New array rack design question

[boondox]

I am getting ready to add 9 panels to my array. These are 245 watt panels of the typical size. My last rack I massively overbuilt and while it has held up well, I would like to do something a little cheaper and easier this time. These panels will be mounted on a shipping container, next to the current array of 18 panels. Weather-wise we are moderate, we get some storms with up to 60 mph winds most winters.

So, 9 panels in three runs in portrait orientation. I am thinking of running two ~ 20' lengths of box stock and then two runs of unistrut perpendicular to the box stock for each row of panels. The high end of the array would have legs of box stock about 10" tall. The array will cantilever past the shipping container and be attached where it passes over the wall. Of course there will be bracing where necessary for sheer and and where the panels cantilever past the container.

My question is what size and thickness of box stock? As a chronic over builder my first instinct is to go 3" with 1/8" walls. But I know that is more than I need. Would 2" with 11 gauge walls be sufficient? The difference in price is large.

 

[OzSolar]

You'll be just fine. "less is more" has become my new mantra of recent years for a large variety of reasons.

There's a lot to discuss but the big picture is that my suggestion is to identify how many nines are you are designing for. Designing to six nines (6 Sigma) makes almost no sense 99% of the time.

 

[dopeassjackson]

With out proper support any size box tube would be to small.
Have you priced out the thicker taller strut or C channel if you can weld? Square steel is prety pricy stuff.