Photovoltaic Cell Paste Curing with Uniform Light Heating
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Solution Overview
Problem
Existing methods for curing conductive paste in photovoltaic cells result in non-uniform heating due to thermal gradients, leading to potential detachment and reliability issues in photovoltaic modules, especially for silicon heterojunction cells with limited thermal budgets.
Innovation Solution
A method using electromagnetic radiation between 300 nm and 700 nm to cure conductive paste, ensuring uniform heating of photovoltaic cells by volume absorption, reducing thermal gradients, and improving energy conversion efficiency through light soaking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If thermal conduction and convection are used to cure conductive paste, then the paste can be heated to curing temperature, but thermal gradients are created between the face in contact with heating plate and the free face, leading to non-uniform curing and potential detachment
Solution Approach 1:
The patent replaces the mechanical thermal conduction system (heating plates in contact with cell faces) with an electromagnetic radiation system (illumination source emitting light in the 300-700nm range). This optical system penetrates the photovoltaic cell material and heats the conductive paste throughout its volume simultaneously, eliminating thermal gradients and achieving uniform curing without mechanical contact.
Solution Approach 2:
The patent utilizes electromagnetic radiation (light waves) in the 300-700nm range to directly excite and heat the conductive paste material. This electromagnetic energy absorption causes volumetric heating throughout the paste and cell structure, creating uniform temperature distribution and curing the paste simultaneously across all faces, thereby resolving the thermal gradient issue inherent in conventional contact heating methods.
2Reliability
If conventional thermal curing is used, then conductive paste can be cured, but the method causes detachment of conductive tape from cured paste or from cell, reducing electrical reliability
Solution Approach 1:
The patent replaces contact-based thermal heating with electromagnetic radiation heating. The illumination source emits light that penetrates the cell and heats the conductive paste volumetrically without mechanical contact. This eliminates the thermal gradients that cause differential expansion and adhesion failure, thereby preventing detachment of conductive tape and maintaining electrical reliability.
Solution Approach 2:
The patent changes the heating mechanism from thermal conduction (contact-based) to electromagnetic radiation absorption (volumetric heating). By using light in the 300-700nm range that is absorbed by the conductive paste and cell material, the system achieves uniform temperature rise throughout the structure, preventing localized overheating and the resulting adhesion failure that occurs with conventional heating methods.
3Productivity
If silicon heterojunction cells are used, then high efficiency is achieved, but they have limited thermal budget and are sensitive to thermal damage during curing
Solution Approach 1:
The patent replaces contact thermal heating with electromagnetic radiation heating. The illumination source emits light that is absorbed throughout the cell volume, heating the conductive paste and cell material uniformly without creating thermal gradients. This volumetric heating approach is gentler on the silicon heterojunction structure, avoiding localized thermal stress and damage while still achieving the necessary curing temperature.
Solution Approach 2:
The patent uses illumination with specific spectral characteristics (300-700nm range) that can be controlled in intensity and duration. This allows precise control of the thermal budget, delivering just enough energy to cure the conductive paste without exceeding the thermal limits of the sensitive silicon heterojunction cell structure, thereby protecting the cell while achieving curing.
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
Achieves homogeneous curing of conductive paste, enhances module reliability by minimizing detachment risks, and improves energy conversion efficiency of photovoltaic cells.
Implementation Method 1
exposing the first face of the photovoltaic cell to a first electromagnetic radiation comprising at least one component between 300 nm and 700 nm
Implementation Method 2
Conversion of electromagnetic radiation into electric energy is achieved by photovoltaic cells having at least one face illuminated by said electromagnetic radiation
Data Source
AI summary
A method for curing a portion of conductive paste disposed on a photovoltaic cell, the photovoltaic cell including a first face and a second face, the portion of conductive paste being disposed on one of the faces of the photovoltaic cell, the curing method including exposing the first face of the photovoltaic cell to a first electromagnetic radiation including at least one component between 300 nm and 700 nm.