Phi angle (without limits)

[IB31]

What does the Phi angle (without limits) indicates in the Unlimited tracker 2D model. How it is different from the BT limiting Phi angle

[Michele Oliosi]

The Phi angle generally represents the rotation angle around the tracker axis. For a horizontal axis tracker, it is 0 when the tracker is horizontal, so it roughly corresponds to a tilt angle.

The BT limiting Phi angle is the maximum Phi angle reached in the non-backtracking (i.e. sun-tracking) regime. If the sun gets any lower, the backtracking is activated.

The Phi angle (without limits) means the Phi angle if there was no backtracking and there were no tracker mechanical limits. It can be higher than the BT limiting Phi angle or the tracker mechanical limits.