Series vs parallel over strings on Outback fm80 charge controller

[mahendra]

I know this probably came up on the forum before but I am puzzled if I am missing some knowledge on mppt charge controllers and solar panels.

The system is 12v off grid .All items mentioned are on hand .It's just a question of the 10-60w panel configuration.

I have 10 60w bp solar panels with the following specs
STC Power Rating Pmp (W)   60
Open Circuit Voltage Voc (V)   21.0
Short Circuit Current Isc (A)   3.87
Voltage at Maximim Power Vmp (V)   16.8
Current at Maximim Power Imp (A)   3.56
Panel Efficiency   10.8%
Fill Factor   73.8%
Power Tolerance   -3.00% ~ 3.00%
Maximum System Voltage Vmax (V)   600

My thought are to put these in two series strings of 5 to save on wire breakers ease of installation etc.

I friend of mine however ,advised against series strings and suggested that  5 parallel strings of two in parallel(basically 10strings on 5breakers) should be done basing  his ideas that each panel would not be protected by breakers and that there would be losses due to the series configuration.

I honestly do not see much merit in this .Please share your thoughts.Are the losses due to series strings justifiable?

[FNG]

Usually keeping the voltage a little lower is more efficient. If it was mine I would likely go 5 strings of 2 as well provided the wiring supports it and wont cause a ton of voltage drop.

That said an argument for 2 strings of 5 would be in low light the controller has more voltage to work with.

At the end of the day if the wire is right and the array is not shaded I suspect the difference is almost unmeasurable. The FM60 will run cooler though with 5 strings of 2