We're in the process of installing PV right now, so I've been looking into this recently. The micro inverter solution is better when there's partial shading, bu

We're in the process of installing PV right now, so I've been looking into this recently. The micro inverter solution is better when there's partial shading, but the micro inverters do not have higher efficiency than the string inverters. If anything, the assertion seems to be that they actually will have lower efficiency because they generally operate at higher temperature, being up on the roof. And contrary to the idea about string inverters needing thicker wires, because the AC wiring runs at 240V but the PV DC cabling typically runs at 400-600V, you need larger wires for the micro inverter solution. (But in either cases, resistive losses in the wires are pretty negligible, tenths of a percent in our case.)