HY 3.6 Gen3 and 9 panels giving approx 4kw max. All the panels are on the same roof and facing the same direction and currently it's configured with 5 panels are on one string input and 4 on the other. The question is whether they would be better configured all on one input string? At this time of year when there is very poor solar, is there an advantage to having a higher string voltage?
I think it is more a case of any panel on the string that is possibly shaded limits the whole output of the string.
If they are all same elevation and nothing that might obscure any of them, than they could all be on the same string without issue.
I am no expert on this, and I think you would need to see what panels you have and any limitations on your kit
https://solarenergyconcepts.co.uk/post/connecting-solar-panels/#:~:text=Connecting%20multiple%20solar%20panels%20is,current%20that%20many%20inverters%20need.
Beebod I have an identical setup (in terms of PV panels) and provided you have the startup voltage set to 120V then there's no issue about splitting strings.
It works better here as at this time of year the top string (5 panels) will be in full sunlight about 20-30 minutes before the bottom string (4 panels), so the bottom string isn't pulling the top string power down. Its trivial in the overall scheme of things but split strings still work better.
Edit - also there's an overall power limit for a single string which you may well exceed with 9 panels (it does on a G1, not sure about G3).