Stiff Polyvinyl Butyral Encapsulant for Solar Cells
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Solution Overview
Problem
The use of highly plasticized poly(vinyl butyral) sheets in solar cell modules is complicated by their softness and tackiness at ambient temperature, requiring refrigeration during shipment and storage, and their processability is impaired by temperature-dependent sliding issues, necessitating a two-step bonding process.
Innovation Solution
A solar cell pre-laminate assembly using a stiff poly(vinyl butyral) sheet with a poly(vinyl butyral) composition containing 10 to 23 wt% plasticizer, positioned next to the light-receiving or back side of the solar cell component, and a second polymeric layer, with the stiff poly(vinyl butyral) sheet serving as both front and second encapsulant layers, allowing for a simplified manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If highly plasticized poly(vinyl butyral) sheets are used in solar cell modules, then penetration resistance is improved, but the sheets become soft and tacky at ambient temperature requiring refrigeration during shipment and storage
Solution Approach 1:
The patent changes the plasticizer content parameter from high (>25 wt%) to low (17-23 wt%) to transform the material properties. This parameter change allows the PVB sheet to maintain adequate penetration resistance while eliminating excessive softness and tackiness, enabling ambient temperature handling without refrigeration.
2Strength
If highly plasticized poly(vinyl butyral) sheets are used, then penetration resistance is improved, but processability is impaired by temperature-dependent sliding issues necessitating a two-step bonding process
Solution Approach 1:
The patent modifies the plasticizer concentration parameter to resolve the processing contradiction. By reducing plasticizer content to 17-23 wt%, the material achieves optimal balance between penetration resistance and processability, eliminating temperature-dependent sliding issues that would require complex two-step bonding processes.
Solution Approach 2:
The patent applies preliminary action by optimizing the plasticizer content during material formulation before manufacturing. This pre-optimization ensures the PVB sheet has appropriate bonding characteristics at ambient temperature, eliminating the need for subsequent complex processing steps.
3Strength
If 5 mm thickness of poly(vinyl butyral) resin composition is used, then encapsulation is improved, but light transmission efficiency is impaired
Solution Approach 1:
The patent employs thin film technology by reducing the PVB encapsulant thickness from 5 mm to approximately 0.76 mm (30 mils). This thin film approach provides adequate encapsulation and protection while maintaining high light transmission efficiency, resolving the contradiction between protection and optical performance.
Data Source
AI summary
A solar cell pre-laminate assembly comprising (i) a solar cell component comprising one or a plurality of solar cells and having a light-receiving side and a back side, and (ii) stiff poly(vinyl butyral) sheet as an encapsulant layer, wherein the stiff poly(vinyl butyral) sheet is positioned next to the light-receiving or the back side of the solar cell component and comprises a poly(vinyl butyral) composition containing about 10 to about 23 wt % of a plasticizer based on the total weight of the composition.A process of preparing solar cell assembly comprising (i) providing a solar cell component and a stiff poly(vinyl butyral) sheet comprising a poly(vinyl butyral) composition containing about 10 to about 23 wt % of a plasticizer based on the total weight of the poly(vinyl butyral) composition, and (ii) encapsulating the solar cell component in a polymer matrix comprising the poly(vinyl butyral) composition.