Fellow OCUK hivemind solar peeps I need your help. Some may remember I had issues with my batteries from the start. I have got to the point I really need to escalate the issue with my installers.
I have tried to write an almost letter before action (I am happy to go letter before action but feel this may be enough in itself); in the hope to get them to actually put the time in I suspect they need to in order to fix this. Other than the couple of screen clips does the below make sense ?
Particularly the maths side, I am not that convinced the guys I am dealing with are that good and may struggle to prove/disprove a working system.
I recognise that many people would probably never look at these numbers and just assume its working fine!
I have had to list it all out again as they have a habit of passing it to a junior person who will not have history and end up wasting my time.
I am trying to keep it brief but descriptive enough as to demonstrate the issues, a tricky balance.
Particularly interested in anyones comments in regards the last section (expectations and resolutions)
@kindai would really appreciate your input as well since you have always given good advice in these sorts of scenario.
"Hi Guys,
Unfortunately I think its time now that we must discuss how we can fix this ongoing battery issue once and for all.
Below summary of events, responses given and remedies tried :
1) Pre install I queried the batteries being outside and if that would affect the performance, was confirmed by Gary that his were outside and North facing and no issues.
2) Post install around Nov 30th I queried as to why the system yield for the day was low at around 10kwh, with a small amount of generation included. At that point I had assumed the issue was the conversion loss was very high and that the correct amount of charge had been used in order to fully charge the batteries
I did not comprehend until later it was simply not drawing enough current for long enough in order to be able to actually charge with enough energy to match the declared useable from the specs.*1
At this point Gary logged something with Solax (which they never responded to as far as I know) and I was told it was a system firmware issue.
This was updated by Solax the next day, the BMS and batteries from that point having the same firmware version.
3) I noticed not long afterwards that the same issue was repeating, too little current was being drawn to be able to ever store enough energy to match the useable. This time on query I was told it was due to temperatures and some performance impact due to cold temperatures was normal.*2
This got to the point it was so bad they completely refused to charge at all for a couple of days.
After that I built an insulated cover for the batteries which I had planned to do later anyway to keep them out of direct sunlight. This resulted in the batteries slowly gaining temperature to around 20c.
4) I again queried the fact nothing seemed to have changed in early March to be told in a very confusing email I needed to switch everything off at the CU, (you cannot do this since the matebox means there is no direct connection to the CU for the system only), and that I needed newer firmware again.
I left this until early April since I was on holiday and busy. When I chased I was told in fact I did not need firmware and I could simply tell the system to power off. I have done this again today 24/04 and now the batteries do not display temperature.
I was also given a load of calculations by Christian which do not make sense and worry me he doesn't understand the systems he is supporting (turn off at the CU and the battery should discharge to 0%)
Evidence of system not fuctioning correctly:
Yesterday night (23 April 2023) the batteries went to 10% SOC again. This morning they charged for 1hr 35minutes at around 5.5kw and then another 15 minutes at a declining rate.
At 2:05am after 1hr 35 minutes they said 77%. Having used around 8.71kWh. This having added 67% battery and based on 13.3kwh would be almost the curve you would expect. Needing around 11kWh from 10% SOC to full.
However after this for the remaining 15 minutes of charge the current reduced significantly and the battery went from 77% to 100%.
This would be 3kWh if the system was pulling enough current in 15 minutes or put another way would require a charge rate of 12kWh. Reality was probably around 1.5-2 on average.
See graph below to support above analysis.
Other comments :
This has been really hard work to get taken seriously. I feel like I am being fobbed off with three people having sent responses, on the hope I will go away and stop expecting the battery system to perform as quoted.
The last response last week when I replied to Christian that his calculations were incorrect has not been replied to.
One thing that has sprung to mind is that there was an issue on install day late on when John (I think that was the Electricians name) had to take some of the covers off just as it was getting dark. Something wasnt quite right
but I am not sure what. He unscrewed a couple of the batteries panels from memory but I was not paying that close attention.
I don't feel like I should be required to fault find. Something is up with this battery system and clearly has been ever since it was installed.
A system that the manufacturer claims should be useable down to -30c (see clip below from their brochure) should not be performing this badly in the temperatures we have been having. Again see *2 below. I don't believe it has been, or was ever, setup to operate in low temperature mode.
I do not seem to be able to access the area I was sent a screen shot of so I believe its in the installer menu not the user menu. Maybe someone could confirm, and what setting it is set to use in my case.
Expectations & resolution :
I started down this path before but now I believe it is time that I hand this back to you guys, I need a plan for resolution.
How do you and within what timescale plan to resolve this before I am forced to look at engaging another company to come and fix it. Before recovering costs from yourselves, voluntarily or via the courts.
What I expect is a clear plan. I am happy to undertake some actions as required but the plan needs to be complete not just for the next stage, but a complete list of all actions / activities and right up to a system replacement of parts / whole as required in order to deliver the performance and
specifications quoted not just by yourselves but the manufacturers brochures.
Again I would reiterate that from the raw numbers that can be extrapolated it appears from charge rate * time and discharge "yield" that to me there is a high chance one of the battery modules is faulty and not charging. The performance seems to track very closely to a 3 battery system of 10kWh capacity with 9kWh useable.
Is there a way to specifically test the batteries somehow?
Many thanks in advance, I look forwards to hearing from you in due course.
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*1 manufacturer specs listed as 12.3kwh nominal with 10% minimum SOC giving 11kwh usable. (Sometimes they quote 11kWh sometimes 11.1kWh it seems)
*2 This despite the manufacturer claiming they are tested to super cold temperatures. It seems the fact that the batteries need to have the heating switched on and is only seemingly in the app for installers was not mentioned. I am still waiting for a reply from Christian to confirm this, but it looks like it
Since the screen shot he sent me from the app looks like sits within the installer only options, such as limiting export."
photos.app.goo.gl
