Dennis avatar image
Dennis asked

Disable UPS Function with ESS (on EasySolar-II GX)


I'm using a grid-connected EasySolar-II GX 24/3000 with grid meter, solar, SmartLithium battery and setup as ESS configuration (all with latest firmware). Everything in the system works fine, however..

In previous topics I read about humming/buzzing noise coming from the inverter with almost zero loads and connected to the grid. The noise is not so loud, but when I go to sleep at night (and ambient noise is quiet) this buzzing sound starts to get very annoying. It is my understanding that specifically the UPS function ensures constant activity (synchronization) of the transformer with grid and AC-out.

In the system I use the UPS function is not necessary and would therefore like to disable it. However, in VEConfigure (3) the UPS function checkbox is not visible. This may have to do with the ESS configuration (and UPS is enabled by default). Is there a way to disable the UPS function in this ESS configuration?

At the moment I have solved this buzzing 'problem' (I know, it is really just a physical property of the toroidal transformer) by just disconnecting AC-in and I prefer not to do that. Thanks in advance.

Multiplus-IIESSEasySolar All-in-OneVEConfigure 3ups
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1 Answer
Alexandra avatar image
Alexandra answered ·


UPS function is on the grid code tab. But not configurable for every grid code.

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Dennis avatar image Dennis commented ·

Thanks @Alexandra .

Am I correct to state that the buzzing as described earlier (at no load and on-grid) is caused by the UPS function? Is there another way to disable this UPS feature? Or is there any other way to stop this buzzing other than turning off the UPS or disconnecting the AC input?

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Alexandra avatar image Alexandra ♦ Dennis commented ·


So saying buzzing is not super helpful in working out what exactly is happening at the time of the noise.

But a sort of function of ESS is to "test" the grid by frequency shifting. It is sort of related to loss of mains. So under a no load condition this may be the sound you hear is it trying to frequency change and then the induction noise increase in the huge transformer in there. (As you mentioned.)

So really a really the disconnect from mains is the way to stop that. Or a change of LOM detection maybe, but that also is not allowed under some grid codes.

The other things I have noticed that affect the noise is grid impedance and so could also be wiring related as well as the noise can be worse when connected to a generator. Usually people who have generators as well have lower gauge wire connecting it all up.

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