Don’t know about the Multi II’s, but the 3kw Multiplus’ fans are also quite noticeable with loads over 1kW.
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I have a friend down in Stellenbosch, he had a Sunsynk installed a few weeks back, high pitch noise on the son’s Pc is so bad that the son refuses to use it. Same noise on TV.
A member from another forum, also from Capetown, phoned me a while back with the same issue. Wanted advice but I could not really help him.
Heard of at least 2 other similar complaints.
Guess there should be some logical explanation for it…
Harmonics of some kind… which would point to a poor THD figure. Would love to get a scope on that…
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OK, perhaps I can throw a bit more info on this fire.
So the sunsynk is as far as I can determine an HF design. For @karischoonbee 's sake, a quick refresher on the difference between HF and LF designs (high frequency vs low frequency).
An LF design takes 48VDC and turns it into 48VAC (peak) at 50Hz, and then feeds it into a (usually bulky) transformer to turn that into 230VAC (RMS).
An HF design takes 48VDC and turns it into 325VDC (usually a bit more) using a boost converter. Then it turns the 325VDC into 230VAC (RMS) using another stage.
A boost converter is essentially a transformer with some DC->AC->DC conversion thrown in. The trick is that you can use a higher frequency than 50Hz (typically 50Khz to 150Khz or thereabouts), so that makes the transformer much much smaller.
These inverters are then sometimes called “transformerless”. Which is nonsense… the transformer is still there, just smaller. I digress.
Humans cannot hear frequencies above 20Khz or so. Children can hear some of them. As we age we hear less of them. So in general we should not be able to hear the hum of that HF boost stage… but…
In DC/DC converters there are all sorts of stuff going on, they speak of running in continuous mode or discontinuous mode, and of course a lot of development goes into making things more efficient. Without going into that into too much detail (since this is about as much as I know anyway!), newer DC/DC converters to something called cycle skipping. And this you can actually hear…
I have a cell phone charger, for example, that is silent while the phone is plugged in, but makes a high pitched whine the moment I unplug the phone (and therefore remove the load).
So this is my guess. Some kind of anomaly in the boost stage causes an HF ripple around the 20Khz mark, and some people can hear it…
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@plonkster , my colleague has the same 5 kW Sunsynk, he cannot hear anything from my inverter, but he can definitely hear the high frequency noise emanating from his inverter.
Any explanation for that
Sorry not really 
Meaning you would love to speculate, but speculation is dangerous? 
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I would suggest that even though both are built to the same design spec, there are different components in each. (seeing as one thing cannot occupy two locations at the same time - time travel excluded 
)
Both the equipment and the components inside those equipment have to be inside a tolerance to pass QC (Quality Control) and there is the difference.
Both inverters have the same type of, let say, capacitor in the circuit, but the one of closer to the edge of the tolerance than the other.
Both work in the design. With one you just get the extra humming for free 
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Try a firmware upgrade? This sort of noise can typically be addressed in firmware (add a spreading algorithm to the switching regulator control algorithm). If you hear it on one unit but not another, it could be the firmware version.
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Thanks, will suggest the firmware upgrade to my colleague
I would challenge the Accessibility statement made in the first paragraph if you are a DIY’er. One of the big selling point being pushed by Victron is that it’s a DIY’ers paradise in that you can pick components, mix-and-match, write your own integrations, use modbus and just go crazy - like we all like to do, and things just work.
The problem is when you run into an issue then there is no support for you if the dealer you bought the kit from cannot solve your issue (I know, I am at that point). All the other points @TheTerribleTriplet mentioned I fully agree with.
PS. Wanted to add that I am interested to know about the Synsynk support here.
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That is what the community is for, or this forum, or you can even phone me, I will try and assist where ever I can.
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Thanks @JacoDeJongh I appreciate it and will take you up on your offer sometime next week. I have an installer here this week to extend my solar a bit and should be finished by next week. I will however give him the chance to attempt a fix before I call you.
Pray tell the issue you have?
Ok, you asked… I’ll start a new thread as not to cloud the current thread with irrelevant information.
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In the ideal word there is three levels of support.
- The installer. This guy should ideally have a modicum of training. People who hire an installer should hire one with some training. Ideally.
- If the installer cannot fix it, then it goes up the chain to the reseller. If they cannot fix it, …
- It goes to level3 support. At this point, someone from R & D contacts you and tries to resolve it.
That’s in a perfect world. There are other ways to get into the chain. One way is to mention the issue on the community site. There are at least two guys around who reads posts on that forum, and ones that seem particularly worth of attention is passed onto someone more technical.
With all that said, sometimes it might take a while to address a problem. For example, a problem that involves a relay assistant issue that is rather very specific to your site… may be given a lower priority than a problem that affects multiple sites. Level3 is also the most expensive kind of support, because it literally pulls a developer of a task he is working on to fix something else. For some of those tasks, there may be only two people who can look into it… for others there might be 10.
So as always… there are so many factors that go into this. You want to help everyone… you cannot always do that.
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Just saw this post. When we got our quotes. The Victron was hard to understand. We needed this and that, and it does not have… >>>> You have these models etc etc. it was all too confusing for a laymen. Then we wanted to buy two. My quote alone topped 70k to match the 8kw sunsynk, My sunsynk . 30k, and it was so understandable. I have zero knowledge on the Victron so would not even be able to answer basic questions or knock it in anyway. But the Sunsynk has lots and lots of documentation, escpecially from the CEO Kieth.A CEO contributes to the product and he is reachable, its also match to a American version, and boy can they do YouTube. Its like a solar course on its own. The 8kw does not have the noise problem. The 5kw has since been corrected with the later firmware I read. I read a lot … Bottom line. Simplicity and cost made my choice. The features really work and hopefully save me money. Its a Hybrid fully from purchase. Has a simple graphic configuration and monitor LCD screen. Works with most BMS batteries, supported. When read how the TTT plays with his battery, I would not even attempt to connect a battery so complex and even attempt to make it work. I will burnout the first week…
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Victron is actually very straightforward once you understand how these systems work. I found that installers that do not actually know the product well makes it sound super complicated but it really isn’t.
The most commonly seen solution is the inverter coupled with an MPPT and a GX device. The inverter does mainly just the inverting (AC to DC, DC to AC). The MPPT charges your batteries from the solar panels. The GX device is like the brains controlling it all (but the system can operate without the GX given proper settings, as per my understanding).
To compare an 8kW Sunsynk to a Victron system is maybe a bit difficult, because then you go into Victron’s more hardcore products (Quattro), but comparing to the 5kW Sunsynk is easier. Still, the Victron system will definitely be more expensive than the Sunsynk, and you alone can decide whether the reasons for it being more expensive are things you value. That is just the reality of it - a Victron solution is objectively a superior solution in most (probably all) areas except for cost.
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Love your answer. Thats objective and helpful. Thank you
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Strengths of the sunsynk deye
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Pretty easy to install even for someone with no experience installing inverters, like myself. Configuration is also very simple. Just a couple intuitive screens and you done.
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price when compared to most other hybrid inverters, not just victron. I originally was undecided between the victron and goodwe and was watching lots of videos of both. Then I watched a video about the sunsynk interface and I was sold.
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high voltage mppt means cabling is a lot more simpler
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ac coupled for generator, microinverter or smart load. I used the microinverter and although it wasn’t as straightforward, I managed to hack it with node red to get it to work as expected.
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time of use settings make setting up an ess very easy by configuring the battery soc at various times of the day
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modbus integration. Although this isn’t for the everyday joe, real time monitoring is possible and also changing inverter inverter settings. I had a problem where the inverter would not turn off the microinverter when batteries were full and I would feedback to the grid. So I just wrote a node red automation, with the help of the other forum member, to enable the MI zero export field when my battery got to 95% and disabled it when battery was lower than 90. Problem with the field enabled always, inverter would just randomly cut power from the microinverter.
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Battery comms is supported with most of the locally available batteries.
-parallel configuration is pretty straightforward and easy to setup
-Improvements do come often like the firmware upgrade that resolved the issue with the mppt current limitation.
Weak points
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change/version control is non existent. When you get an update, no one really knows what’s nee and what’s broken. Few weeks ago when I was trying to setup the parallel, I couldn’t configure the modbus sn on the new inverter. After sending it in to support, they figured it was latest GUI software that was the problem. After going back to the older software, all was good.
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sometimes oversees support don’t really know what they are talking about. I was told I can’t parallel my old inverter with the new one as the old one didnt have an eol resister switch. Thankfully they were wrong.
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they are still relatively new in the market and although support as improved drastically from when I first installed it, the language barrier does pose a problem at times.
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they keep changing the requirements for approved installers when I first installed mine there was no such approved installed. When they initially started there installer approval, one needed 5 installations to become approve. That has since changed to 10.
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Real time monitoring and configuration. Although this is changing with their soon to be released dongles, they did enable the remote config through the existing solarman app some time ago only to take it away after a short time. I’m busy setting up my home assistant integrations so this isn’t really a problem for me.
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