Yes, but the clamps I've found designed for that sort of use are quite expensive, and add a substantial margin to the project cost - and they're not needed if you can weld it up, or have someone else weld it up.
As I understand NEC from talking to various people and reading quite a bit of it myself, someone else can do the frames for a homeowner installed solar project, but "rails and up" has to either be the homeowner or a licensed electrician, because the rails are typically considered part of the grounding system and therefore electrical work.
In any case, costs doing it yourself are far, far lower than paying someone else to do it. And ground mount is an awful lot nicer to work with than roof mount.
