My solar input is flickering around like mad. It will show 2000W generation then a second later 1500W then back to 2000W then 200W for a fraction of a second, it's all over the place. This is not due to cloud, happens in clear blue sky. When it is at 2000W that is where it should be, when it has fallen down to lower it looks like some solar is being wasted somehow.

It happens a lot, I reckon I am losing at least a few percent of my total generation. Mostly happens in middle of sunny days.

I did wonder if it was the battery not accepting the solar, but this also happens sometimes when load is greater than solar input, so perhaps not. Certainly if the battery is full solar input displayed falls, as I don't sell back to the grid.

I suspect the inverter a bit, but replacing the inverter would be a case of the medicine being worse than the illness given the cost and hassle. It's also not going to be worth spending hours and hours on this, or paying for a professional to look at this, at least not for now.

I am also a little worried about the affect on the inverter lifetime of having the solar input constantly jumping about the place. It makes more noise when this is happening and seems to be working harder.

Any idea what's going on? Or ideas to fix? Or does this error/behaviour have a name so I can google it for more info?

 

Edited February 10, 20233 yr by Green Power

Here is a video:

https://vimeo.com/manage/videos/797553667

(Please ignore the flashing number 4 error. That is a low battery warming that wrongly happens all the time, I think because this inverter was designed to work with lead acid batteries so it just correlates something like 48V or 49V = low battery which doesn't make sense for the lithium batteries it is currently working with. This flashing error is almost certainly nothing to do with the solar input variation so don't be distracted by this.)

What inverter do you have and maybe a firmware update will help.I had some odd pv drop offs on 1 of my mppts.I did and update and all sorted

A firmware update is worth looking into. I will check it out. The inverter is: Axpert MKS II 5kW

UI 71 80 is what appears on the inverter and I think is the firmware. I think I discussed this with @Coulomb once.

Does this look right:.It is 2021 so maybe we need something like this but more recent.

Not sure how you actually update firmware. I assume you need the right cable to connect a laptop to the inverter. Is there someone with basic instructions?

 

Edited February 12, 20233 yr by Green Power

15 hours ago, Green Power said:

Does this look right: It is 2021 so maybe we need something like this but more recent.

The MKS II with no removable panel and no round LED ring and colour display is now an older model. So the 2021 firmware 71.86 is in fact the latest that there is for that model.

15 hours ago, Green Power said:

Not sure how you actually update firmware. I assume you need the right cable to connect a laptop to the inverter.

Yes, your model (like mine) can only be updated via a USB to RS-232 adapter, and the D9 to RJ-45 cable that came with the inverter.

15 hours ago, Green Power said:

Is there someone with basic instructions?

Yes, here: Firmware upload instructions. Ignore the section at the end about SCC firmware updating; your model doesn't have separate SCC firmware.

Have you checked your PV wiring? all tight? maybe bad MC4 connection?

What about your load during this fluctuation? is it happening on stable load? 

Is you PV voltage doing the same?

Yes, stable load. Voltage also seems to be OK, but haven't watched closely. Good idea on the wiring but everything looks OK to me, not that I'd necessarily be able to tell.

Do I really need to set the loads to zero to Coulomb for the firmware update to work? Can I at least leave the internet box on and have a low load of 30 or 40W? I want a low carbon lifestyle to be attractive to my family and others, if it's really necessary to set loads to zero I'll probably wait until the next time I will be at home alone to do the firmware update. That would be mid to late March most likely.

Is there any significant chance at all that the firmware update will make this work, or cause the inverter to stop working? Or is the realistic worst case scenario that it doesn't work and I'm just back where I started?

 

Edited February 13, 20233 yr by Green Power

16 hours ago, Green Power said:

Do I really need to set the loads to zero, Coulomb, for the firmware update to work?

I suppose you could leave a small load on. But during the firmware update, the firmware isn't running, only the bootloader, so it can't generate any sine waves. So there will be no power on the output, no lights will flash, display will be frozen, etc. Make sure your computer doing the update doesn't rely on power from the inverter.

16 hours ago, Green Power said:

Is there any significant chance at all that the firmware update will make this work, or cause the inverter to stop working?

I have a firmware update for 71.82 that has in the file name "correct PV MPPT", so it sounds like there was an issue, and it was fixed in that version. Obviously that fix carries over to all laver versions, including 71.86.

As for the chance of the inverter not working, nothing is totally certain in life other than death and taxes, and we might cheat death one day. But the chances of bricking the inverter are low. The main issue is the state of the opto-couplers. The parts used are marginal at 9600 bps (the speed needed for firmware updating), and the parts do degrade over time. Even so, the risk is low, and even if an update fails, it's usually possible to retry and succeed on the next try or the one after that. The communications board is replaceable at modest cost in the rare case that it's necessary. It also helps to use a known-good USB to serial (RS-232) adapter.

Thanks for your comments. Assuming the performance of my system doesn't deteriorate rapidly with this issue, then I will likely wait until later to deal with this, possibly the second half of March as I have a couple of trips coming up and I'll want to be home to keep an eye on it.

The issue has greatly reduced, I don´t think as a result of anything I did, but it just seemed to get better.

Only theory I can really think of it is it was to do with the hot weather somehow, some component overheating or something. It seemed to get better when the weather cooled a bit. Totally guessing though. Probably isn´t that.

I half expect this issue to recur at some point, however.

I too experiencing the same issue My inverter is Growatt 5000 es 5 kv 

my Panal capacity is only 3.2 kv

Worked last 6 months well 

but noticed PV power fluctuation for the last few days

i will post a pic to see how the OV input is behaving

no error message coming