DIY PV System -- Sizing the Components

There is really not much to "size" on this system.

The wiring that runs from the PV array to the house power distribution panel should be sized to keep a low voltage drop.

This Application note for the 190watt inverter provides a table for choosing the gage of the wire from the array to the house:

http://www.enphaseenergy.com/downloads/EnphaseAppNote_Circuit_Calculations_M190.pdf

In my case with 10 inverters and a 90 ft run, I could have used #12 wire (good for up to 115 ft with 10 inverters), but I decided to use #10 to allow for adding a few more panels at some future date.

Ephase allows up to 15 inverters on one circuit -- this is (15)(190w/inverter) = 2850 watts. After this, a 2nd circuit has to be added.