FoxESS Community - Owners & Installers Forum

I have 12 solar panels (each nominal 440W output).

It has been possible to see a 5kW output on a good day. Over the past couple of days, where the weather in the south-east of the UK has seen temperatures of 32C, the output has never gone above 4kW. Does temperature limit the output, either from the panels themselves or the inverter?

The short answer is yes, your panels will derate for every 1C above 25C the amount depends on the panel and also how it is mounted solaskirt for example increases the temperature as air does not flow as well under the panel.

With the extreme temperates we’ve seen the last few days in the UK, it’s probable you will get between a 10 to 20 % fall in output.

Your inverter will also derate if the internal temperature exceeds (typically greater than) 50C - the inverter provides 2 temperature probes the ‘ambient’ temperature which is not ambient, it’s the internal temperature of the inverter, and also an Inverter Temp which is the temperature of the cooling fans on the rear of the unit.

Depending on your inverter you shouldn’t see any derating taking place unless either of these is 50C or greater in which case the inverter derates it’s power handling to reduce the workload.

Thank you Dave for explaining that for me.

The solar panels are inset into our detached garage roof, with the inverter and batteries inside the garage on the wall.

The internal temperature of the inverter right now is 58.7C, external 53C.

So I just hope the weather cools down a bit for me and the solar panels!

I’ve got a pair of fans sitting on the top of my inverter facing upwards pulling air through the cooling fins, it runs much cooler as a result (10-15C).

It doesn’t need much, one of my friends has a USB fan on top pulling air through and that works well.