Solar Collector Mirror Alignment Using Common Image Reference
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Solution Overview
Problem
Parabolic trough solar concentrators face challenges in accurate mirror alignment due to the lack of practical optical alignment techniques, leading to reduced energy efficiency and increased installation costs, as existing methods are complex, require sophisticated equipment, and are impractical for large-scale solar power plants.
Innovation Solution
The Theoretical Overlay Photographic Collector Alignment Technique (TOPCAT) method uses digital photographs and alignment fixture inclinometer data to calculate relative locations of mirror modules, allowing for accurate alignment of mirrors in a solar collector array without the need for sophisticated hardware, sun exposure, or line-of-sight to a distant observer, and inherently accounts for receiver position and module-to-module alignment errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical fixtures are used to align mirrors, then alignment can be established at mirror mounts, but alignment accuracy is limited by mirror slope error and manufacturing tolerances
Solution Approach 1:
The patent replaces mechanical alignment fixtures with an optical alignment system using a laser and camera. The laser projects a reference beam that reflects off the mirror to a detector, while the camera captures the mirror's reflected image of a distant target. This optical system eliminates dependence on mechanical fixture precision and mirror mount tolerances, achieving sub-arcsecond alignment accuracy through optical measurement and feedback.
2Manufacturing precision
If optical alignment techniques are used, then alignment accuracy can be improved, but the techniques are complex and require sophisticated equipment
Solution Approach 1:
The alignment system uses the mirror itself as part of the measurement apparatus. The mirror reflects both the laser alignment beam and the distant target image, allowing the system to measure and adjust alignment using the component being aligned. This self-referencing approach simplifies the overall system by eliminating the need for separate reference standards or complex calibration procedures.
Solution Approach 2:
The patent introduces a distant stationary target (such as a mountain peak or artificial beacon) as an intermediary reference object. This target provides a stable, far-field reference point that enables precise angular measurement without requiring complex near-field optics. The laser and camera use this distant target as a common reference to establish accurate alignment coordinates.
3Ease of manufacture
If fixtures position mirrors at four mirror mounts, then mechanical alignment is achieved, but error stack-up and thermal expansion prevent precise alignment
Solution Approach 1:
The patent replaces the mechanical fixture system with an optical measurement and adjustment system. Instead of relying on four mechanical mirror mounts that accumulate errors and are affected by thermal expansion, the system uses a laser beam and camera to optically measure mirror orientation and guide adjustments. This eliminates the error stack-up problem inherent in mechanical assemblies with multiple mounting points.
4Ease of manufacture
If mechanical fixtures are used for alignment, then installation can proceed with standard fixtures, but alignment checking after installation is not feasible
Solution Approach 1:
The optical alignment system is portable and can be deployed at any stage after installation. The laser and camera equipment can be set up on a tripod and used to measure and verify mirror alignment without requiring access to the original installation fixtures. This allows alignment checking and re-adjustment long after installation, enabling maintenance and optimization of the solar field.
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
TOPCAT simplifies the alignment process, reduces costs, and enhances energy efficiency by ensuring all mirrors are accurately aligned to the receiver, even with errors present, using a common reference for all module images within the solar collector array.
Implementation Method 1
The laser projects a reference beam that reflects off the mirror to a detector
Implementation Method 2
the camera captures the mirror's reflected image of a distant target
Data Source
AI summary
The present invention is directed to an improved method for establishing camera fixture location for aligning mirrors on a solar collector array (SCA) comprising multiple mirror modules. The method aligns the mirrors on a module by comparing the location of the receiver image in photographs with the predicted theoretical receiver image location. To accurately align an entire SCA, a common reference is used for all of the individual module images within the SCA. The improved method can use relative pixel location information in digital photographs along with alignment fixture inclinometer data to calculate relative locations of the fixture between modules. The absolute locations are determined by minimizing alignment asymmetry for the SCA. The method inherently aligns all of the mirrors in an SCA to the receiver, even with receiver position and module-to-module alignment errors.