#### Jalapeno1042

##### New Member

- Joined
- Aug 30, 2022

- Messages
- 11

I got partway started with a 24 volt ground mount system when I discovered (at my wife's urging) that I need a permit since I live in a township in AZ. Even though its on my property (~ 1 acre). Sparing you all a hilarious and ridiculous diatribe, here's where this is at. I have 6 panels ("modules") mounted in 2 "panels" sets, 4 in one and 2 larger ones in the other, all of which are mounted to my latitude of 32°. They are concreted in the ground to a depth of 12 inches by 14 gauge slotted angle iron at each corner. For the permit, among other things, I have to calculate wind uplift for each set of panels at a design wind speed of 90 miles per hour. (this is actually an old value since ASCE 7-05 has been replace by ASCE 7-10, which is 115 mph. but who's complaining?).

The formula for such calculation apparently is F = A (projection area of panels) x P (wind pressure) x Cd (drag coeff.) x Kz (exposure coeff) x Gh (gust response).

After several days of hunting, head shaking and rarely used language, I think I have figured it out for the smaller 4 panel array. But the answer I get seems awfully high: 395.6 lbs. Subtract the weight of the array and it becomes 332.2 lbs. So my anchor system of angle iron, concrete, and A307 1/2 inch bolts and nuts would have to hold down that force before being ripped out of the ground.

Do these numbers seem right to anyone? Does anyone else have to go through this? IS ANYBODY OUT THERE????

The formula for such calculation apparently is F = A (projection area of panels) x P (wind pressure) x Cd (drag coeff.) x Kz (exposure coeff) x Gh (gust response).

After several days of hunting, head shaking and rarely used language, I think I have figured it out for the smaller 4 panel array. But the answer I get seems awfully high: 395.6 lbs. Subtract the weight of the array and it becomes 332.2 lbs. So my anchor system of angle iron, concrete, and A307 1/2 inch bolts and nuts would have to hold down that force before being ripped out of the ground.

Do these numbers seem right to anyone? Does anyone else have to go through this? IS ANYBODY OUT THERE????