Need Advice on a 2.8 Xantrex PV Array System

[stevenh]

The system I'm building:
Xantrex GT2.8 NA 240/208UL grid tie inverter.
208/240 Vac
Input voltage, Maximum Power Point range Certified operating range: 195–550 VDC.
(Unit is operable as low as 193 VDC.)
Absolute maximum array open circuit voltage 600 VDC
Maximum input current 15.4 ADC (240 V), 14.9 ADC (208 V)
Maximum array short circuit current 24 ADC

The panels:
Rated Power (Pmax) 240W
Maximum Power Voltage (Vpm) 29.7V
Maximum Power Current (Ipm) 8.08A
Open Circuit Voltage (Voc) 36.9V
Short Circuit Current (Isc) 8.62A
Module Efficiency 14.8%
Series Fuse Rating 15A
Power Tolerance 0 ± 3%
Maximum System (DC) Voltage 1000V/DC (IEC)

The plan is to run 14 panels (2 strings of 7 in series) running the 2 arrays in parallel.

Is my math correct? That'll be 258.3 Vdc running at 16.16A for a total of 3360Wdc Max. I've been told that I should add enough cells to be 10-15% above the rating of the inverter. Is this correct? Does my math add up, and is this the best configuration for efficiency? Or, should I be running a single series array with 13 panels (479Vdc 8.08A)?

I'm new to this so please bear with me.

[Naptown]

Switch inverters to a Power1 which will allow the low voltage input and in a 3KW size as you are a bit over powered with the Xantrex you are considering.

[stevenh]

Switch inverters to a Power1 which will allow the low voltage input and in a 3KW size as you are a bit over powered with the Xantrex you are considering.

I've already purchased the Xantrex. It was a deal I couldn't pass on. Now I need to match the panels to the inverter.

Should I just go with 12 240s in a single series array?

[Naptown]

Non temperature corrected Voc on those panels is 518V If you use the coldest temp and the NEC table and multiply by 1.25 it comes in over the 600V
Here's where location matters.
If you are tropical and the temp never drops below 70 you could put all 14 in series
If you live in alaska or the great white north you need to compensate for temperature coefficient. (this will be on the spec sheet of the module and expressed as a % per degree C. Remember to start at 25C and count from there as that is the starting point for this.