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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.

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Models in This Section

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Fixed-Tilt Arrays

Static orientation with user-defined tilt and angles.

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True Tracking (Single-Axis)

Base tracking algorithm that rotates modules to minimize angle of incidence. Within the tracking plane (perpendicular to the rotation axis), modules face the sun directly.

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Backtracking Models

Shade avoidance algorithms that reduce rotation angle to prevent row-to-row shading:
  • 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): 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 Angles: Custom rotation angles specified per tracker, allowing manual override of calculated backtracking positions. Each tracker can have its own rotation angle.

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Irradiance Optimization

Optimizes tracker angle to maximize plane-of-array irradiance:
  • PlantPredict: Built-in optimization algorithm
  • Array Technologies API: External optimization via ATI DiffuseStow API

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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

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Incidence Angle

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

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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 and User-Defined Angles operate independently and should not be combined with Irradiance Optimization or Wind Stow.