question

tobyfw avatar image
tobyfw asked

Loud hum when mains connected - configuration issue?

Dear community,

we are currently trying to reduce the noise level of our Quattro-II 5000, as it is located close to our living area, and producing a more-or-less constant and loud 50Hz hum (the fan is less of a problem). We will install soundproofing mats and dowels, as has been recommended on this forum.

By coincidence, I just met solar professionals, who told me, that the noise is likely the result of a configuration problem. I am doubtful of that, as the hum was there from day one - also, posts on this forum seem to suggest that the humming is pretty normal for this device. But still - are there settings in VE.Config or the Cerbo GX, that could lead to a reduction of the humming?

In fact, sometimes the humming disappears for a half a minute or longer, so generally it is possible for the device to work silently - then again gets louder gradually.

When I switch off mains, and run on batteries, the noise level is much lower, almost silent.

Loads on the other hand do not seem to make a difference - the humming is there even when all loads are disconnected, it is also there when idle (not charging or charger switch off in VE.Config).

One thought was that it could be due to a low quality of the AC IN (we are based in Ukraine, so who knows), but settings such as Weak AC On, PowerAssist Off, UPS Off did not have an effect on the noise.

Otherwise, the Quattro-II is controlled by the Pylontech BMS (state "External control", the Quattro-II mostly lights BULK or ABSORPTION, but according to the chart it sits idly on "External control", battery at 100%, not charging).

Thank you for suggestions

Multiplus-IIcerbo gxVEConfigure 3
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2 Answers
nickdb avatar image
nickdb answered ·

It is a large transformer it will hum. The inverter has to be synchronised to the grid, this will make it hum louder at times and softer at others, which is why it is much quieter with no grid. It is an inherent feature of a transformer-based system, that is amplified by the case design.

High frequency, transformerless systems, like the RS models behave differently.

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Michelle Konzack avatar image
Michelle Konzack answered ·

Right it is the large Transformator and I just discovered, if it is warm outside, e.g. +2°C and more, the the humming goes away.


If I hace MINUS temperatures than it come back, and disappear again, if my MultiPlus-II 24/5000 heat up under a load of more then 2kW.


However, in warm weather I can not hear any thing.

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