You mention the P182 but what about people such as rpsgc interested with a Solo?
The standard hot box testing result applies. Nothing special about PSU cooling in the Solo.
It's simple enough to summarize:
1) Keep the immediate temperature around the PSU to under 25C and the fan won't start up till >300W. When/if it does, it will still be about as quiet as any PSU you can buy.
2) The higher the immediate temp around the PSU, the lower the load point at which the fan will start up. It's directly tied to temperature.
Yeah... from thermal point of view Solo and every PSU on top case is hot box for PSU with that heater also known as CPU immediately under it.
Now this fanless operation of PSU at low internal temperatures actually rises one question considering dual chamber case design: One of its goals is to cool HDDs in lower chamber by slight airflow created by PSUs fan for minimizing number of necessary fans so what kind effect PSU's fan stopping has to their temperatures.
Of course HDDs won't generate that much heat but acoustically good soft mounting prevents cooling by conduction to metal structure of case and when you start adding HDDs close to each others their heat will fast add up if there's no airflow.
At least in Sonata effect to HDD temps is very noticeable when side is opened and airflow past HDDs stops.
Do you use a simulated sine wave UPS? If you do, you may certainly buy the Seasonic and let us know.
With that good electric and acoustic performance I'll probably get this new Seasonic after price settles but my APC Back-UPS Pro 650 got replaced by MGE Pulsar Evolution 1500 and only square wave (nothing sine wave in them) UPS I can get my hands on is low power one from time when graphics cards didn't need any extra power cables or motherboards separate power cables for CPU.
I do know CyberPower and APC both say there can be issues with an active PFC unit, and CyberPower added high efficiency active PFC as another concern. Why don't you call them and ask? After all, they do represent the company making UPS and no need for them to talk you out of buying their unit.
You forgot that in your country they need to legally cover their rear to not be sued from god knows what.