> ## Documentation Index
> Fetch the complete documentation index at: https://docs.plantpredict.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Tracker & Array Orientation Overview

export const PlaneOfArrayIrradiance = () => <Tooltip tip="Solar irradiance on the tilted module surface (beam + diffuse + reflected); drives PV power generation.">
    plane-of-array irradiance
  </Tooltip>;

export const AngleOfIncidence = () => <Tooltip tip="Angle between the sun's rays and the perpendicular to a surface; 0° when sun is directly facing the surface.">
    angle of incidence
  </Tooltip>;

export const Azimuth = () => <Tooltip tip="Horizontal angle measured clockwise from north; applies to sun direction or surface orientation.">
    azimuth
  </Tooltip>;

Tracker & Array Orientation models determine the angular position of PV modules for each timestep. PlantPredict supports fixed-tilt arrays and horizontal single-axis trackers with multiple tracking modes and override options.

## Models in This Section

### [Fixed-Tilt Arrays](fixed_tilt_arrays)

Static orientation with user-defined tilt and <Azimuth /> angles.

### [True Tracking (Single-Axis)](true_tracking)

Base tracking algorithm that rotates modules to minimize <AngleOfIncidence />. Within the tracking plane (perpendicular to the rotation axis), modules face the sun directly.

### Backtracking Models

Shade avoidance algorithms that reduce rotation angle to prevent row-to-row shading:

* **[Standard Backtracking](backtracking/standard_backtracking)**: Standard geometric backtracking for flat terrain. Modules rotate back just enough to avoid row-to-row shading, assuming a uniform plant with a single angle applied to the entire DC field.
* **[Terrain-Aware Backtracking (TABT)](backtracking/terrain_aware_backtracking)**: Advanced backtracking accounting for terrain slopes between rows, designed to avoid row-to-row shading (Version 12). Each tracker can have its own rotation angle based on local terrain geometry.

### [User-Defined Tracking Angles](user_defined_tracking_angles)

Custom rotation angles supplied via time-series data, bypassing the normal tracking algorithm entirely. Angles can be defined at the DC field level using time-series data (one angle per timestep for the entire field) or, with a 3D scene, on a per-tracker basis using a Time Series Schedule.

### [Irradiance Optimization](irradiance_optimization)

Optimizes tracker angle to maximize <PlaneOfArrayIrradiance />:

* **PlantPredict**: Built-in optimization algorithm
* **Array Technologies API**: External optimization via ATI DiffuseStow API

### [Wind Stow](wind_stow)

Protective stow position during high wind conditions:

* **PlantPredict**: Threshold-based stow using wind gust speed
* **Array Technologies API**: External stow calculation via ATI Wind Stow API

### [Incidence Angle](incidence_angle)

Calculates angle between sun vector and module normal for fixed-tilt and tracking systems.

## Tracker Angle Hierarchy

For single-axis trackers, the final rotation angle is determined by priority:

**Wind Stow** > **Irradiance Optimization** > **Backtracking** > **True Tracking**

Higher priority models override lower priority results when active.

Note: Terrain-Aware Backtracking operates independently and should not be combined with Irradiance Optimization or Wind Stow. User-Defined Tracking Angles bypass the hierarchy entirely—the supplied angle is used directly.