Metal roof solar penetration boot
Make sure that the vent pipe is not going to come up in the middle of a roof panel seam. If it is, the best course of action is move the vent pipe over a few inches and try to center it up in the flat of the roof panel. Believe me, it is far less trouble to relocate the vent pipe now than it will be to relocate it later! If you fail to do this, you will have a roof leak that can only be temporarily stopped.