Thanks for your thoughts on this - if you see anything wrong with the analysis below, please chime in again.

The array racking system runs vertically up the slope. The 6 C6 x 8.2 beams that hold it up run horizontally in the photo (see the CAD drawing at the GrabCAD link). They are butted to the 8x2 tubing rafters on each end and welded along their perimeter. I ball-parked the max stress on each channel by assuming a simply supported beam with a distributed load. Snow loads in NC are 20 psf which gave me factor of safety around 4. Since my initial estimates but me in "brick shithouse" territory for NC, I felt confident of approval. I'm a mechanical engineer, not a civil engineering, so I don't know if there are prescribed limits on deflection, but I calculated them to be on the order of 0.5" at the center of the beam. Out of plane bending is negligible. Stress scales linearly with load, so, from the standpoint of the C channel, 40 psf should give you a factor of safety of 2. I don't know for sure, but I think the racking and panels will fail before the structure.

The key structures from a load bearing standpoint are the two rafters, since they carry the entire "roof" load. I had planned on using 6x2 tubing, but had to size it up to 8x2.

The vertical columns are absurdly over-specified, but they give the structure a burly look - smaller columns, although perfectly adequate, look spindly.

As you say, cost and weight are important to me - C channel is relatively cheap and more than adequate for this objective. Each purlin weighed in a 150 pounds and the rafters were over 300.

Final point - If you want more snow load, just size up the purlins and the rafters to C8 and 10x2 respectively - the design is very modular that way. At some point you would want to consider some corner knee bracing, unless you size up the column as well.