I downloaded the PV string  tool yesterday.  @Chris HobsonThanks for the nice tool!  I just have a question regarding the entry MPPT I max.  I notice that you have N/A for the Axpert inverters? What is the reason for that?

I have a Mecer SOL-I-AX_5NB inverter  -  (Axpert MKS II 5K  with PVmax 450Vdc).  I notice on the sticker on the side (attached) that it states under the heading Solar charger Mode that the

Maximum input current   = 18A.   Do I have to put it into the spreadsheet or is the current limited by the inverter to 18Amps  hence the N/A?

18Amps seem ridiculously low as 2 strings  will exceed that. Does that mean I can only connect a single string to the inverter? I was hoping to use  2 strings of 5 (or 6) x 405W. My roof area is limited so I have to go for the higher wattage panels.  Any suggestions will be appreciated.

Axpert MKS II 5K.pdf

23 minutes ago, Squonk said:

or is the current limited by the inverter to 18Amps

The current is limited to 18 Amps.

23 minutes ago, Squonk said:

I was hoping to use  2 strings of 5 (or 6) x 405W.

You can always downsize the panels a bit. Look at the difference between the SOT and NOCT ratings of the 370Watt panels in the following data sheet. JAM72S01 PR 365-385 Global_EN_20180726A.pdf . Even when you look at the highest rating and take normal losses into consideration, you should not reach those figures. I believe it is safe to connect 2 strings of six in parallel. (Total 4440 Watts ) 

Thanks for the advice. Now I can  go shopping for panels😄