> Yes, my client has tested them for 2 years now. =A0We mount ours on a
> gimbal (?), so that it always
> stays level when the tracking PV array moves.

> It turns out that here in Arizona you are required to measure the wind
> speed and present a minimal load for the tracker, otherwise the footer
> (concrete foundation) requirements are enormous. The =A0county engineer
> measures our wind device and watches the shutdown before licensing the
> site.

I assume that the minimal load is when the wind is over a certain speed.

F ~=3D 0.5 x D x A x Cd x V^2

F  force, Newton
A area, m^2  (flat plate equivalent projected with Cd=3D1)
D air density kg/m^3
V velocity m/s
Cd  drag coefficient - assume unity.


Or ~~ V^2.A/16  kg/m^2

eg 30 m/s ~~ 60mph ~=3D 50 kg/m^2

Add a moment arm of a metre or few and that can get severe




      Russell

--=20
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