The IP21 rating complicates things. The garage is disconnected and DB is other side of the house too.
It’s actually right next to my office space too, so can hear it clearly. Would probably get used to the hum, especially if it’s in a cupboard, but that fan sounds like a bathroom extractor mounted on a Ricoffee blik.
Bang on. Yes, I hate hearing crap like this. No, I have nothing to do with this part at all, I’m in a completely different area. If this is already raised via community, then the job is done.
As far as I know at least, the transformers have always had some level of potting in order to keep vibration down, but they have always been bolted straight to the case via that bobbin in the middle. Hasn’t been a problem in the past. Not saying you shouldn’t complain… of course complain! Just saying, it might be something else entirely.
I don’t actually think it’s that. As others have said, that’s par for the course. When I move it I’ll add grommets to the bolts in the wall.
The issue is the actual fans, and the resonance they cause, not the transformer.
Edit: Quick & dirty video, bit difficult to record properly. But you can see it’s pushing about 2.5kw to the battery, so expect the fan to be on:
It also helps to understand what PLL means, when reading that change log. PLL is Phase Locked Loop. It’s the bit that syncs with the grid frequency and drives the other electronics in phase. If you get it wrong slightly, then you will hear it.
Even during normal operation, you will also hear a Multi tick and grind sometimes on a weaker grid connection or a generator when large loads disturb the voltage or frequency. But that is not what is happening here, sounds like Marius already has it narrowed down to the fans.
Edit: Come to think of it, sometimes this sort of thing comes down to something stupid like changing your fan supplier, sometimes caused by supply chain issues. Unplanned stuff in other words. I have no inside knowledge here, but it happens. Something that worked fine and never required a damper suddenly does.
Install the “Silent” assistant, which keeps the fan off. Not a fix, but will make it easier to isolate whether it is the fan causing the noise.
If the video didn’t show the inverter, I would of guessed its a sound of a lawn mower 
Best is to check the exact fan model inside and its CFM rating and then compare to the Noctua one (the industrial 24v).
I am not regretting my fan replacement at all. Even at full speed, it is way way more comfortable then the sound in the video.
Just did that, definitely the cooling fans that cause the problem.
The 10kVA model uses 2x different (from the 5kVA and from each other) fans, so that way is more complicated. Also, I absolutely trust the Victron warranty, so I don’t want to mess with it. A Chinesium inverter may only have 1yr, but 5yrs is tough to pass up. I’ll just have to live with it – and they know it.
Separate note: Remote VEConfigure is amazing! Never used it before. My Mk3 is so old it’s a Mk2, so even if you ignore the faffing with cables, just the TX/RX alone is faster with Remote than my physical Mk2 
Another nice thing about the ATS instead of manual override, for changes like this where the inverter restarts you can either just ignore it, or trip the inverter output and set the ATS to manual until you’re done. Nothing notices.
If you know it is the fans, then you can always permanently keep using the Silent assistant and add external fans for the cooling. Just a simple Sonoff TH10/16 with the temp sensor to start the relay/fans above some temp will do it, or a permanent fan.
That way it will not derate your power usage from temps AND you keep your warranty.
A tip: The larger the fan the more air it moves for less speed (rpm) of the fan, which is less noisy. So if you get a much larger external fan running at a slower speed, it should be much more quiet.
I actually already have the MP temperature sensor hooked up to the Cerbo and lying on top of the MP case at the exhaust, so halfway there. Was just for interest sake, but might just bolt it on.
has been open in a tab for 6 months, so this might push me to finally do something with it.
Edit: Oh, don’t even need that, Venus has relay control from temperature built-in. Might just need to cascade the relay depending on fan rating.
Removed the Silent assistant again.
Exhaust temperature climbed to 42 degrees with a temperature pre-alarm and I chickened out 
Did stay pretty quiet.
Had just under 10mins of power outage this morning (work in the street I think) and the MultiPlus carried just over 6kW without the fans coming on. Did switch heaters off once the Whatsapps started coming in, but that is damn impressive.
So kudos for @plonkster and Co then … after ripping him a new one yesterday? 
Sorry, just had to.
Two things can be true at the same time! 
I bought this because it is very very good at what it does, and it is phenomenal value for money. Even more if you take advantage of the ecosystem, which I intend to do with MQTT, Node-Red and so on. More expensive brands don’t let you even see what’s going on, let alone control it without a 10x yearly maintenance contract and so-on.
They should fire the engineer that designed this cooling system
They should hire an engineer with experience designing acoustically appropriate cooling systems.
I dont think there is inverters with acoustically designs in-mind. atleast, not that im aware of.
These things need to be cooled somehow. Hence the majority of the units are installed in a garage/outside.
In fact, I’ve read somewhere that in Australia, these type’s of units (Inverters/batteries/power backups) have to be installed outside your residents because of safety concerns. Remember, yes, lifepo4 is more safer that Lipo, and don’t release gasses like LA batteries, but these is still a fire risk.
Which is why I loved my Goodwe, as it had a massive heatsink at the back, with no fans at all.
that is great!! thought all of them had fans. Thanks, will check it out! transformer based?
Yes, i believe so. Even Plonkster loved them, above the current Sunsynk models
The only reason I went with the larger Sunsynk is due to the Goodwe’s inability to run units in parallel.
My 500va, 800va, the fans run above certain usage.
Same with the 3kva I had, the 5kva I have, the fans run.
Unless you have a fanless inverter, the fans are going to run.
So.the questions are:
Can they be silenced? Maybe to some degree but at what production/more temp derating costs going forward? Is it worth it?
Or can I handle it?
Can the wife handle it?
Or am I told to move it elsewhere?
Personally I want to hear my 5kva. Want to hear the clickity clacking. It shows it works.
And like last night, tried a new thing someone showed me on NodeRED, deployed, and the inverter fans go full blast charging at max. If I did not hear it, I wouldn’t have known for a while.
And the family has learned the sounds coming from the system too.
Now methinks, with all that I just said, 8/10kva, you are going to own moerse fans. Big goeters daai … I may have to reconsider my stance on what I said above, and move the inverter elsewhere. 
Keep in mind that the MultiPlus-II is much worse in this regard than the original MultiPlus or the Phoenix inverters.
Also, the MP-II used to be called the MultiGrid, which was designed for domestic applications, originally only up to 3kVA, with the extra relay(s) and things specifically for grid-code compliance. (They put out an almighty clanking when running through their pre-connection test sequence, but I’m not complaining about that.)
So this isn’t a simple case of “Oh, inverters make noise”.
I remember when I commissioned a Multigrid the first time. It went clacko-clacko-clack… and the RCD tripped immediately. I thought I had broken something. Turns out everything was normal (except the RCD, but that is another story).
I’ve seen a video where someone took the relay test from a 3-phase system (which has even more clicks and clacks) and used it as a sample in an electronic music composition…