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jbakuwel avatar image
jbakuwel asked

Flickering lights in off grid with SMA PV inverters

Hi,

I have two customers complaining about flickering lights at certain times. I found this rather non-verbose :-) reference "Fronius has a special firmware available, on request, that fixes light flickering issues that occur on certain installations under certain circumstance".

One customer also has a DC coupled SmartSolar charge controller; the other one does not yet have that.

These customers have SMA PV inverters, not Fronius PV inverters. Does anyone know which "certain" installations and "certain" circumstances are referred to here so I can discuss it in sufficient detail with SMA?

Jan


MultiPlus Quattro Inverter Charger
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2 Answers
mblowes avatar image
mblowes answered ·

Could it be water pumps cycling?


I've just done an offgrid.. it happened to be 3 phase.. I was moving some load between circuits and lights started to flicker intermittently afterward.. Turns out I moved the fresh water pump to same phase as lights. Moved it to 3rd phase and problem solved.

Multi's could start pump no problem.. but there was this little flicker.. Not sure if there are other ways it could be solve... Pump is just a small 1hp 230V AC induction type.. driven from 2 Multi 3kVA in parallel on that phase.


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jbakuwel avatar image jbakuwel commented ·

Hi mblowes,

It's surely not pumps starting. I think it's quite normal to see a minor flicker once when a substantial load turns on.... here in NZ we even observe that in grid connected houses.


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Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

I had a little experience with this before and after it was resolved by the Fronius firmware fix.

It generally occurred during the threshold periods between production and non-production, or charging and not-charging.

For example, at the start and end of the day when the inverter was right on the edge of it's available voltage window, but still had very little power production.

Also when the battery was full and the PV inverter needed to ramp down to nothing, then slightly back up again, and then the Multi would switch from charging, to discharging and then back again.

Whatever was happening would only effect some appliances (mainly some brands of LED lights) and some installations (household wiring?). Whatever those details were, as far as my experience everything was resolved with the Fronius firmware update.

Taking my Victron hat off, I am only hypothesising now, (risky) but my anecdotal observations were that the Fronius added some small (seconds) additional delay between the conditions being right to start-up, and beginning actual production, to prevent the hysteresis condition.

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jbakuwel avatar image jbakuwel commented ·

Hi Guy,

Thanks for getting back to me. I haven't been able to get 100% clarity about the circumstances when this is happening but it surely is happening when the batteries are full (and the PV inverters are ramped down). The Multi is making a "repetitive humming sound" (as if it's asked to supply power, then stop, then start, then stop) with a frequency of a couple of Hz. The lights flicker with a higher frequency and the flickering of LED lights is quite a problem (headache material).


May I ask how Fronius was "prompted" to create this firmware that is only available on request? It would be great if SMA could be prompted in the same way (but I'm not holding my breath). Or ... would it be possible to get a bit more detail about this fix so I can see if one of the many Sunny Boy parameters might help?


Perhaps relevant is that - as far as I know - this does not happening with the combination Sunny Island (battery inverter) and Sunny Boy (PV inverter). We have one customer with that combination and there are no complaints.

thanks,

Jan


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Guy Stewart (Victron Community Manager) avatar image Guy Stewart (Victron Community Manager) ♦♦ jbakuwel commented ·

This all occurred before I worked for Victron.
The fix was available as a limited test by request only. It does not effect all systems.
I had a many systems working without issues, and then one that did. Installing the firmware fixed this issue.

After some months, the fix was included in the normal Fronius firmware, and now the issue is resolved.

I have heard there has been some similar experience with Enphase, but I only know of that second hand, without any issues myself. Enphase firmware is updated remotely by Enphase, so its a little less clear what (if anything) happened there.

I assume the fix came about from sufficient complaints to both Victron and Fronius, an engineer would have been assigned to investigate, and found something that could be done.

This community is a good place to discuss it, but issues like this also MUST be communicated to your equipment suppliers.

This may all take some time, so I would also strongly consider replacing the most offensive lights with another model or brand that is not affected.

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jbakuwel avatar image jbakuwel Guy Stewart (Victron Community Manager) ♦♦ commented ·

Hi Guy,

So far it affects all customers here with a SMA SB and Victron Multi combination. I can test to see if an LED light that's offending when powered by a Multi works fine when that exact same LED lights is powered by a Sunny Island. Would you be able to suggest how we should proceed from here? I'm happy to report it to SMA but it might be better if Victron would talk to SMA?

For one customer we're researching if we can use DC powered lights instead but of course it should be possible to power lights with a Multi without these effects too.

Unfortunately it is not always possible to replace the offending lights; in the cases here all LED lights we have tried so far of different brands and different types are offending. Also LEDs in appliances (e.g. fridge) are affected.

Jan

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Guy Stewart (Victron Community Manager) avatar image Guy Stewart (Victron Community Manager) ♦♦ jbakuwel commented ·

http://professional.victronenergy.com/support/ would probably be the best channel to make something official with Victron.

Do you have contact with other installers who install a SunnyBoy and Victron combo? Are they seeing the same issue? Get them to report it via that link as well. Systemic issues that are being reported that effect everyone (with that configuration) will get more attention than isolated issues.

There must be thousands of off grid Victron systems with SunnyBoy inverters on them, so I am surprised to hear that it is a 100% reproducible issue for you, and yet not see many other similar posts (one other here I remember).

Victron approaching SMA would only be useful if we could also come with a long list of case reports (and ideally VRM connections) that show SMA equipment. And even then, I would think that if it was their own customers, distributors and support receiving the requests, it would help (though likely to get some 'buy a Sunny Island' recommendations, that same as Victron might recommend buy a Victron MPPT to resolve).

It must be quite severe to affect all lights. I have had some flickering LEDs on my grid connected house before, but only some brands and sizes, which seem to be more sensitive. Perhaps look at ones that are dimmer compatible, they might offer something extra in their smoothing electronics. I know that isn't a perfect solution, but it's something to do while also encouraging competing manufacturers to work together.

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jbakuwel avatar image jbakuwel Guy Stewart (Victron Community Manager) ♦♦ commented ·

Hi Guy,

Thanks for your help so far. I'll continue this thread on http://professional.victronenergy.com/support.

There are a lot of parameters that control the behaviour of SunnyBoy inverters but unfortunately SMA has not provided accompanying documentation so it will be a matter of trial and error. I'll give that a shot as soon as I have a bit of time, meanwhile we are going to power the lights for this customer with DC. When the batteries are full the flickering lights are indeed headache material; we can't obviously supply power systems with that behaviour to our clients.

We supply all AC coupled off grid systems with a DC coupled Victron MPPT controller (for obvious reasons) but these systems also need AC coupled inverter(s).

The LEDs are dimmable and when dimmed still flicker. I've observed the flickering albeit to a much lesser extend also when the batteries are not full, so that is interesting.

kind regards,
Jan

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Andrew Ayles avatar image Andrew Ayles Guy Stewart (Victron Community Manager) ♦♦ commented ·
I also have a 5kva multiplus ac coupled to a SMA SB5000TL21. While the ac coupling works perfect the flickering at each end of the day not only affects the led lights but also the old incandescant globes that I still have a few of. It definatley occurs when pv power is low and roughly matches the loads present at the time. I'm lucky in that this is my own installation and not one of my customers. I am curious if one of the million sma settings within sunny explorer could provide a simple fix for this problem as apart from this the victron sma combination actually seems to work amazingly well.
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jbakuwel avatar image jbakuwel Andrew Ayles commented ·
Hi Andrew,


The lights are still flickering but it's temporary as the lights will ultimately be DC powered. Not really a solution, but I find it hard to justify investing a not insignificant amount of time without knowing what the chance of a solution might be. This post suggests the cause of the flicking is likely to be found in the AC coupled PV inverter, not in the Victron equipment as a Fronius firmware update resolved the issue in the past. Clearly the presence of an AC coupled PV inverter (Fronius or SMA, maybe others too) is required for the flickering to happen: we know that much.

Initially I thought flickering might happen at the end of the day when the batteries are full and the PV inverters are derated. But I'm starting to think that it happens when the PV power (from the AC coupled PV inverter) roughly matches the loads as you say, no matter the SoC of the batteries nor the frequency generated by the Multi for that matter (ie. whether the PV inverters are derated doesn't seem to matter).

I've had a number of conversations with 2nd and 3rd level support at SMA. I asked for documentation of all those parameters (to diagnose another issue) but all I got is a list with a marginally longer description of the parameters that doesn't add much to the name of the parameter, ie. not very helpful.

I think the only way to figure this out is trial and error.

Happy to help think and maybe - in time - try a few settings but don't have much time otherwise. Still it would be nice to see this issue resolved of course.

Jan



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Oliver avatar image Oliver jbakuwel commented ·
Dear Jan,

I have read your posting with great interest and since one year has past since your last post on this I wonder if you have found a solution? In the past I experienced a similar flickering issue with Fronius. This consumed an extreme amount of time (finally solved with an unofficial firmware) and since then I only offer SMA for AC-coupling. However in my last off grid installation (SB5000 + 2xMPII5000 parallel) I also get this strong flickering (only) on dimmable LED lights whenever the condition SB production equals house consumption is met.

If you have an update on this that would be highly appreciated.

Best regards Oliver

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jbakuwel avatar image jbakuwel Oliver commented ·

Hi @Oliver

Unfortunately I haven't found a solution yet. I have noticed flickering lights with a MP-II 3KW in a system without a PV inverter (just one 100/20) though.

CC @Guy Stewart (Victron Community Manager)

This all Victron system (MP-II 3KW with MPPT 100/20) is an experimental system (not used for production). The flickering in this system is not as problematic as the flickering referred to in this post but is still noticeable and present most of the time, so perhaps a good system to dig into?

Jan


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thanar avatar image thanar jbakuwel commented ·
any chance the BMS is cutting-out the battery due to cell over-voltage?
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jbakuwel avatar image jbakuwel thanar commented ·
Hi @thanar


If that would be the case then the whole system would power down and the lights would be off :-)

Jan

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thanar avatar image thanar jbakuwel commented ·
No, the system wouldn’t shut down; the DC bus (inverter input, charge controllers) would keep the system alive
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jbakuwel avatar image jbakuwel Guy Stewart (Victron Community Manager) ♦♦ commented ·

I don't know if it is relevant here but am noting that I haven't observed the Multi going into Float charging (ever); it stays in Absorption while the DC coupled Smart Solar charge controller is in Float charging. The Multi has slightly lower voltages (as recommended by Margreet when I met here in Auckland a while ago), so I would actually expect it to switch to Float charging before the Smart Solar does, but it ain't so.

Multi: Absorp = 55.0V, Float = 53.7V

SmartSolar: Absorp = 55.2V, Float = 53.9V


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Keith Arnold avatar image Keith Arnold jbakuwel commented ·

interesting because i have not had light flicker but i updated firmware of Fronius just the other day. now i have flicker. multiplus with mppt and fronius. grid fail. low load.equals flocker. maybe the latest version has gone backwards...

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Frank avatar image Frank Keith Arnold commented ·
Are you still having light flicker ? as im having this problem now
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