Yusuf

And then the current goes to over 17A per string. Using 2 strings in parallel you might end up with the MPPT throttling if there is only 1 MPPT input.
Once again we can't just look at the Voc. Sunsynk with 2 MPPT seems fine.

It'll be a lot more reduced if the MPPT gets fried...
But the number of panels in series depends on the Voc mostly, and 650Wp panels available today generally have much lower Voc than 550Wp or 450Wp panels.

The choice should be simple. Does one run the risk of damaging the inverter with all in series or think you might loose a few watt with no damage.  Just the waiting time to have the inverter repaired with no PV system should be enough reason to use 2Px6S.

Hi Joe, 
you are 100% correct, you have to many panels on one string… after getting some professional advice I landed up using 16x 470 watt panels… 8 panels per string just for safety purposes… in future if I don’t find the same panels I can connect all 16 panels on one string by connecting 8 in parallel… but that’s another story.
 
about your setup, if you connected  6 panels on each string it won’t effect your solar production because your panels will still be hitting the same amount of sun time… your inverter will combine both string solar production… even if it did effect your production I would still only put a maximum of 8 for the safety of your inverter. Someone told me that they just make the 150v startup voltage with 4 panels on one mppt so I would suggest going 6 panels per string per mppt. I think you just looking for trouble have 12 panels on 1 mppt.