Nonlinear

Done. Good luck and let us know how it goes.

Done. Good luck and let us know how it goes.

Thanks @P1000
I'm happy to report the FTDI converter works.
Results of dmesg
[160585.535658] usb 1-1.4: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[160585.535666] usb 1-1.4: Product: US232R
[160585.535672] usb 1-1.4: Manufacturer: FTDI
[160585.535679] usb 1-1.4: SerialNumber: FT4WLQTJ
[160585.571538] usbcore: registered new interface driver ftdi_sio
[160585.571583] usbserial: USB Serial support registered for FTDI USB Serial Device
[160585.571745] ftdi_sio 1-1.4:1.0: FTDI USB Serial Device converter detected
[160585.571823] usb 1-1.4: Detected FT232RL
[160585.574534] usb 1-1.4: FTDI USB Serial Device converter now attached to ttyUSB1
No reboot required. 
Next I'll try to make up a little breadboard with the chip you suggest above and play around to see if I can get it to work.

I'm confused. I thought you were selling two of them. Was about to PM you but then I saw this.

I was dumb enough to make that mistake (just as the "split"/"solar wars" happened). I explained my situation to Manie and he was gracious enough to come to an agreement with me. So kudos to him for that alone.
I admit that ICC is not perfect and has had (and still has) it's issues, but usually Manie does try to fix whatever bugs may crop up. From that perspective alone it is worth it. Like other posters above have said, I could probably write this myself, but why bother spending hundreds of hours (that I can rather spend on billable work) when something is available out there.
My only bugbear now: the software is tied to hardware, these Pi boards are great, but nothing lasts forever and especially not on the Highveld during summer, no matter what protection you think you have in place.
Finally, my last 2c: I really enjoy these kinds of discussion, open/fair exchanges of views are good for everyone and broaden my horizons.

My understanding is that centurionsolar and ICC have parted ways. You may instead want to go to the source and contact @Manie or [email protected].

To be honest that was a little bit of future proofing that probably was not necessary. My intention has always been to use the Axpert as a learning curve and finally settle for a more long term (dare I say) higher quality inverter. It seems from what I've seen over the last while that the majority of inverters and panels are moving towards higher voltage/lower current and thus thicker wire is not required but just in case I do ever need to drop my voltages and up my current then all I need to do is swap out the fuses and possibly breakers and I should be good to go.