Photovoltaic Module Polymer Recesses Thermal Expansion
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Solution Overview
Problem
Photovoltaic modules with polymer faces face thermal expansion issues due to differing thermomechanical properties of materials, leading to stress-induced delamination, breakage, and warping, especially when subjected to temperature variations.
Innovation Solution
Incorporating recesses with 'soft' jointing materials in the polymer layers to act as expansion joints, reducing stress by creating rupture zones and allowing for differential expansion without compromising structural integrity or optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If polymer materials with high coefficient of expansion are used for front and/or rear faces, then the module can be made lighter and more flexible, but thermal expansion stresses cause delamination, breakage, and warping
Solution Approach 1:
The polymer layer is segmented by creating recesses that form expansion joints, dividing the continuous polymer face into sections that can independently expand and contract. This segmentation allows the module to accommodate thermal expansion without generating excessive stresses that would cause delamination or warping, while maintaining the lightweight advantage of polymer materials.
Solution Approach 2:
The polymer layer is modified locally by creating recesses at specific positions and orientations. These localized features serve as expansion joints that selectively accommodate thermal expansion in specific directions while maintaining structural integrity in other areas. The local modification allows the polymer face to expand without compromising overall module reliability.
2Strength
If thick polymer layers are used, then optical performance and protection are improved, but thermal expansion stresses increase
Solution Approach 1:
The thick polymer layer is divided into sections by recesses forming expansion joints. This segmentation allows the thick polymer to maintain its protective strength while accommodating thermal expansion through the creation of controlled rupture zones, preventing the buildup of excessive thermal stresses.
Solution Approach 2:
The polymer layer is locally modified with recesses that create expansion joints. These localized features allow the thick polymer to expand and contract without generating excessive stresses, maintaining both the protective strength of the thick layer and the reliability of the module under thermal cycling.
3Reliability
If recesses are created in polymer layers, then thermal expansion stresses are reduced, but structural continuity is compromised
Solution Approach 1:
The recesses in the polymer layer create flexible expansion joints that allow the polymer face to bend and expand without compromising overall structural continuity. The polymer material's inherent flexibility, combined with the recess geometry, enables the structure to accommodate thermal expansion while maintaining integrity.
Solution Approach 2:
The Young's modulus of the jointing material is specifically selected to be lower than that of the polymer material, creating a compliant expansion joint. This parameter change allows the recess areas to deform under thermal stress, accommodating expansion while maintaining the overall structural continuity and stability of the polymer layer.
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 solution effectively mitigates thermal expansion stresses, enhancing the module's durability and reliability under temperature fluctuations while maintaining optical and protective functions.
Implementation Method 1
the first and second layers provided with the recesses being made of at least one polymer material in which are formed recesses constituting expansion joints
Implementation Method 2
said at least one of the first and second layers provided with the recesses being of a single piece, the recesses being at least partially occupied by a jointing material said to be soft having a Young's modulus at room temperature lower than the Young's modulus at room temperature of the polymer material
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
The main subject matter of the invention is a photovoltaic module (1) comprising at least one first transparent layer (2) forming the front face of the photovoltaic module (1), a plurality of photovoltaic cells (4), an encapsulating assembly (3) encapsulating the plurality of photovoltaic cells, a second layer (5) forming the rear face of the photovoltaic module (1), characterised in that at least one of the first (2) and second (5) layers consists of a polymer material, in which recesses (7) are formed that constitute expansion joints, produced as a one-piece component, and in that the recesses (7) are at least partially occupied by a so-called "soft" joining material having a Young's modulus less than that of the polymer material of said at least one of the first (2) and second (5) layers and a thickness less than or equal to that of said at least one of the first (2) and second (5) layers. The recesses (7) are at least partially through-recesses.