anyway. I just use it when we get the free energy sessions.
Gas assuming 85% efficiency needs to go above 7p or so before I will prefer to send solar excess to tank as opposed to export
Soldato
12p per kWh with Scottish Power.
We have oil fired heating here not that it makes that much difference I suppose.
I'll keep an eye on it over the next few days, thanks for your help though.
Soldato
@BUDFORCE Just a guess here, but if using home assistant, could you put a relay in the CT clamp circuit, so if the battery is full, the relay reconnects the CT clamp, and then the iBoost uses the excess.
Think I've also heard of two CT clamps in series, one on the feed to the AC battery the other on the mains so it sort of cancels out, and thus the iBoost see's the true excess.
Think I've also heard of two CT clamps in series, one on the feed to the AC battery the other on the mains so it sort of cancels out, and thus the iBoost see's the true excess.
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Man of Honour
Oh no, not another one
any improvement?
Soldato
Oh no, not another one
You force me into an update
These were batteries 10 and 11 in the saga. Solax support identified two as under performing. Bearing in mind they were replaced around 2 months ago with completely new ones.
The day after they were fitted they advised, all good. Based on what they consistently do, take the SOC, add the charging rate and calculate the supposed SOC.
But as ever, I have had to prove like 10 times now that the SOC is basically a lie. Its an estimate and at times its a completely nonsense one.
The only true test is a full charge or discharge cycle. 10-100 or 100-10
So the last 3 days I checked after install we had AC (grid) usage of 10.4kwh, 10.8kwh and 10.1kwh. Battery "addition" was 9.8kwh, 10.2kwh and 9.5kwh. efficiency was 94.1%, 94.4% and 94.2%
No way they are ever going to give usable 11kwh (I know this will suffer loses as well) if you cannot even send 11kwh to the batteries pre losses.
With that efficiency loss you need something like 11.6kwh from grid. And you should expect around 10.4kwh actual output.
Output is more of a pain to calculate but its around 9.5 from what I can see quickly.
I have given them until Friday when I will 1) advise trading standards I believe the product is sold in the UK with misleading data; and 2) complain to the RECC about the same.
Depending on that RECC decision I may need to go legal.
I am pretty certain that with 11 batteries now having been tried they have to accept there is an issue.
My proposal to them will be, choices of :
1) Replace the batteries at their cost with 3x the 5kwh ones (newly released) so that at least I can expect 11 usable based on expecting worst case similar performance.
2) I may be willing to contribute nominally to above on proof, if they meet listed specs, within say 2%.
3) Compensation of £1250 (expecting they would counter offer lower) in acceptance of at least 10% under performance of batteries and that this will cost me increasing amounts as the 10 year life ticks by.
4) A full refund and removal of system, making good all damages.
Soldato
Here's an interesting titbit for you, as you know I have two home built batteries, both batteries have a BMS, the BMS works out a SOC. This is not used anywhere in my system.
For real SOC I have a Lynx shunt, you tell the shunt the total ah capacity of all the connected batteries, which is 560ah. The shunt counts the ah in and out, and from this it knowd the SOC.
Now last week when the batteries hadn't had a full charge for days, both BMS's were showing 70% SOC, the shunt was significantly lower, can't remember what it was but it was certainly less than half.
I've also had it where one BMS reads significantly different to the other, other times they both agree with the Victron shunt.
Andy, on the off grid garage, always says to go by only the shunt, and ignore the BMS SOC, he's right.
So depending on how they calculate SOC it can clearly be inaccurate, especially if just going by voltage.
Soldato
The other big problem is a lot of battery management systems will show 100% SOC if a cell goes over voltage, whilst others aren't anywhere near full., and if a cell goes over voltage charging stops.
Soldato
Thanks mate, yes agree, I watch him as well and this has been my conclusion all along.
I have also seen that the various SOC controllers can also vary with some being better than others at getting it right.
They are probably good enough if the cell quality is also good enough (and well balanced at the start)
Yep, the guy you mention above has showed this a few times. I think its generally far less of an issue with an active balancer but even so remains an issue.
We have previously performed a balancing mode on my system. It spend 48 hours. It would trickle charge, then dump a bit, then trickle charge, rinse repeat.
Made no difference at all.
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Soldato
Solax support coming up trumps again
"Hi xxxxxxx,
The battery is not an ideal device, so there will be some energy loss due to electrical-chemical or chemical-electrical energy conversion.
And, low temperature can also significantly influence the battery performance, we all know how the EV cars perform in the cold weather.
We noticed that, during the battery charging in the early morning, the battery cell temperature was around 12 degrees.
Finally, it shall be noted that all the battery parameters shown in the specs sheets are obtained under laboratory environment with strict power/pressure/temperature requirements. Change of testing environment can also influence the testing results.
We confirm that all the batteries are working normally.
Thanks."
"Hi xxxxxxx,
The battery is not an ideal device, so there will be some energy loss due to electrical-chemical or chemical-electrical energy conversion.
And, low temperature can also significantly influence the battery performance, we all know how the EV cars perform in the cold weather.
We noticed that, during the battery charging in the early morning, the battery cell temperature was around 12 degrees.
Finally, it shall be noted that all the battery parameters shown in the specs sheets are obtained under laboratory environment with strict power/pressure/temperature requirements. Change of testing environment can also influence the testing results.
We confirm that all the batteries are working normally.
Thanks."
Soldato
Then you'll know that a lot of BMS's have a very poor balancer, that either doesn't work, or makes matters worse.
I'm not sure how much energy you're missing, but there can be significant losses, my consumption goes up way more when I'm charging the battery at maximum power.
Soldato
Its taking around 10.5kwh from the grid when battery is at 10% SOC. To charge to 100% SOC.
It needs around 11.6kwh input in reality to give me 11 useable. IE if capacity is 12.3 then 90% is 11.07kWh multiplied by the efficiency I see (94.5% or so) then I get 11.6-11.7kWh to be drawn from the grid to give me realistically 11 actually added.
The battery added number is around 9.8-9.9kWh on the portal, hence the 94.5% approx efficiency. Because I am falling 1kwh or so short in input then I am falling 1kwh or so short on capacity added to the battery.
Then on usage I see around 9.4(ish) Which makes sense since 9.9kwh in * 95% is 9.4kwh so again seeing around expected 5% loss.
Yeah it was after watching many of his vids that I realised how much of a lottery this was and how if they had a bad cell, or variable cell quality you have practically no chance of getting expected output if they have calculated the absolute perfect value from stats sheets.
Man of Honour
It does show how much value there is in decent support and honesty when it comes to the manufacturer's tolerances but i'd imagine its like any industry where they push the 'true' as far as it can go to keep competitive (for example diesel gate etc.)
In associated news I'm in the middle of a powercut here and only know about it because the battery breakers make a hell of a din when they cut over and the inverter is now beeping ever 5 seconds to tell me
In associated news I'm in the middle of a powercut here and only know about it because the battery breakers make a hell of a din when they cut over and the inverter is now beeping ever 5 seconds to tell me
Soldato
It does show how much value there is in decent support and honesty when it comes to the manufacturer's tolerances but i'd imagine its like any industry where they push the 'true' as far as it can go to keep competitive (for example diesel gate etc.)
In associated news I'm in the middle of a powercut here and only know about it because the battery breakers make a hell of a din when they cut over and the inverter is now beeping ever 5 seconds to tell me
Agree and the installer to be fair to them have been very good.
They are clearly not the experts and rely on the manufacturer for batteries. The manufacturers support is IMO poor.
They regularly misrepresent stuff, I am not sure from lack of knowledge, or to try to make the situation go away.
It was mildly amusing this afternoon. UK support sent me the stuff about it being cold.
I sent them back the details I had from China that they were unaware I had.
Where China support said they had spoken to the battery designer who said the heating only works from 10C and below, since that is when it is needed.
I got a "oh can we have your communication with China emails please!"
I also have an email from the installers, one of the directors, who told me they have never had any charging/discharging difficulties and they install around six battery systems a week. And his batteries are on a north facing wall and have no issues.
I can certainly represent that I was given the impression there would be no issues in regards the batteries. I raised this query after reading the spec sheets that mentioned charge temps of 0c and above.
Anyway holding out to see if they advise anything in regards my offer.
Otherwise its redo the case and submit to RECC over the weekend.
Soldato
I'm a bit undecided on whether to force export some power, or save it in case we get a power cut, although that's extremely rare.