Solar Cell Module Impedance Diagnostic System
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Solution Overview
Problem
Current diagnostic methods for solar cell modules struggle to detect degradation of sealing materials and electrical insulation issues, which can lead to reduced performance and failure, especially due to moisture intrusion and corrosion, making it difficult to determine the condition of solar cell modules accurately.
Innovation Solution
A diagnostic method and system that measures frequency characteristics of impedance during periods when solar cells do not generate power, using a frequency-variable impedance measuring device connected to the solar cell module, allowing for the determination of equivalent circuit constants and detection of changes in the condition of the module, including the sealing material's degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If monitoring current, voltage, or power generation amount is used to check solar cell module operation, then the operating condition can be monitored, but it is difficult to determine whether the module is operating normally because power generation varies with external factors like solar radiation and weather
Solution Approach 1:
The patent changes the measurement parameter from power generation characteristics (current, voltage, power) which are affected by external factors, to impedance characteristics which are intrinsic to the module's internal state. By measuring impedance at multiple frequencies and analyzing resonance characteristics, the system can determine module condition independent of solar radiation and weather conditions.
2Measurement precision
If high frequency impedance measurement is used to detect module degradation, then degradation states can be detected, but it is difficult to detect characteristic degradation of sealing material optical transmittance and electrical insulation
Solution Approach 1:
The patent segments the impedance measurement into multiple frequency components and analyzes different aspects of the impedance spectrum separately. By measuring at multiple frequencies and analyzing resonance characteristics at each frequency, the system can identify specific degradation modes including sealing material degradation that would be masked in a single-frequency measurement.
Solution Approach 2:
The patent adds the frequency dimension to the impedance measurement by conducting measurements at multiple frequencies rather than a single frequency. This dimensional expansion allows the system to capture different physical phenomena occurring at different frequency ranges, enabling detection of sealing material degradation through changes in resonance characteristics.
3Measurement precision
If equivalent circuit model analysis is used to obtain characteristic variables, then module-specific parameters can be determined, but the complexity of the diagnostic system increases
Solution Approach 1:
The patent introduces an equivalent circuit model as an intermediary between the raw impedance measurements and the degradation assessment. The model provides a framework for interpreting complex multi-frequency impedance data by representing the module's electrical characteristics through standardized circuit elements, simplifying the analysis while maintaining measurement precision.
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 enables quantitative detection and monitoring of solar cell module degradation, including sealing material changes, allowing for timely maintenance and preventing failures by identifying issues in electrodes, wiring, and insulation resistance.
Implementation Method 1
measuring frequency characteristics of impedance between two output cables of the solar cell module, and frequency characteristics of impedance between one of the two output cables and the frame
Implementation Method 2
measuring frequency characteristics including a resonance point of impedance between two output cables of the solar cell module, and frequency characteristics including a resonance point of impedance between one of the two output cables and the frame
Data Source
AI summary
A method for diagnosing a solar cell module includes an analysis of measuring frequency characteristics including a resonance point of impedance between two poles of a solar cell module, and frequency characteristics including a resonance point of impedance between an output cable and a frame, and determining equivalent circuit constants of the solar cell module, and a determination of comparing the equivalent circuit constants determined in the analysis with equivalent circuit constants obtained previously to determine change in condition of the solar cell module.