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Posted

Good day all,

I am not new to the solar adventure - started with a 3.4Kva Mecer inverter, 9x265W panels and 4 lead -acid 200Ah batteries 4 years ago. Accordingly, my expectations and requirements was very basic at the time. I have continuously upgraded as the "requirements" and expectations of the family grew. Through several iterations and evolutions the installation is now as follows :

1. 2 x 10 Kva Kodak OG-10 inverters - coupled with 3x Kodak L1 3.55kw battery sets, each with own BMU obviously - each on to a seperate phase of the house DB

2. 1 x   4.6 Kva Kodak Grid tie - wired into DB - no batteries, supply power on demand

3. 18x265w PV panels , 10x365w PV panels and 8x495w PV panels

In spite of the above - I still end up with half of my house in darkness during load shedding. My question is - is there any reliable technician that I can pay to come and sort out this mess? My experience so far has been, that everyone will sell me more hardware, install it sort-off, set it up to "basic" suppliers settings - never to be seen again. I am not technically minded, have learnt some due to necessity, nut I am ready to go and buy candles  

Any help will be appreciated


 

Posted

What area are you in? We have members all over the country. 

I'm not an electrician but it sounds like plenty solar panels but a little light on batteries. 

Two 10kva inverters are supposed to be paired with around 40kwh batteries. 

I would recommend a diesel generator as a short term stop gap since you can get one for the price of one battery or less.

Others can come in here but it sounds like you have 20kva of offgrid inverters not hybrid( as in split into essential and non essential loads). Which means you are backing up 20kva of loads on 12kwh of batteries. 

Posted (edited)
44 minutes ago, Buyeye said:

What area are you in? We have members all over the country. 

I'm not an electrician but it sounds like plenty solar panels but a little light on batteries. 

Two 10kva inverters are supposed to be paired with around 40kwh batteries. 

Others can come in here but it sounds like you have 20kva of offgrid inverters not hybrid( as in split into essential and non essential loads). Which means you are backing up 20kva of loads on 12kwh of batteries. 

Yes, it does sound light on batteries. Even worse than 12kWh. Those Kodak L1 batteries, seem to be 0.5C, so one can draw only around 6kW from them constantly. And they are paired with 20kva inverters. If there is no sun, and no Eskom, no more than 6kW of load can be supplied. That’s why he ends up with half of the house in darkness during load shedding. 

Edited by PowerUser
Posted

Hi, 

Thanks for the above, I meant two battery banks of  3x3.55kva each. So 10.6kva per bank. 

The problem I am experiencing is not related to elec availability. Both battery sets were at 100% charge, my one inverter just died, the moment the grid went of, the other functions for an hour, then goes offline in 50 second intervals for 5 minutes, then works again until power is restored. 

The WiFi on both inverters died, for no apparent reason, my installer can "come have a look" sometime. 

My avg daily consumption is approx 33kwh for the house, with previous inverters (2x4.6kva Kodak hybrids and 1x4.6kva Kodak grid tie)the max generation was approx 65kw per day. I know this, because I was also exporting to the grid (and paying for the elec flowing back past the smart meter) because the installer could not stop the inverters exporting? 

My consumption at night is around 8kw total, split across the two inverters and battery banks. So there should be plenty to go around. I also have a 16kva three phase generator installed if all else fails. 

Is there anyone in the Randburg or greater JHB area that can help me, to get all this to WORK? 

 

Posted
49 minutes ago, LMJ9175 said:

Hi, 

Thanks for the above, I meant two battery banks of  3x3.55kva each. So 10.6kva per bank. 

The problem I am experiencing is not related to elec availability. Both battery sets were at 100% charge, my one inverter just died, the moment the grid went of, the other functions for an hour, then goes offline in 50 second intervals for 5 minutes, then works again until power is restored. 

The WiFi on both inverters died, for no apparent reason, my installer can "come have a look" sometime. 

My avg daily consumption is approx 33kwh for the house, with previous inverters (2x4.6kva Kodak hybrids and 1x4.6kva Kodak grid tie)the max generation was approx 65kw per day. I know this, because I was also exporting to the grid (and paying for the elec flowing back past the smart meter) because the installer could not stop the inverters exporting? 

My consumption at night is around 8kw total, split across the two inverters and battery banks. So there should be plenty to go around. I also have a 16kva three phase generator installed if all else fails. 

Is there anyone in the Randburg or greater JHB area that can help me, to get all this to WORK? 

 

It sounds like you have enough equipment. 

Posted

@LMJ9175While your consumption is not low , is not exorbitant either. And the fact that the 33KW is divided up into two load sections , each with its own inverter configuration already scales very well .  Those 10kW MAX inverters are more than capable , and your  LFP battery packs well matched.  On face value it could be misconfigured inverters , misconfigured batteries , mismatch between inverter and battery ,  or weird load patterns/demands .  You will have to inform us of your basic inverter settings , basic battery settings . Is your batteries BMS  communicating  to inverter via BMS communication , or do you just use open-ended USER settings ?

Are these  failure modes of the inverters exposed when there is only battery power available , or are both solar and battery power available at the time?

In the long term you also need to consider a half-decent diagnostic logging system , in order to monitor load profiles , battery charge/discharge/sate of charge SOC  profiles ,  solar power  and AC input feed-in power.  Your setup is not trivial , neither is it inexpensive ,  so this is highly recommended  ,  a diagnostic subsystem that is not 'fancy-pants with eye-candy style meters' . With an investment like this you will want to leave little to the imagination.

You can PM me if you have run out of options. I am also in the JHB area.

 

Posted
4 minutes ago, BritishRacingGreen said:

@LMJ9175While your consumption is not low , is not exorbitant either. And the fact that the 33KW is divided up into two load sections , each with its own inverter configuration already scales very well .  Those 10kW MAX inverters are more than capable , and your  LFP battery packs well matched.  On face value it could be misconfigured inverters , misconfigured batteries , mismatch between inverter and battery ,  or weird load patterns/demands .  You will have to inform us of your basic inverter settings , basic battery settings . Is your batteries BMS  communicating  to inverter via BMS communication , or do you just use open-ended USER settings ?

Are these  failure modes of the inverters exposed when there is only battery power available , or are both solar and battery power available at the time?

In the long term you also need to consider a half-decent diagnostic logging system , in order to monitor load profiles , battery charge/discharge/sate of charge SOC  profiles ,  solar power  and AC input feed-in power.  Your setup is not trivial , neither is it inexpensive ,  so this is highly recommended  ,  a diagnostic subsystem that is not 'fancy-pants with eye-candy style meters' . With an investment like this you will want to leave little to the imagination.

You can PM me if you have run out of options. I am also in the JHB area.

 

Your system is scaled by diversity/redundancy  both horizontally and vertically  , so the chances of hardware failure is near zero  , this is true for the inverters and more so for the batteries.

Posted

@LMJ9175I infer you have three-phase grid feed . The fact that you are running  two inverters on two phases , also infers that  each inverter is operated  in single mode / single phase configuration . If that is the case , question is do you have any true three phase loads in your house , example a three phase Air Conditioner . Because if so , it could explain  weird load situations , whereby the inverter's phase angles drifts away when there is no grid to synchronize to (in the case of grid failure).

Posted

Repeating some of the above.

17 hours ago, PowerUser said:

Those Kodak L1 batteries, seem to be 0.5C, so one can draw only around 6kW from them constantly.

4 hours ago, Buyeye said:

Thanks for the above, I meant two battery banks of  3x3.55kva each. So 10.6kva per bank.

I do think you need to review your battery banks. If it's the Force L1 3-pack (https://www.diygeek.co.za/wp-content/uploads/2020/03/Force-L1-Manual.pdf), if this is your battery module, then it's a 10.6kWh rating, not 10.6kVA. Instantaneous Power vs Total Energy, the units are commonly mis-applied. Focus on the spec that you've got a recommended discharge rate of 100A at 48V (45V-54V), and you come back to a maximum ability for the battery to supply around 5-6kW of power, let's say half of the capability that each inverter on each phase might try to draw from it. Exceed that 5kW, and it's likely that the BMS will try to cut back supply and shut off an inverter. 

Beyond that, I'd have to wonder whether your installer set the inverters up for 3-phase operation, especially since there are only 2. On the understanding that this (https://solarbackup.co.za/wp-content/uploads/2021/10/KODAK-Axpert-MAX-II-10K-manual-20210628-OG-10.0.pdf) is your inverter.

And lastly, don't know where the grid-tie inverter fits in, but I'm assuming it's not connected to the output of one of the off-grid inverters, because that wouldn't be able to frequency-shift to control the GTI's output.

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Posted

Thanks, I think any of the above scenarios are possible or a weird combination of all of them.

One of the regular contributers will come and do a proper audit of the system and hopefully we can plot a way forward. 

It also seems that a decent and comprehensive monitoring system can go a long way in identifying the problem.

My gripe with the present situation- some installers seem to do a decent job of safely and correctly installing the hardware.

But they have no real understanding of the interaction between the different components, and how to troubleshoot issues like mentioned above.

Nor so they have the inclination to do so, when faced with a myriad of new installations every day that load shedding continues. 

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