Yeah and, of course, the good thing about the DC run is you don't have to worry about voltage Rise on the AC side and risking inverter drop out from over voltage. That is typically my primary concern when designing a long AC run with losses kinda being secondary. With DC, just adding a panel or two may be much cheaper than big wire.I admit I didn't think about voltage drop over 400ft. However if you run DC in that pipe it may be an option to just compromise on voltage drop. There was a paper in Solar Pro magazine a few years back that argued that upsizing for DC voltage drop was break-even on cost.