2 hours ago, Coulomb said:

Wow! Those cables really were overloaded then.

Err, since you've just changed the wiring, wouldn't it be more likely to be a wiring issue? Or some breaker not enabled?

Edit: IF your inverters are properly paralleled with parallel boards and cables (comms and current sharing cables), assuming an Axpert-like setup, then the two inverter should be running the same settings, EXCEPT for current related settings. These are allowed to be different between the paralleled inverters. So check settings 02 (maximum charge current), and 11 (maximum utility charge current). If you have say 30 A max one and 40 A max on the other, then you have 70 A max total.

Apologies, I forgot to mention this is not a new problem and has been happening intermittently since it was installed so its hasn't been caused by the wiring.

I have checked and the Max Charge Current (07 setting on mine) is 45A on both. Max utility charge current (28 setting on mine) is also 45A on both units.

All settings are identical on both inverters with the exception of The Model ID Setting, which is obviously 1 & 2.

It's always the same inverter that does it. You can see in the graphs below how it just stops producing at random times. The other inverter never does that.

Edited July 10, 20224 yr by LCG

21 hours ago, LCG said:

Max Charge Current (07 setting on mine) is 45A on both.

Ok, these must be less Axpert-like than I thought. I'm afraid I don't even understand your graphs.

7 minutes ago, Coulomb said:

Ok, these must be less Axpert-like than I thought. I'm afraid I don't even understand your graphs.

Perhaps the low yield on 08-july-2022 to be read with posting yesterday @ 12h48 with 1 inverter producing no PV

So I have been monitoring the system for a few days now. What seems to be happening is when the batteries reach full charge the one inverter stops supplying solar input and when the draw drops below a certain level, the other inverter stops supplying solar and starts supplying from battery. 

This causes a big dip in the batteries just before sun down and its really silly because there is still a fair amount of solar power available when this happens.

What would cause this to happen?

42 minutes ago, LCG said:

What would cause this to happen?

> 2 x 5kw SRNE Inverters

My guess is that these don't operate exactly like the Axperts that they are clearly copied from. Real Axperts unify the charge parameters, and the master and slave(s) operate in the same charge stage at all times (e.g. both bulk, both absorb, both float, or both not charging). It sounds like these are operating more independently.

Are there cables between the inverters expressly for the purpose of paralleling them?

The other thing is that the inverters may have significantly different measurements of the battery voltage. So one might think that the battery is full enough, while the other thinks it has a ways to go yet. I have published commands to calibrate the battery voltage measurement for Axperts, but with these SRNE inverters, who knows if those commands would work. If you're keen to try it, see this post. But first, you might want to convince yourself that differing voltage measurements is at least partially the cause of this issue. Just watch the battery voltages as reported by the two inverters at various times of the day: low and high load, low and high charge current, etc. It's hard to watch two things that change quickly at once, but you should be able to compare them when things aren't changing too fast. They should ideally agree most of the time to within 0.1 V. Of course, if the measured voltage is alternating between two values (say 52.4 and 52.5), then you can't expect the other one to match that voltage exactly. But if one is solidly on 52.4 and the other solidly on 52.6 say, then that could be improved with calibration, and might help your problem.

It's possible that battery cable wiring is making things worse, either by the cables being too thin (and thus having excessive voltage drop across them), or different lengths, or poor wiring arrangement, or a combination of several of these. If you find a solid difference such as my last example, check at the battery terminals of each inverter, to see if the difference is due to cable voltage drops.

Thank you once again for your amazing input. Ill check the voltage readings over the weekend. 

Based on the way these guys wired these I would say there is definitely a difference in length between the supply lines. 

I took the below image while they were installing. The batteries essentially connect to one inverter, then there is a loop to the second.

 

Edited July 14, 20224 yr by LCG

1 hour ago, LCG said:

Thank you once again for your amazing input. Ill check the voltage readings over the weekend. 

Based on the way these guys wired these I would say there is definitely a difference in length between the supply lines. 

I took the below image while they were installing. The batteries essentially connect to one inverter, then there is a loop to the second.

 

This is what @Coulomb

Was referring to. Both inverters will see different voltages due to the loop from 1 to 2.

The 1st thing I would do is to get battery leads of the same length from battery terminals to each inverter. See then if there is an improvement.

2nd would be to see what values each inverter measures as is indicated by Coulomb.

I saw a video from the U.S. where they installed my exact batteries, with one set of battery leads to the first inverter from the top of the bank, and one set of leads from the bottom to the bank to the second inverter.

 

The reasoning was that it balances the batteries better that way?

Should I consider doing it that way or is that pointless?

6 hours ago, LCG said:

Should I consider doing it that way or is that pointless?

Not pointless at all. Except that I'd wire a little differently, diagonal take-off and diagonal landing†. Like this:

As long as you make the cables to the inverters the same length, there is no difference between either inverter's access to either battery. If you have more than 2 batteries, just daisy chain them as usual, and use the same connections at the top and bottom. All these cables should be 25 mm² minimum (e.g. what comes with or made for Pylontech batteries).

†Edit: in retrospect, diagonal landing isn't really the right term. Perhaps "dual diagonal take-off" would be more appropriate.

Edited July 15, 20224 yr by Coulomb

7 hours ago, LCG said:

I saw a video from the U.S. where they installed my exact batteries, with one set of battery leads to the first inverter from the top of the bank, and one set of leads from the bottom to the bank to the second inverter.

 

The reasoning was that it balances the batteries better that way?

Should I consider doing it that way or is that pointless?

My reason is if there is a problem TRY SOMETHING and see if it does not produce a positive result. Not all videos published show wiring the correct way.

Good day folks. 

So I figured it is about time I give a bit of an update on this system of mine. 
 

Despite the initial snags I experienced, I seem to now have found a good balance and things are working well. 

After running a second string of wires from each bank of 12 panels everything seemed to improve and everything is now running much cooler. The voltage is much higher and the amps are lower.

My inverters seem rather different to the main stream stuff and I have pretty much had to figure out my settings by trail and error. 

What irritated me most was that my batteries would be depleted by around 2:00AM and then the system would charge the batteries on mains. So when the sun came up I had full batteries and was wasting solar power. 

I have now got the system on SBU, with OSO as the charge option. The system now runs on battery at night until 50v and goes over to mains, Leaving 6v in reserve for potential load shedding. It then stays on mains until the batteries get back up to 52v in the morning and then starts supplying the house with solar power. 

Bearing in mind that I normally use 50kw - 60kw a day at this time of year. I am now only using 7kw - 10kw of mains power, which in my opinion is fantastic. 

Yesterday the system generated 45kw of solar power. 

I have swapped the geyser element in the cottage to a 2kw to bring the peak load down which has helped massively.
I have also had a 5.4kw ITS heat pump installed on 2 x 150lt geysers connected in series.  The heat pump runs approximately 3.5 - 4 hours a day and despite my families best efforts, we have not run out of hot water yet. The heat pump does not run outside of that programmed daytime slot at all.

I still need to run equal length battery cables and install the disconnects and will do this as soon as I can. The inverters are getting a slightly different voltage reading with the different length wires. I don`t know if this is causing any issues, but its worth fixing. 
 

I do realise that with the charge option on OSO I may get caught out if there is a lot of load shedding and a number of overcast days in a row, but I do have a generator and can always switch to UTI to charge the batteries if things are getting tight. On the upside my depth of discharge isn't as low which can only really be a good thing for my batteries. 

I'm still considering running hot water supplies to the dishwasher and washing machine to lesson the water heating times but I don't know if that is worth the effort at this stage. It will lessen the initial heating time, but they still heat the water constantly during the cycles.

Sometime before next winter I still want to get the current east facing panels pointing North. This will require some creative brackets and fabrication work, but it is possible. This should increase my winter production quite a bit.

Thanks again to everyone here who offered their invaluable input. I could not have gotten this thing right without you folks. 

Edited August 24, 20223 yr by LCG

Over the last three days I have used absolutely ZERO mains power! 🍾

2 hours ago, LCG said:

Over the last three days I have used absolutely ZERO mains power! 🍾

Good to read how happy things turned out and what power you getting from PV. 😃😃