My Current Off-The-Grid system, located in Swellendam, South Africa 6740, as of March 2022:
•    Kodak OG 5.48 located 22 meters from panels [installed March 2022]
•    8-300W 72 cell Enersol[3] &/or Renewsys[5] panels [hooked up 8S, oriented to the NE and roof mounted at 45 degrees]
•    2-US3000B Pylontech Batteries [installed Feb 2020]
•    Yamaha EF5500FW Generator

Currently this system works for me without using the generator, unless there's more than one totally cloudy day, in which case I turn off the 100W pond aerator [which is designed to only be needed when the sun shines] and/or use the gas burner rather than the electric kettle.

I would like to add a bit more power to the system and am asking this forum for your recommendations - R15,000 for 4 more 300W panels and mounts, OR R25,000 for a Pylontech US3000C?

If I add more panels, the specs say that the PV Array MPPT Voltage Range for a Kodak OG 5.48 is 120-450Vdc [with an 80A Max Charging Current], and I have read in topics here and elsewhere that it would be best to stay at least 20% away from the voltage extremes, which changes the preferred range to 144-375Vdc. Currently 8X45.65VOC=365.2VOC from the panels.

If I add 4 more panels it seems best to change to a 6S2P configuration, giving me 273.9VOC.

In the design of my current or proposed panel configuration, does the above seem correct and/or is there something else I should consider?

Also, sometimes when I use the generator and there's still a small amount of solar, the led screen flips back and forth from bypass to PV as a source. With a little more solar it stays on both. The default and current setting for the Charger Source Priority is Solar and Utility in order for both to charge the batteries at the same time, but should I be concerned?

And lastly, ever since I got the new inverter it occasionally has a ringing sound. The attached audio file below was recorded on an iPhone about 15cm from the unit, but it is quite noticeable several meters away. Luckily it's in my workshop and I only notice it a few times a day, and then only for about 20 seconds at a time for a few cycles, with only the occasional fan noise about 99% of the time. I have not found any correlation with fan, load, input or anything else. My supplier/installer says its normal, but it would not be acceptable if it was anywhere closer to where I spend more time. Any thoughts?

I few things to think about.

At what time is you batteries full. If you add 1 more your array my not be able to fully charge 3 of them.

If you what to add panels I would split it 6S2P config.

Thanks Jacques - I appreciate the input