Solid/Solid Phase Change Copolymer for PV Module Thermal Management
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Solution Overview
Problem
Existing photovoltaic module backsheets using fluoropolymers and poly(ethylene terephthalate) face issues such as hydrolysis in humid conditions, processing difficulties, high costs, and adhesive failures, while phase change materials with poor dimensional stability at high temperatures reduce electricity production efficiency.
Innovation Solution
Development of solid/solid phase change materials with a polyolefin backbone and crystallizable side chains, specifically poly(ethylene-co-glycidyl methacrylate) and polyethylene glycol, which can be processed into films for photovoltaic modules to regulate temperature and store heat by changing from crystalline to amorphous form between 25°C and 75°C, providing a latent heat of phase change of at least 40 kJ/kg.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If solid/liquid PCMs are used in photovoltaic module backsheets, then heat storage capability is improved, but dimensional stability deteriorates at high temperatures when PCM is in liquid form
Solution Approach 1:
The patent changes the physical state parameter of the PCM from liquid to solid by incorporating it into a polymer matrix, transforming it from a solid/liquid system to a solid/solid system that maintains dimensional stability while retaining heat storage capability through phase transitions
Solution Approach 2:
The patent creates a composite material system where the PCM is embedded in a polymer matrix, combining the heat storage properties of the PCM with the structural stability of the polymer, achieving both energy storage and dimensional stability
2Reliability
If fluoropolymers and PET are used for backsheets, then weathering resistance and mechanical strength are improved, but processing difficulty and cost increase
Solution Approach 1:
The patent modifies the chemical composition parameters of the backsheet materials, replacing fluoropolymers and PET with alternative polymers that maintain protective functions while improving processability and reducing costs
Solution Approach 2:
The patent substitutes expensive fluoropolymer materials with more economical polymer alternatives that can achieve similar protective performance, reducing material costs while maintaining reliability
3Reliability
If multiple polymer layers are used in backsheets, then functional performance is improved, but adhesive failure risk increases in long term outdoor use
Solution Approach 1:
The patent merges multiple polymer layers into an integrated multi-layer structure where layers are bonded through co-extrusion or chemical bonding, eliminating the need for separate adhesives and preventing adhesive failure over time
Solution Approach 2:
The patent removes the adhesive layer from the multi-layer backsheet structure, replacing it with direct bonding between polymer layers, thereby eliminating the source of adhesive failure while maintaining functional performance
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 solid/solid phase change materials effectively regulate temperature and maintain dimensional stability, enhancing the efficiency and longevity of photovoltaic modules by scavenging heat and improving electricity production without the drawbacks of traditional materials.
Implementation Method 1
capable of scavenging and storing excess heat by changing from crystalline to amorphous form
Implementation Method 2
providing a latent heat of phase change of at least 40 kJ/kg
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
The present invention relates to phase change materials (PCMs) which may be used with photovoltaic (PV) modules. More specifically, solid/solid PCMs having a polyolefin backbone polymer and a crystallizable side chain are provided. Preferably, the solid/solid PCM has a copolymer backbone having a polyolefin repeating unit, and the crystallizable side chains are grafted onto the copolymer backbone. Most preferably, the copolymer is poly(ethylene-co-glycidyl methacrylate) (PE-co-GMA), and polyethylene glycol (PEG) is the crystallizable side chain. Photovoltaic modules and backsheets for photovoltaic modules having solid/solid PCMs are also provided.