Photovoltaic Roofing Tie Layer System for Adhesion
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Solution Overview
Problem
The challenge lies in forming a long-lasting physical connection between photovoltaic elements and roofing substrates, particularly when the photovoltaic elements have low surface tension, and adhesion issues arise, especially around the periphery of the photovoltaic elements.
Innovation Solution
A tie layer system is introduced between the encapsulated photovoltaic element and the roofing substrate, comprising a polymeric material with specific surface tension and viscoelastic properties, which provides enhanced adhesion and can withstand severe outdoor conditions, including a configuration where the distance between the substrate and the photovoltaic element varies to reduce thermomechanical stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If photovoltaic elements with low surface tension are used, then device performance and light transmissivity are improved, but adhesion to roofing substrate deteriorates
Solution Approach 1:
A tie layer system comprising a first tie layer and a second tie layer is introduced as an intermediary between the photovoltaic element and the roofing substrate. The first tie layer (e.g., polyvinylidene fluoride or polyacrylonitrile) provides compatibility with the low surface tension encapsulant materials, while the second tie layer (e.g., asphalt-comprising material) ensures strong adhesion to the roofing substrate, thereby resolving the adhesion problem without compromising device performance
Solution Approach 2:
The tie layer system uses composite material structure combining different materials with complementary properties. The first tie layer material (fluoropolymer or polyacrylonitrile) and second tie layer material (asphalt-comprising material) are combined to achieve both compatibility with photovoltaic elements and strong bonding to roofing substrates, solving the adhesion issue while maintaining the benefits of low surface tension encapsulant materials
2Ease of manufacture
If uniform distance between substrate and photovoltaic element is maintained, then manufacturing simplicity is improved, but thermomechanical stress resistance deteriorates
Solution Approach 1:
The distance between the roofing substrate and the photovoltaic element is made non-uniform, with a first distance at the periphery and a second distance at the center, where the first distance differs from the second distance. This local variation in geometric quality allows the structure to accommodate thermomechanical stresses differently across the element, improving reliability while maintaining manufacturing feasibility through defined geometric parameters
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 tie layer system ensures strong and durable adhesion between the photovoltaic elements and the roofing substrate, maintaining bond strength over an extended period, even in harsh outdoor conditions, thereby enhancing the performance and longevity of photovoltaic roofing elements.
Implementation Method 1
comprising a polymeric material with specific surface tension and viscoelastic properties, which provides enhanced adhesion
Implementation Method 2
components that convert light energy into electrical energy. Such 'photovoltaic cells' are often made from semiconductor-type materials
Data Source
AI summary
The present invention relates generally to photovoltaic devices. The present invention relates more particularly to photovoltaic roofing products in which a photovoltaic element is joined to a roofing substrate. In one embodiment, the present invention provides a photovoltaic roofing element comprising: an encapsulated photovoltaic element having a top surface and a bottom surface, a top layer material at its top surface and a bottom layer material at its bottom surface; a roofing substrate having a top surface; and a tie layer system disposed between the encapsulated photovoltaic element and the roofing substrate and joining the bottom surface of the encapsulated photovoltaic element to the top surface of the roofing substrate.