FoxESS Community - Owners & Installers Forum

I just installed the fox inverter and batteries at my property in Dec 2025. Under normal operation on sunny days, I have observed that the inverter temperature reaches as high as 93°C, which is far beyond the maximum operating temperature of 60°C specified in the product manual . This is extremely concerning.
Such excessive temperatures raise serious questions about the product quality and system safety. I am particularly worried about the potential safety risks, including equipment failure and the possibility of fire hazards that could endanger the property and occupants.
The inverter is new and installed outdoor with shade on by a qualified electrician. The inverter faces west but there are also trees on its west side and nearly no direct sunlight reaching.
Does these such high inverter temperatures mean a product failure? Should I ask Fox to replace a new one?

Jennifer wrote: ↑Wed Feb 25, 2026 5:35 am Under normal operation on sunny days, I have observed that the inverter temperature reaches as high as 93°C

Sounds like sunlight is directly hitting a temp sensor, try putting some shade cloth or similar material around the battery and/or inverter without restricting air flow too much and if it stops going so high you'll need to find a more perm solution.

Your battery stack will be dumping heat up into the Inverter (it might be installed too close?) and that won't help.
What @evilbunny is saying could be spot on, the temperature sensor could be exposed to the Sun and reading high.

I was looking at the picture and wondering if you can fit a shade that extends over towards tree/fence from just below your gutter.

MaterialBarracuda48 wrote: ↑Wed Feb 25, 2026 10:04 am What @evilbunny is saying could be spot on, the temperature sensor could be exposed to the Sun and reading high.

I experienced this in the past with a personal weather station before I got one with much better shielding for the temp sensor.

evilbunny wrote: ↑Wed Feb 25, 2026 10:10 am I experienced this in the past with a personal weather station before I got one with much better shielding for the temp sensor.

I have a basic tiny one to read the room temperature that sits below my TV, when the Sun hits that, it reads stupid values for sure

MaterialBarracuda48 wrote: ↑Wed Feb 25, 2026 10:13 am I have a basic tiny one to read the room temperature that sits below my TV, when the Sun hits that, it reads stupid values for sure

For indoor temps I got a cheap RPi hooked up to a USB temp sensor that reports back to a LAN server and the sensor is shielded from direct sunlight and the server makes pretty graphs with all the data because the air con only reports accurate temps when it's not actually in use so I needed an alternative source to keep tabs on the air con

Hi guys, thank you all for your kind suggestions. I have no idea where the inverter’s temperature sensor is but will try to shield it more without blocking the good ventilation.
It might need some days to get the results since the rain is coming .

Hi Jennifer,
Would like to know if you have you sorted your problem out. I seem to have a similar problem with inverter temperature on H3 smart 15, going close to 60C, with unit only drawing 7.5kw, which is half the capacity of the unit. Unlike your install, my inverter is mounted in the garage with clearances as specified by Fox.
This is concerning, as the specs for these units state that derating starts at 45C. Hate to think what your unit is derating to at those high temperatures, which are definitely above safe levels for electronics to operate at.

chippa2 wrote: ↑Mon Mar 09, 2026 10:17 pm Hi Jennifer,
Would like to know if you have you sorted your problem out. I seem to have a similar problem with inverter temperature on H3 smart 15, going close to 60C, with unit only drawing 7.5kw, which is half the capacity of the unit. Unlike your install, my inverter is mounted in the garage with clearances as specified by Fox.
This is concerning, as the specs for these units state that derating starts at 45C. Hate to think what your unit is derating to at those high temperatures, which are definitely above safe levels for electronics to operate at.

As it is already shaded, all you can do is force air at the Inverter. As you are in a closed loop, the heat will build up, but it might keep it closer to 45°C or lower with a strong fan.

chippa2 wrote: ↑Mon Mar 09, 2026 10:17 pm Hi Jennifer,
Would like to know if you have you sorted your problem out. I seem to have a similar problem with inverter temperature on H3 smart 15, going close to 60C, with unit only drawing 7.5kw, which is half the capacity of the unit. Unlike your install, my inverter is mounted in the garage with clearances as specified by Fox.
This is concerning, as the specs for these units state that derating starts at 45C. Hate to think what your unit is derating to at those high temperatures, which are definitely above safe levels for electronics to operate at.

Hi,
My installation company said they contacted Fox technician and were told the inverter could still work even the temperature is as high as 90c.
I don’t know whether my inverter’s temperature sensor is working properly or not, since it looks like the pv production isn’t affected. I could see as long as the inverter works with high capacity, the temperature is always above 60c.

Jennifer wrote: ↑Tue Mar 10, 2026 8:18 pm My installation company said they contacted Fox technician and were told the inverter could still work even the temperature is as high as 90c.

According to a research paper on LFP degradation, when the battery temp is 45C and the SoC is high the capacity will fade 4x faster than 25C.

Jennifer wrote: ↑Tue Mar 10, 2026 8:18 pm I don’t know whether my inverter’s temperature sensor is working properly or not, since it looks like the pv production isn’t affected. I could see as long as the inverter works with high capacity, the temperature is always above 60c.

AFAIK there is more than 1 sensor, so my guess is it uses readings from more than just that sensor before deciding to shut itself down.

Early days with these inverters. will have to keep a close eye to see how they perform. Other users have installed computer fans on top and also on the bottom to get more air flow and that seems to lower the operating temperatures, even if its a small amount it all helps. The reassuring thing is that Fox indicate that the units will operate up to 90C.

The picture shows that the rain protection is made of glass. I recommend that you at least paint the glass white. This way the light will be reflected and the temperature will be lower. Additional ventilation is ok and also not good because additional ventilation brings dust.

fumbo wrote: ↑Thu Mar 12, 2026 4:04 pm The picture shows that the rain protection is made of glass. I recommend that you at least paint the glass white. This way the light will be reflected and the temperature will be lower. Additional ventilation is ok and also not good because additional ventilation brings dust.

For far infrared light (heat) white surfaces still absorb some heat, useless it's the ultra white kind or a special coating.

So ideally you need to have the enclosure made from something like wood that can absorb heat because glass will reradiate heat.