Photovoltaic Cell Electroluminescence for Parameter Separation
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Solution Overview
Problem
Existing methods for characterizing photovoltaic modules are unable to provide a quantitative assessment of individual cells' electrical characteristics, especially in modules composed of thin film cells, and fail to distinguish between parallel resistance and dark recombination current effectively.
Innovation Solution
A method involving electroluminescence measurements at varying voltages to determine hierarchical and analytical relationships between electrical parameters of cells, using an electrical model to quantify parameters like leakage resistance and dark current, and solving optimization problems to match measured and computed luminous intensities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single electroluminescence image is used for characterization, then qualitative cell-by-cell judgement is possible, but quantitative assessment of individual electrical parameters cannot be obtained
Solution Approach 1:
The patent applies periodic action by performing electroluminescence measurements at multiple different voltage levels rather than a single voltage. This allows the system to capture how electroluminescence intensity varies with voltage, enabling differentiation between parallel resistance effects and dark recombination current effects, thus achieving quantitative parameter extraction without requiring complex additional hardware
Solution Approach 2:
The patent changes the voltage parameter across multiple measurement steps to extract different electrical characteristics. By measuring electroluminescence at various voltage levels and analyzing the relationships between measurements, the system can quantitatively determine parallel resistance and dark recombination current values from a single electroluminescence imaging system
2Measurement precision
If measurements are taken at a single low voltage, then shunt areas can be highlighted, but distinction between parallel resistance and dark recombination current is not feasible
Solution Approach 1:
The patent performs measurements at multiple voltage levels (low voltage and high voltage) in a systematic sequence. This periodic measurement approach allows the system to distinguish between parallel resistance and dark recombination current by analyzing how electroluminescence responds differently at each voltage level, achieving precise parameter differentiation without requiring continuous monitoring
3Measurement precision
If a single high-voltage image is used, then electroluminescence intensity can be measured, but distinction between series resistance loss and dark recombination current loss is not possible
Solution Approach 1:
The patent implements periodic measurements at both low and high voltage levels. By comparing electroluminescence intensity relationships at these different voltage points, the system can differentiate between series resistance losses and dark recombination current losses, achieving accurate parameter identification through a systematic multi-step measurement procedure rather than requiring complex additional equipment
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 a quantitative evaluation of individual cell electrical features, distinguishing between parallel resistance and dark current, and optimizing module performance by aligning measured and computed luminous intensities.
Implementation Method 1
characterizing of photovoltaic modules by means of the observation of a light emitted by an electroluminescence phenomenon
Data Source
AI summary
The invention relates to a method for electrically characterising the cells of a photovoltaic module. Said method comprises measuring (MES) the light intensity emitted by electro luminescence by each of the cells according to a voltage applied to the module. Said method further comprises determining (RI), based on the measurements of the light intensity emitted by electroluminescence by each of the cells in a first voltage range applied to the module, hierarchical relationships of analytical relationships between first characteristic electrical parameters of the cells. Said method further comprises determining (R2), based on the measurements of the light intensity emitted by electroluminescence by each of the cells in a second voltage range applied to the module, hierarchical relationships of analytical relationships between second characteristic electrical parameters of the cells.