This section provides technical documentation of the physical and empirical models that form PlantPredict’s prediction engine. Each page describes a specific model or algorithm used to simulate solar PV system performance, from solar resource assessment through grid-delivered power including optional battery energy storage.
The Models & Algorithms section documents the calculation methods used in PlantPredict Version 12 to predict energy production from utility-scale solar photovoltaic systems. These models translate solar physics and electrical engineering principles into quantitative predictions of system performance under varying environmental and operational conditions.The prediction engine is organized into four main stages that correspond to the physical energy conversion process:
From solar resource characterization (sun position, horizontal irradiance components, and system geometry) to effective plane-of-array irradiance:
Sun Position & Extraterrestrial Irradiance: Solar position algorithm, sunrise/sunset times, extraterrestrial irradiance, and correction
Horizontal Irradiance Data Processing: Weather data quality control and, if needed, diffuse-direct
System Geometry: Fixed-tilt and single-axis tracker orientations, including tracking algorithm (true tracking, backtracking, or terrain-aware backtracking)
Models: Converting horizontal irradiance components to plane-of-array irradiance, including 3D transposition
Shading Models: Horizon shading, diffuse sky-view, direct beam shading (2D, infinite shed 3D, or detailed 3D scene), and electrical shading effects
Plane-of-Array Irradiance: Soiling, incidence angle modifiers, spectral corrections, and bifacial irradiance gain
Summary: Concise description of the model purpose and outputs
Inputs: Table listing all input parameters with symbols, units, and descriptions
Outputs: Table listing all output parameters with symbols, units, and descriptions
Detailed Description: Complete mathematical description of the model, including equations and algorithmic steps
References: Academic and technical references for the model
Overview pages within each stage provide navigation and describe the relationships between models within that section. The Prediction Model Flow page provides a complete walkthrough of the calculation sequence.
This documentation describes models as implemented in PlantPredict Version 12. Where Version 12 differs from previous versions, those differences are explicitly noted. New features in Version 12 include:
Site-Level 3D Scene Shading: Polygon clipping algorithm for fast, accurate shade calculations across entire site
Terrain-Aware Backtracking (TABT): Optimization of tracker angles accounting for local terrain slopes
3D Transposition: Bay-to-bay (tracking systems) or rack-to-rack (fixed-tilt systems) irradiance variations in 3D scene calculations
Enhanced Bifacial Modeling: Improved rear-surface irradiance calculations with view factors
Quadratic AC Collection Losses: Load-dependent AC collection system losses
Battery Energy Storage: Dispatch algorithms, degradation modeling, and PV+storage integration
