Just finished a big project mounting the solar panels on my bus. I would say I averaged one panel a day for the installation as I was doing it by myself.

I installed ten LG375N2W-G4 panels on the top of my forty foot bus. These panels are 375 maximum watts apiece.

Here's the head on view from the front of the bus:



Here's a view looking back along the top of the bus:



Here's a side view of the first three panels:



In this view you can see that the first two panels are mounted in a slope for hopefully a little bit of aerodynamics though I know that this is probably a dead zone given the almost flat front ends on our buses.

This arrangement only adds about an inch to the clearance height of the bus. I didn't continue with the panels going straight back so as to give the air-conditioner hot exhaust a chance to go upwards and not heat the following panels which would affect their efficiency.

Given the poor aerodynamics of our buses all reports that I have heard is that there is no change in fuel efficiency for mounting solar panels. I don't have a base line on this bus, though the previous owner reported 9 MPG; which given his other statements I would discount.

Here's a side view of the last seven panels:



Note the very last panel behind the rear air-conditioner is also mounted low to allow the hot air to raise.

I think a nice side effect of this arrangement is that the roof will be shaded and the solar panels should have good airflow to help cool them. Also most of the rain will hit the panels and then run off the sides.