I’d like to find a solution for the humming noise from my MultiPlus 2 GX. I have several solar-panel inverters, and they’re completely silent. The fans are also very noticeable—is there an alternative for them?
Transformers hum, that is what they are designed to do. Your PV inverters will not be transformer-based, so like Victron’s RS product range, won’t hum.
There are a lot of topics on fan modifications and ways to help insulate the inverter while mounting which reduces resonance. Have a dig around with our search feature and you should find some pointers.
There’s no solution for this, except perhaps when mounting it on the wall, use a rubber sound-dampening mat and rubber plugs; that makes quite a difference.
There are various modifications for the fan, including replacing it with a quieter version or mounting it in rubber as well.
You’ll have to search through the community for this. It definitely won’t be quiet, though.
This has helped me; I’m going to do this, but wouldn’t it be possible to isolate the toroidal transformer itself by mounting it on rubber? Has anyone already tried this?
I’ve tried that in the past as well, by decoupling the transformer from the enclosure, but it doesn’t help much
it’s also very difficult given the weight, and the transformer needs the enclosure for cooling as well
if at all possible, the best option is to install it somewhere out of the way and decouple it using a rubber sound-damping mat
mine are mounted in a separate room on sound-damping rubber, so I can’t hear anything, even at full power
Or, buy an RS instead.
Which vibration dampers did you use to mount the MultiPlus 2?
Additionally, replace the MP2 housing with an aluminum one, if you think it’s worth it.
You can check to see if this will improve the situation by removing the cover while under load.
If the sound is much lower, then aluminum can help.
Hello,
you can simply use soundproofing plugs from the usual suppliers, Fischer/Würth/Tox, etc. I used only rings made from
construction protection matting myself; they help too, but not very much. It might also help to put some rubber matting on the housing,
as that absorbs some of the vibrations. There are also suggestions here for other fans with better airflow
characteristics and better electronic control—just use the search function.
Have you tested this solution (pictures)
Not with MP2 hardware, with an APC UPS that uses the same topology and hardware principle according with US Patent US5302858A.
Which model MP2GX do you have? I initially had an MP2GX 48/3000 which made a horrific noise, not just hum or fan noise but a whistling noise which could be heard throughout a 3-storey house. I upgraded to an MP2GX 48/6k5 and there’s a bit of hum and fan noise, but nothing outside the garage where it is installed.
So I believe there is a design flaw in the 3000 model which may be something to do with how the transformer has been wound, but I’m guessing here!
I have a MP2GX 48/3000.
Indeed, they are noisy…
Hum alright, but HF noise not so much…
Usually, in series with the primary there is an inductor on ferite, used for filtering PWM pulses, reducing ripple current and reducing idle loses.
That inductor is usually making that whistling noise, but it’s not uncommon for the big transformer to do it also, because that big transformer is made to work on 50-60Hz and its core has massive loses (through Foucault and hysteresis) when it’s subjected to tens of kilohertz used for PWM.
Oh wow, thanks! That is really interesting to know!
I see here a possibility for active Noise Cancellation, just a loudspeaker and a microphone inside the cabinet.
There is a guaranteed, foolproof way to stop a transformer hum.
Turn it off 
Hello, I had a similar problem. After isolating my Multi 48/3000 with soundproofing plugs and rubber pads, about 30% of the noise was gone. Then you could only hear the fan. Because of the PWM signal, it produced strange humming noises that really got on my wife’s and my nerves. I discovered that the exhaust air ducting hadn’t been designed optimally: the transformer at the top and on the left reached around 50–65°C under heavier loads, so the fan would sometimes ramp up and down. As a first solution, I fitted three small, speed-controlled fans underneath, blowing additional air into the enclosure. Hardly any improvement. Then I hung a 120 mm fan directly in front of the transformer and had it blow air onto it. Finally, I fitted an 8 cm perforated plate and spaced the front of the enclosure away from the electronics and the transformer. What can I say? Problem solved. Happy wife, happy life!!!
Now I’m going to attach a temperature sensor to the hottest part of the transformer with thermal adhesive and control the whole thing with a Shelly + Add-on. I can tinker with it until the cows come home!
Exactly what I’ve been saying…
Either remove the front casing, or in your case find a position where the magnetic fields doesn’t interact so much with the casing, or fit an aluminum casing.
The difference in price for a case of this size is about 50% more. So instead of a housing cost of 10USD, it would be 15USD…
I’m sure the end user will be happy to pay the 5USD difference for a quieter inverter. Not to mention the heat dissipation and weight…