Planned Mount on 6x6 treated posts - comments?

Hey all,

Planning an install at our family cabin, looking for recommendations, comments or suggestions on our plan to date. This is just a plan so far, none of the mounting supplies have been purchased.

Due to logistical reasons, a roof mount on our cabin isn't going to cut it and as such we needed to figure out an alternative. We have found the best patch of ground, south facing -- clear of shading for the peak hours of the day from 10am - 4pm. To protect the panels, primarily against theft we've decided to get them off the ground. Fully understand that a determined bad guy can and will get them, but figured that if a thief needs to pull out a ladder, it less likely they will swipe the panels as we present less of an easy opportunity.

We've looked at a few different options from a steel pole to utility poles and have landed on a pair of pressure treated 6x6 posts in 16' length as the best option. Our area gets very little freezing, some snow but loads of rain in the winter months (Southern Vancouver Island). The treated posts appear to be the lowest cost, and are likely the easiest option to work with given the remote nature of the cabin and available tools.

Plan is to place two posts approximately 3' apart. Base of the posts would be down a minimum of 4', sitting on a bed of packed gravel (for drainage), and then cemented within a sonotube. Sonotube would stick up about 6" above grade to ensure proper drainage and no earth around the base of the post. I will then install a cross brace between the two posts at the top, and a second approximately 3' down.

To mount the 3 panels (each 56" x 28" = 10sqft & 25.5lbs), I have built a rectangular braced frame out of treated 2x4's. I have screwed the aluminum standoffs directly to this frame using Stainless Steel hardware. I will also place a plastic shim between the aluminum standoff and the frame to prevent corrosion from the pressure treated chemical compounds. In order to angle the frame/panels, I had the idea of using Heavy Duty gate hinges that would affix to the top of the frame and screw into the top brace. I would then use a pair of support "legs" at the bottom of the frame to adjust the angle (which gives me the option to increase/decrease the panel angle seasonally if I choose). I plan to install a guy-wire opposite the load, and ether side of the posts for increased stability. If you can picture it, the frame and posts form a giant #4 if viewed from their side.

I was concerned about wind loading on the structure. The panels would not be exposed to significant wind in their location -- they are protected by the cabin, and surrounding forest, but I wanted to understand the risks. I was able to find that the strength of a 6x6 post ranges from 1000-1200 PSI (wet to dry). I've also calculated that a wind speed of 50mph would place a load of approximately 400lbs on the panels/frame (total area of 30sqft) so it appears that the structure should have plenty of strength.

Anyhow, I'm not an engineer. I think my plan is pretty solid, but would appreciate any feedback or concerns on something I might be missing here as I only want to do this one time :-)