FoxESS Community - Owners & Installers Forum

Hi. Newbie here. Hoping someone can please help me?

Had our system installed last week. The inverter gets noisy and extremely hot to the touch? Has anyone else experienced this?

Everything was working great until the first fully sunny day. At peak production the inverter got extremely hot and started making a loud humming noise - sounds like an internal fan going into overdrive. You can imagine how shocked we were!

Our installer is coming back in a couple of days to double check over the install but they have suggested that it is common for Fox inverters to become hot and noisy when working at capacity. I won’t accept this.

We haven’t yet contacted Fox support but obviously will do this if the installer can’t find any physical issues.

Here’s a pic with the details of our inverter model. It is sited in a garage so well sheltered from direct sun.
Is the firmware out of date? Will updating that sort the issue?

Any inverter (not just Fox) when working hard will produce heat, it's a by product in the energy exchange, the whole back of the inverter is a heat exchanger designed to get rid of that heat and it's not that unusual on a very sunny day for the inverter fins to be at 40C or 50C.

Is the Inverter mounted indoors ?, normally they would be mounted in a garage, roof space or outside where there is plenty of air circulation to take the heat away.

I can't comment on the noise other than to say inverters do make squeeks, pops and buzzing noises when working - they are not normally that intrusive when compared to normal ambient noises but if it's mounted in your kitchen or somewhere like that it could be irritating - i'm not aware of any inverter that runs totally silently.

As Dave has said .. they get hot when generating ... I have added a few fans on top, pulling the heat away from the unit. I actually have these connected to a "smart" plug .... and Home Assistant to automate so they come on when temp reaches a certain limit. You can see on my graph, where the fan has kicked in

It's surprising just how effective a couple of computer fans is at reducing the heat.

I got a pair of 140mm computer fans on USB, the total power draw is only 4W on high, but it drops the inverter temp down to below 40c even in this heat. KH7. Have to say that I have never noticed it making any noise, however. Quite a bit more effective than the 50W pedestal fan which I programmed to go off at 45c. It hasn't turned on ever since I added the computer fans, but when it did turn on, it doesn't reduce the temps as much as the computer fans.

Keeping the temp low is good - they derate if it gets too hot, and the components should last better. Personally I didn't put that one on a smart plug, on the basis that it's only 4W. Also thermal cycling can be an issue for some electronics.

WyndStryke wrote: ↑Sat Jun 21, 2025 11:47 pm I got a pair of 140mm computer fans on USB, the total power draw is only 4W on high ...

Are you using the USB connector on the inverter itself to power the fans?

No, I think that USB connector is for firmware updates and similar. It's using wall power.