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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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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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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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