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.
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!
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.
It doesn’t need much, one of my friends has a USB fan on top pulling air through and that works well.
I was puzzled about what Ambient Temp (ambtemp) was measuring and was about to ask on here but this thread seems to answer my question. My ambtemp readings haven't dropped below 40C, day or night, since installation just over a week ago, and have peaked at around 60C during this hot spell. I was wondering if I needed to address this but the inverter (H1-6.0-E-G2-WL) does seem to be operating just fine and I'm getting expected loads. Seems like these things just like to run hot?
Attachments:
My Amb Temp (or inner temp as it should be labelled) tends to be low 40's to early 50C in this weather, but i've got fans that kick in to help out.paulshields wrote: ↑Thu Jul 09, 2026 1:45 pm My ambtemp readings haven't dropped below 40C, day or night, since installation just over a week ago, and have peaked at around 60C during this hot spell. I was wondering if I needed to address this but the inverter (H1-6.0-E-G2-WL) does seem to be operating just fine and I'm getting expected loads. Seems like these things just like to run hot?
They do run hot, 60C is getting up there and the inverter will be starting to derate at that point (to self moderate) - in this heat your panels will be derating as well, if you see any significant loss of production a small fan above pulling air over the cooling fans on the back will help but also to be fair this is about as hot as it gets for the UK so you are seeing the worst
Cheers Dave. Yes I agree that ambient label is confusing 
. It's almost like it must be sitting on top of the CPU or something.
Well so far at least the system seems to be working pretty much as I expected even in this mini heat wave. I've 18 x 480W panels and seeing PV maintaining 7 to 8 kW, and it's staying reliably up there at peak times of the day so no derating currently it seems.
I'm definitely going to look into a fan. Just need to get some power into my "plant room" (basically a brick lean-to on side of the house).
. It's almost like it must be sitting on top of the CPU or something.Well so far at least the system seems to be working pretty much as I expected even in this mini heat wave. I've 18 x 480W panels and seeing PV maintaining 7 to 8 kW, and it's staying reliably up there at peak times of the day so no derating currently it seems.
I'm definitely going to look into a fan. Just need to get some power into my "plant room" (basically a brick lean-to on side of the house).