Photovoltaic Module Inspection Using Selective Laser Luminescence
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Solution Overview
Problem
Current methods for inspecting photovoltaic (PV) modules, such as I-V curve recording and electroluminescence (EL) imaging, are time-consuming, inaccurate, and often require electrical contacting, making them inefficient for large-scale outdoor inspections, especially under varying weather conditions.
Innovation Solution
A mobile inspection system using a movable detector unit with a laser source and imaging system that selectively illuminates portions of the PV module, capturing photoluminescence and induced luminescence data without electrical biasing, allowing for contactless and efficient detection of defects across large PV installations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electroluminescence imaging is used for accurate defect detection, then measurement precision is improved, but the inspection process becomes time-consuming due to required electrical biasing
Solution Approach 1:
The patent replaces the electrical biasing system with an optical illumination system. Instead of applying electrical current to generate luminescence, the system uses a light source to illuminate the PV module and capture photoluminescence images. This substitution eliminates the time-consuming electrical connection process while maintaining defect detection capability through optical means.
Solution Approach 2:
The patent introduces an optical intermediary (light source and camera system) between the inspector and the PV module. The light source acts as a mediator to stimulate luminescence without requiring electrical contact, and the camera captures the emitted light to reveal defects. This intermediary system bridges the gap between non-contact inspection and accurate defect detection.
2Measurement precision
If traditional EL imaging is used for defect detection, then measurement precision is improved, but device complexity increases due to electrical contacting requirements
Solution Approach 1:
The patent replaces complex electrical contacting mechanisms with a simple optical system. Instead of requiring electrical connections, clamps, or contact probes, the system uses only a light source and camera to inspect PV modules. This substitution dramatically reduces device complexity while maintaining the ability to detect defects through luminescence imaging.
3Ease of operation
If sunlight-based illumination is used for outdoor inspection, then ease of operation is improved, but reliability deteriorates due to weather dependence
Solution Approach 1:
The patent makes the inspection system self-sufficient by carrying its own light source. Instead of relying on external sunlight that varies with weather conditions, the system generates its own illumination through an integrated light source. This allows the inspection to proceed reliably under any ambient lighting conditions, whether sunny, cloudy, or nighttime.
4Ease of operation
If contactless inspection methods are used, then ease of operation is improved, but measurement precision deteriorates compared to electrical contacting methods
Solution Approach 1:
The patent substitutes electrical contacting with optical stimulation and detection. The light source stimulates the PV module to emit photoluminescence, and the camera captures this emission with sufficient precision to detect defects. This optical substitution maintains measurement precision while achieving contactless operation, as the luminescence signal provides rich information about cell health and defects.
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
Enables accurate and efficient detection of various defects in PV modules, including cell cracks and series resistance issues, without the need for electrical connections or weather-dependent illumination, facilitating rapid and reliable inspections both day and night.
Implementation Method 1
a light source, in particular a laser source, configured to emit an illumination beam; means for selectively directing the illumination beam onto respective portions of the light-receiving surface so as, when the illumination beam is directed onto a first portion of the light-receiving surface, to only illuminate the first portion
Implementation Method 2
EL of solar cells occurs when current is injected into the cell and radiative recombination of carriers causes light emissions, which peak at the wavelength corresponding to the energy of the bandgap of the solar cell semiconductor material. Capturing the emitted photons with a camera detector sufficiently sensitive to the luminescence peak wavelength is denoted EL imaging
Data Source
AI summary
The present disclosure relates to an inspection system, in particular a mobile inspection system, for outdoor inspection of photovoltaic modules in situ, the inspection system comprising a movable detector unit and a processing unit. The detector unit is configured to obtain, when positioned at a user-controllable position spaced apart from a photovoltaic module of a photovoltaic power system, luminescence data from a light-receiving surface of said photovoltaic module. The detector unit may include a light source, in particular a laser source, configured to emit an illumination beam, means for selectively directing the illumination beam onto respective portions of the light-receiving surface so as, when the illumination beam is directed onto a first portion of the light-receiving surface, to only illuminate the first portion while leaving a corresponding first remaining portion of the light-receiving surface unilluminated by the illumination beam.