PV Module Backtracking for Substring Shading Control
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Solution Overview
Problem
Existing PV module systems face inefficiencies due to shading issues, which reduce energy production as the orientation of PV modules changes throughout the day, leading to partial or complete shading of lower rows of PV cells, disrupting energy output and requiring inefficient backtracking methods to mitigate these losses.
Innovation Solution
A multi-phase backtracking method that dynamically adjusts the orientation of PV modules by calculating the solar position and projected solar zenith to prevent shading of both upper and lower substrings within the maximum tracker angle range, optimizing tracker angles to maximize energy collection and reduce Fresnel effect-induced light reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the orientation of PV modules is changed throughout the day to track the sun, then energy collection is improved, but shading of lower rows of PV cells occurs which reduces energy production
Solution Approach 1:
The PV module is divided into multiple substrings (upper and lower substrings) with different orientations. The upper substring is oriented to track the sun for maximum energy collection, while the lower substring is oriented to minimize shading from adjacent modules. This segmentation allows each substring to independently optimize its function, resolving the contradiction between tracking the sun and avoiding shading.
Solution Approach 2:
The upper and lower substrings are given asymmetric orientations relative to each other and to the adjacent PV modules. Instead of both substrings having the same orientation, they are deliberately oriented at different angles. This asymmetric configuration allows the upper substring to face the sun directly while the lower substring is positioned to avoid being shaded by neighboring modules, thus maintaining energy production.
2Object-affected harmful factors
If backtracking is used to prevent shading, then shading is reduced, but energy collection efficiency decreases
Solution Approach 1:
Rather than moving the entire PV module assembly in traditional backtracking, the invention segments the module into substrings that can be independently oriented. This allows the lower substring to be positioned to avoid shading without requiring the whole module to backtrack, thereby maintaining better sun exposure and energy collection efficiency while still preventing harmful shading.
Solution Approach 2:
Different parts of the PV module (upper and lower substrings) are given different local orientations optimized for their specific functions. The upper substring optimizes for sun tracking while the lower substring optimizes for shading avoidance. This local quality differentiation allows each substring to perform its function optimally without compromising overall system productivity.
3Area of stationary object
If PV modules are placed in rows with limited spacing, then land use efficiency is improved, but row-to-row shading increases reducing energy output
Solution Approach 1:
By segmenting each PV module into multiple substrings with different orientations, the invention allows for tighter row spacing without increasing shading problems. The lower substrings are oriented to minimize their shading impact on adjacent rows, enabling more efficient land use while maintaining adequate light exposure for energy production.
Solution Approach 2:
Different substrings within each module have different local orientations that are optimized for their position in the row. This creates a pattern where shading is distributed and minimized across the array, allowing rows to be placed closer together while still preventing harmful row-to-row shading effects.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach increases energy production by enhancing photon collection and exposure time, especially in weak sunlight conditions, and improves inverter operation by increasing incoming power, thereby facilitating more efficient energy harvesting and reducing shading-related power drops.
Implementation Method 1
PV modules may include a first array of photovoltaic (PV) cells and a second array of PV cells
Implementation Method 2
A target tracker angle may be identified based on the PSZ and the maximum tracker angle range and used as a tracker angle control setpoint
Data Source
AI summary
A method may include calculating a solar position of the Sun and a projected solar zenith (PSZ) relative to a position of a photovoltaic (PV) module. The method may include determining whether an orientation of the PV module is configurable to prevent shading of an upper substring of the PV module while shading a lower substring of the PV module. Responsive to determining that such an orientation is not configurable, the method may include determining whether the orientation of the PV module is configurable to prevent shading of both the upper substring and the lower substring. Responsive to determining that such an orientation is not configurable, the method may include determining whether the PSZ is within a maximum tracker angle range. A target tracker angle may be identified based on the PSZ and the maximum tracker angle range and used as a tracker angle control setpoint.