Photovoltaic Spacer Mitigates Thermal Stress on Interconnectors
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Solution Overview
Problem
Photovoltaic modules with polymer-based encapsulation structures face degradation issues due to high thermal expansion coefficients, leading to interconnector rupture and inoperability during thermal cycling, which is not effectively addressed by reducing polymer thickness or reinforcing with fibers, as it compromises regulatory compliance and energy efficiency.
Innovation Solution
Incorporating a spacer made of a material with a lower modulus of elasticity than the encapsulation material into the interconnector coverage area to accommodate thermal deformations, reducing stress concentration and preventing interconnector rupture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the thickness of the polymer encapsulation structure is reduced, then the weight of the photovoltaic module is decreased, but the module becomes unable to pass regulatory certification tests for impact and bending-strength
Solution Approach 1:
The patent employs a composite encapsulation structure combining a thermoplastic polymer matrix with dispersed elastomeric particles. This composite formulation maintains adequate thickness for mechanical strength while reducing overall weight, achieving both lightweighting and structural integrity requirements for regulatory certification
Solution Approach 2:
The patent modifies the physical and chemical parameters of the encapsulation material by incorporating elastomeric particles with specific glass transition temperatures and molecular weights. These parameter changes enhance the material's toughness and impact resistance, allowing thinner sections to meet strength requirements
2Reliability
If the polymer encapsulation structure is reinforced with fibres or fabrics to make the module stiffer and more resistant to thermal cycling, then the resistance to thermal cycling is improved, but the processes become substantially modified and industrial development is complicated and slowed down
Solution Approach 1:
The patent uses an elastomeric-polymer composite system where elastomeric particles are dispersed within the thermoplastic matrix. This composite approach provides enhanced thermal cycling resistance through improved flexibility and stress distribution, while maintaining compatibility with existing lamination processes, avoiding substantial process modifications
Solution Approach 2:
The elastomeric particles are distributed throughout the encapsulation material to provide localized flexibility and stress absorption capabilities. This local quality enhancement allows the material to accommodate thermal expansion differences without requiring complex reinforcing structures or process changes
3Reliability
If the polymer encapsulation structure is reinforced with fibres or fabrics to make the module stiffer and more resistant to thermal cycling, then the resistance to thermal cycling is improved, but the optical properties are modified and energy efficiency is degraded
Solution Approach 1:
The elastomeric-polymer composite uses transparent or translucent elastomeric particles that maintain optical transparency. This allows the composite to provide enhanced thermal cycling resistance through improved mechanical flexibility while preserving optical properties and energy efficiency, unlike opaque fiber reinforcements
Solution Approach 2:
The elastomeric particles provide localized mechanical flexibility and stress absorption without forming continuous opaque structures. This local reinforcement approach maintains overall optical transparency of the encapsulation material, preventing degradation of energy efficiency while improving thermal cycling resistance
4Reliability
If a spacer made of material with lower modulus of elasticity than the encapsulation material is incorporated into the interconnector coverage area, then the resistance to thermal cycling is enhanced, but the device complexity increases
Solution Approach 1:
The elastomeric particles act as intermediary elements between the rigid thermoplastic matrix and the metal interconnectors. These particles provide a compliant interface that absorbs thermal stresses, protecting interconnectors from rupture while maintaining overall structural integrity with minimal added complexity
Solution Approach 2:
The multi-phase composite structure combines rigid thermoplastic polymer with softer elastomeric particles, creating a gradient of mechanical properties. This composite architecture provides the necessary compliance in the interconnector coverage area without requiring separate spacer components or complex multi-layer structures
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
The spacer effectively mitigates thermal stress concentrations, enhancing the photovoltaic module's resistance to thermal cycling without compromising regulatory compliance or energy efficiency.
Implementation Method 1
they have a high tendency to deform under the effect of temperature, characterized by a high coefficient of thermal expansion (CTE)
Implementation Method 2
The elastomeric particles have a glass transition temperature between -50° C. and 0° C. and a number-average molecular weight between 10 000 and 100 000 g/mol
Data Source
AI summary
The invention relates to a photovoltaic module including a photovoltaic unit having a plurality of photovoltaic cells electrically connected in series and spaced apart from one another, the adjacent photovoltaic cells being electrically connected pairwise by a metal interconnector which extends at least in part into an interconnection space separating said adjacent photovoltaic cells, an encapsulation structure made of a polymer-based encapsulation material, which sandwiches the opposite sides of the photovoltaic cells, defining a region of cell coverage, and the interconnector in the interconnection space, defining a region of interconnector coverage, and a spacer incorporated into the encapsulation structure and partially superposed on the interconnector in the region of interconnector coverage, the spacer being made of a material having, at least at a temperature of −40° C., a modulus of elasticity lower than the modulus of elasticity of the encapsulation material.