Something to remember is that PV panels are sold as a peak power rate, but that is not what you normally get. All panels are like that.
As an example lets look at the ArtSolar 550W panel
The STC values is that wattage it is sold under and is measures in perfect factory conditions. It is used so you can compare vs the next panel and most manufacturers will use very similar test conditions, but this could be a bit different. Check the specs.
The NOCT is more the normal power you can expect every day use when the PV is mounted in the sun, hot and hopefully not to dusty.
So what to do with this information?
For safety calculations (wire thinkness, fuses, breakers, max voltage limits) you should use the STC values.
For usage requirements (how much panels you need to power your system) you should use the NOCT values.
I also have lost of shade in the winter that is out of my control. So I looked at half cell panels (144 half cells) and instead of using one bit MPPT with one or perhaps 2 trackers I went with smaller MPPT charge controllers each with their own tracker. Victron’s modular system makes this easy to do, but if you are looking at another system where the charge controllers are built into the inverter you might not have that opion.