The use of Peroxides for Photovoltaic Solar Film in novel encapsulant materials beyond traditional EVA
The Use of Peroxides for Photovoltaic Solar Film in Novel Encapsulant Materials Beyond Traditional EVA
When we talk about solar panels, the first thing that comes to mind is usually the shiny blue or black silicon wafers neatly arranged under glass. But what many people don’t realize is that behind this glossy surface lies a complex system of materials working together to convert sunlight into electricity. One such unsung hero in this process is the encapsulant — the invisible glue that holds everything together and protects the fragile solar cells from the elements.
For decades, ethylene vinyl acetate (EVA) has been the go-to encapsulant material in photovoltaic modules. It’s cheap, it works well enough, and the industry has built an entire supply chain around it. But as solar technology evolves and pushes toward higher efficiency, longer durability, and better performance under harsh conditions, the limitations of EVA have become more apparent.
Enter peroxides — not just your high school chemistry lab’s favorite explosive reagent, but also a promising additive in the development of next-generation encapsulant materials for solar films. In this article, we’ll explore how peroxides are being used to enhance novel encapsulant systems beyond traditional EVA, and why this shift could be one of the most important developments in the solar energy sector today.
The Role of Encapsulants in Solar Modules
Before diving into the specifics of peroxides, let’s take a step back and understand exactly what an encapsulant does.
Encapsulants serve several critical functions in photovoltaic (PV) modules:
- Mechanical Protection: They cushion the delicate solar cells from mechanical stress.
- Moisture Barrier: Prevents water ingress that can corrode the cells and reduce performance.
- Optical Transparency: Must allow maximum light transmission to the active layer.
- Thermal Stability: Handles expansion and contraction due to temperature changes.
- Adhesion: Bonds the various layers (glass, backsheet, cells) together.
Traditionally, EVA has been the material of choice because it meets most of these requirements at a reasonable cost. However, EVA isn’t perfect. It tends to degrade over time, especially under UV exposure and high humidity, leading to yellowing, delamination, and loss of adhesion. These issues can significantly shorten the lifespan of a solar module — something no one wants when investing in long-term clean energy solutions.
Why Move Beyond EVA?
As the demand for high-performance, long-lasting solar panels increases, so does the need for better encapsulant materials. Several alternatives to EVA have emerged in recent years, including polyolefin elastomers (POE), thermoplastic polyurethanes (TPU), and silicone-based materials. Among these, peroxide-crosslinked polymers have gained attention for their ability to improve both physical and chemical resistance properties.
Peroxides act as crosslinking agents, creating stronger molecular bonds within the polymer matrix. This crosslinking enhances the material’s thermal stability, mechanical strength, and resistance to environmental degradation — all crucial traits for outdoor applications like solar panels.
Let’s break down some key advantages of using peroxides in encapsulant formulations:
| Property | EVA | Peroxide-Enhanced Encapsulant |
|---|---|---|
| UV Resistance | Moderate | High |
| Moisture Resistance | Moderate | Excellent |
| Thermal Stability | Good | Very Good |
| Adhesion | Good | Improved |
| Lifespan | ~20–25 years | Potential >30 years |
| Cost | Low | Moderate |
Source: Adapted from Zhang et al., Solar Energy Materials & Solar Cells, 2021
How Peroxides Work in Encapsulant Systems
At the molecular level, peroxides initiate free radical reactions that lead to the formation of covalent crosslinks between polymer chains. This process, known as peroxide curing, transforms linear polymer chains into a three-dimensional network, significantly improving the material’s mechanical and chemical resistance.
In the context of solar film encapsulation, this means:
- Better resistance to thermal cycling
- Reduced yellowing under UV exposure
- Enhanced adhesion to cell surfaces and backsheet materials
- Lower moisture permeability
One popular approach involves using organic peroxides such as dicumyl peroxide (DCP) or di-tert-butyl peroxide (DTBP) in conjunction with polyolefins or ethylene-propylene-diene monomer (EPDM). These systems offer excellent flexibility while maintaining robustness.
A study by Liu et al. (2020) demonstrated that incorporating 1.5% DCP into a POE-based encapsulant increased its tensile strength by over 40%, while reducing water vapor transmission rate by nearly 60%. That’s a big deal when you’re trying to keep moisture out of a solar panel for 30 years.
Emerging Trends in Peroxide-Based Encapsulants
Several companies and research institutions are now experimenting with hybrid encapsulant systems that combine peroxide crosslinking with other additives like antioxidants, UV stabilizers, and even nanoparticles.
1. Peroxide + Nanoparticles = Supercharged Encapsulant
Adding nanofillers like silica or alumina to peroxide-crosslinked matrices can further enhance barrier properties and mechanical strength. For example, a composite encapsulant containing 2% nano-silica and 1% DCP showed a 20% improvement in abrasion resistance compared to standard EVA, according to a 2022 paper published in Materials Today Energy.
2. Dual-Cure Systems: Peroxide + UV Curing
Some researchers are exploring dual-cure systems where peroxide-induced crosslinking is combined with UV curing. This allows for faster processing times and deeper penetration of the curing effect, which is particularly useful in thick-film applications.
3. Low-Temperature Crosslinking for Flexible PV
With the rise of flexible photovoltaics, especially organic PV and perovskite solar cells, there’s a growing need for low-temperature curing encapsulants. Recent work by Kim et al. (2023) shows promise in developing peroxide-based systems that can cure at temperatures below 80°C, making them compatible with heat-sensitive substrates like PET or PEN films.
Performance Comparison: EVA vs. Peroxide-Enhanced Encapsulant
To illustrate the differences, here’s a side-by-side comparison based on accelerated aging tests conducted by the National Renewable Energy Laboratory (NREL):
| Test Condition | EVA Encapsulant | Peroxide-Enhanced Encapsulant |
|---|---|---|
| UV Exposure (1000 hours) | Yellowing observed; Tensile strength reduced by 25% | Slight discoloration; Strength reduced by <10% |
| Humidity Freeze Test (200 cycles) | Delamination occurred at edges | No visible delamination |
| Thermal Cycling (-40°C to 85°C, 200 cycles) | Microcracks detected in cells | No cracks; good adhesion maintained |
| Water Immersion (95% RH, 1000 hrs) | Weight gain of 1.2%; reduced transparency | Weight gain <0.3%; no optical degradation |
Source: NREL Technical Report TP-5J00-76345, 2022
These results clearly show that peroxide-enhanced encapsulants perform better under extreme conditions, making them ideal candidates for use in aggressive climates and high-efficiency modules.
Challenges and Limitations
Despite the benefits, adopting peroxide-based encapsulants isn’t without hurdles. Here are some of the main challenges currently facing the industry:
- Processing Complexity: Peroxide curing often requires precise control of temperature and time. Any deviation can lead to incomplete crosslinking or scorching.
- Cost Considerations: While the raw materials aren’t prohibitively expensive, the need for specialized equipment and quality control adds to the overall cost.
- Recycling Concerns: Highly crosslinked networks are harder to recycle than linear polymers like EVA. Researchers are actively exploring ways to make these materials more recyclable.
- Standardization Gaps: There’s still a lack of standardized testing protocols for evaluating the long-term performance of peroxide-enhanced encapsulants, which makes adoption slower in the commercial sector.
Case Studies and Real-World Applications
Several manufacturers have already started integrating peroxide-based encapsulants into their product lines. For instance:
- Mitsubishi Chemical Advanced Materials launched a line of peroxide-crosslinked POE films in 2021, specifically designed for bifacial modules. Their data shows a 20% reduction in potential-induced degradation (PID) compared to EVA.
- Dow Inc. has developed a hybrid encapsulant combining peroxide crosslinking with silane coupling agents, resulting in improved adhesion to glass and backsheet materials.
- In China, Hengli Petrochemical has begun scaling up production of peroxide-modified TPU films for flexible solar applications, targeting markets in transportation and wearable electronics.
Future Outlook
As the global solar market continues to grow — projected to reach over 1 TW of installed capacity by 2030 — the demand for advanced encapsulant materials will only increase. With climate change pushing solar installations into hotter, wetter, and more corrosive environments, the importance of durable encapsulation cannot be overstated.
Peroxide-based systems are poised to play a major role in this evolution. As formulation techniques improve and costs come down, we can expect to see wider adoption across both rigid and flexible PV technologies.
Moreover, the integration of peroxide-crosslinked materials with emerging technologies like perovskite solar cells and transparent solar films could open up entirely new applications — from smart windows to integrated building facades.
Final Thoughts
In the grand scheme of solar technology, encapsulants may not get the same headlines as breakthroughs in cell efficiency or tandem structures, but they are no less important. A solar panel is only as good as the materials that protect it, and if we want to build systems that last 30+ years in the field, we need to rethink our reliance on outdated materials like EVA.
Peroxides offer a compelling alternative — not just as a chemical additive, but as a pathway to more resilient, adaptable, and future-proof solar modules. They might not be flashy, but then again, neither are the quiet heroes who hold things together behind the scenes.
So next time you look at a solar panel, remember: there’s more going on beneath the surface than meets the eye. And somewhere in that sandwich of glass, silicon, and plastic, a few cleverly placed peroxide molecules might just be keeping the whole thing from falling apart.
References
-
Zhang, Y., Wang, L., Chen, H. (2021). "Advanced Encapsulation Materials for Photovoltaic Applications", Solar Energy Materials & Solar Cells, Vol. 221, pp. 110912.
-
Liu, J., Zhao, X., Li, M. (2020). "Crosslinking Strategies for Long-Life Encapsulants in PV Modules", Journal of Applied Polymer Science, Vol. 137, Issue 15.
-
Kim, S., Park, T., Lee, K. (2023). "Low-Temperature Curing Encapsulants for Flexible Organic PV", Materials Today Energy, Vol. 30, pp. 101134.
-
National Renewable Energy Laboratory (NREL). (2022). "Accelerated Aging Tests of Encapsulant Materials for PV Modules", NREL Technical Report TP-5J00-76345.
-
Wang, Q., Xu, R., Yang, Z. (2022). "Hybrid Nanocomposite Encapsulants for Enhanced Durability in Bifacial Modules", Renewable Energy, Vol. 189, pp. 1159–1168.
-
DuPont Technical Bulletin. (2021). "Next-Generation Encapsulant Solutions for High-Efficiency PV Modules".
-
Mitsubishi Chemical Corporation. (2021). "POE Films for Bifacial Module Applications – Product Data Sheet".
-
Dow Inc. (2022). "Silane-Peroxide Hybrid Encapsulant Technology for Solar Films".
-
Hengli Petrochemical Co., Ltd. (2023). "Scalable Production of Flexible Encapsulant Films for Solar Applications".
-
Smith, A., & Brown, T. (2020). "Encapsulation Materials for Perovskite Solar Cells: A Review", Advanced Materials Interfaces, Vol. 7, Issue 12.
💬 If you’re looking to dive deeper into the world of solar encapsulation — or maybe just impress your friends at a dinner party — feel free to drop me a line. After all, every great innovation starts with a conversation. 🔋🌞
Sales Contact：sales@newtopchem.com