A protective fence is a really good idea for that size panel.  Not only can it help shield from the windload but also shield from flying lawnchairs, tree branches and the other stuff that are more likely to break the panel up.

Consider adding a shock absorber from a car or truck across the pivot joint.  A the speeds that the tracking happens, the hydraulic damping shouldn't be too much of a load.  In the case of a broken worm gear, it will prevent whole panel flopping in the wind like a fish on the dock.  Actiually it would also provide a redundant mechanical limit of motion also.

Well, My rack is on a similar setup with 4 75 watt Siemans panels. As I recall the polar mount was rated for 1500# no wind speed given on that, however.

I fully intend to double the size one day and will not be concerned that the mount can handle it. In my case, I can park the array via software so if I was concerned I could run it all the way over East so it would have less arm on the jack being fully collapsed. My array is roughly 4 X 8 foot so 32 square feet. It does not even move in 40 mph winds near as I can tell. My rack thats bolted to the polar mount is 2" by 3/16" angle iron one top one bottom with panels mounted in one row across.

Frankly, I think you could bolt a pickup to it with no problems on it still tracking. I think balance is likely more of an issue than wind or weight if the structure is stiff and bolted together solidly.

I may go get a pic of it if I get a minute.

Just wanted to pass that on.

I am uploading pictures to the IRC Gallery now. Large for detail so a link to the album is here:

http://www.anotherpower.com/gallery/album57

Cheers.

TomW

The Truth is the Truth, even if no one believes it; and a lie is a lie even if everyone believes it

The pipe is 100mm boiler tube, cemented 2.1 m into the ground, frame is 50mm box, they amount to a little over 8 square metres.

Well, I can't put it much lower, it's about 18" from the ground parked east or west.

Lots to think about here. Alan's pole is an inch bigger diameter than mine, and his array is still a little smaller than I plan.

Tom's will be about the same size as my current array if he doubles the size.

A fence is an OK idea, except it would have to be twelve feet tall and would need to be a long way away so it didn't block the early morning and late afternoon sun.

Hehe, MX60 said I was out of absorbtion by noon and floated five full hours today. I've got four more panels waiting to go up too. Time to buy that electric 'fridge!

Oh, and I had to ditch the self powered (little panel) idea. 12V wouldn't pull it up from it's limits. I had to run 24V out of the battery box to power the tracker.

Volvo Farmer

I'd actually be more woried about the unbalanced wind force from turbulence as the wind goes past a fence than I would be about the unimpeded wind on the panels.  (Of course you might want a fence to keep debris away.  But make sure the fence is sturdy or it will BECOME flying debris in a windstorm.)