I've been a bit perplexed about why one would use conduit INSIDE the house for roof top mounted PV. I'm guessing that it's needed and is a holdover from non micro inverter grid tied systems. You are working with high DC voltages there and it might be good to protect those wires more than others. For me, romex works just fine for micro inverter systems. The only place I plan to have conduit is between this
SolaDeck Roof Mount Passthrough Enclosure, 0786-3R
and the central junction box right at the panels, about 3 feet or less if I plan it right. I can use a smaller gauge romex for that short length.