Re: Shading effect question
The "ideal" central (one) inverter would be to have all 10 panels in series connected to a 2+kW GT inverter.
Assuming that the minimum operational voltage of the inverter would support 8 panels in series ( Vmp array > Inverter low voltage)--then it should "gracefully" support one to two panel shading...
You could get into issues where you may "lose" 1/2 a panel's worth of energy from shading on the Enphase vs a "whole" panel with the inverter string (probably similar with the Enphase too--Like RCinFLA says, depends on how the shade falls and how the diodes are arranged).
If, the GT single inverter's low string voltage requires 10 panels minimum--then any shading of one to two panels will potentially "kill" the GT inverter's output until the shading is resolved. So--It depends on a lot of different issues (temperature of array, ambient temperatures too).
20x BP 4175B panels (replacement) + Xantrex GT 3.3 inverter for 3kW Grid Tied system + Honda eu2000i Inverter/Generator for emergency backup.