I have two PIPs in parallel so 8kVa and only get to 50% load I designed the system to run at no more than 50% normally 20% to 30%
but even at low load the temperatures can go to 50c
I have 8% load now air temp is 28c the PIP temp is 36c
I do not like running heatsinks at temperatures higher than I can touch them
when the heatsink gets to 50c the semiconductor could be approaching over 150c
the lower the junction temperature the longer they last
The capacitors are close to the heatsinks and are heated by them they suffer most from the heat
Here in Sydney the temperature can get to over 40c (41c recently)
the heatsinks in a PIP would be above 50c under those conditions
I thought about placing a copper bar between the fets and heatsink but this involves to much work
I have used this method in my own power projects and it has made a huge difference to the ouput devices temperature
reducing them as much as 10 to 15 deg c