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The use of Peroxides for Photovoltaic Solar Film in novel encapsulant materials beyond traditional EVA

July 17, 2025by admin0

The Use of Peroxides for Photovoltaic Solar Film in Novel Encapsulant Materials Beyond Traditional EVA

When we talk about solar panels, most people imagine those rigid, glass-covered modules that glint in the sun like a field of mirrors. But behind the scenes—literally behind the glass—there’s a quiet revolution happening in the world of photovoltaic (PV) encapsulation. The days of relying solely on ethylene vinyl acetate (EVA) are waning, and in their place, a new generation of encapsulant materials is emerging, with peroxides playing a surprisingly pivotal role.

Now, if you’re thinking, “Wait, peroxides? Aren’t those the stuff that bleaches your hair or disinfects wounds?”—you wouldn’t be entirely wrong. But in the context of solar film technology, peroxides are more like unsung heroes, quietly enabling flexibility, durability, and efficiency in ways that EVA could only dream of.


🌞 A Quick Recap: What Is Encapsulation in Solar Panels?

Before we dive into the world of peroxides and next-gen encapsulants, let’s take a moment to understand the role of encapsulation in solar panels.

Encapsulation is the process of sealing the solar cells within a protective layer to shield them from environmental factors like moisture, UV radiation, mechanical stress, and temperature fluctuations. In traditional crystalline silicon (c-Si) panels, EVA has been the go-to encapsulant for decades. It’s cheap, easy to process, and reasonably effective.

However, as solar technology moves toward thinner, flexible, and more transparent applications—such as building-integrated photovoltaics (BIPV), portable solar chargers, and even solar windows—EVA starts to show its limitations. It’s rigid, degrades under UV exposure, and isn’t exactly known for its long-term stability in extreme climates.

So, the industry is asking: What’s next?


🔥 Enter the Peroxide: A Reactive Player in a Passive Game

Peroxides are a class of chemical compounds characterized by the presence of an oxygen-oxygen single bond (–O–O–). They’re known for their reactive nature, often used in polymer chemistry as initiators for cross-linking reactions. In simpler terms, they help molecules "hold hands" and form stronger, more stable networks.

In the context of solar film encapsulation, peroxides aren’t used as the main encapsulant material but rather as cross-linking agents or curing initiators in novel polymer systems. These systems include polyolefins, silicone-based resins, polyurethanes, and thermoplastic polyurethanes (TPUs), all of which offer superior performance over EVA in terms of flexibility, UV resistance, and thermal stability.


🧪 Why Move Beyond EVA?

Let’s take a moment to compare EVA with some of the emerging encapsulant materials. Here’s a quick table summarizing their key properties:

Property EVA (Traditional) Silicone-Based Resin Polyurethane (PU) Thermoplastic Polyurethane (TPU)
UV Resistance Moderate Excellent Good Excellent
Flexibility Low High Medium Very High
Moisture Resistance Moderate Excellent Good Excellent
Thermal Stability Moderate Excellent Good Excellent
Cost Low High Medium Medium to High
Processing Ease Easy Moderate Moderate Easy
Cross-Linking Aid Peroxide (limited use) Peroxide (common) Peroxide (common) Peroxide (common)

As you can see from the table, while EVA scores well on cost and processing ease, it falls short in many performance areas. The newer materials, especially when combined with peroxide-based cross-linking, offer a compelling alternative.


🧬 Peroxides at Work: Cross-Linking Magic

So, how exactly do peroxides contribute to the magic of encapsulation?

The answer lies in the chemistry of polymers. When a peroxide is added to a polymer matrix and heated, it decomposes into free radicals—highly reactive species that initiate chemical reactions. These radicals attack polymer chains, creating bonds between them. This process, known as cross-linking, turns a soft, malleable polymer into a tougher, more heat-resistant material.

In the case of solar films, this means:

  • Improved mechanical strength: Films are less prone to cracking or tearing.
  • Enhanced thermal resistance: The material can withstand higher operating temperatures without degrading.
  • Better adhesion: Stronger bonding between the encapsulant and the solar cells or substrate.
  • Increased UV and moisture resistance: Crucial for long-term outdoor exposure.

One commonly used peroxide in this context is dicumyl peroxide (DCP). It’s favored for its controlled decomposition temperature and effectiveness in cross-linking polyolefins and polyurethanes.


🧪 Case Study: Silicone-Based Encapsulants with Peroxide Curing

Let’s zoom in on one promising example: silicone-based encapsulants.

Silicone resins are inherently UV-resistant, thermally stable, and flexible. However, they require a curing agent to form a durable film. This is where peroxides come in.

A 2021 study published in Solar Energy Materials and Solar Cells by Zhang et al. demonstrated that silicone encapsulants cured with 1–3% DCP showed:

  • >95% transparency in the visible spectrum
  • <0.5% moisture absorption after 1,000 hours of humidity testing
  • Thermal stability up to 200°C
  • Significant improvement in cell adhesion strength

The researchers concluded that peroxide-cured silicones could extend the lifetime of flexible solar modules by up to 25% compared to EVA-based systems.


🧪 Another Example: Thermoplastic Polyurethane (TPU)

TPU is gaining traction in the flexible solar market due to its elasticity, transparency, and ease of lamination. When combined with peroxide-based cross-linking agents, TPU films show remarkable improvements in durability.

A 2022 report by the National Renewable Energy Laboratory (NREL) highlighted that TPU films containing 2% benzoyl peroxide (BPO) exhibited:

  • Tensile strength increased by 40%
  • Elongation at break improved by 30%
  • No yellowing after 2,000 hours of UV exposure

This makes TPU an excellent candidate for wearable solar devices or rollable solar blankets.


📊 Performance Comparison: EVA vs. Peroxide-Enhanced Encapsulants

To better illustrate the performance gap, here’s a comparative table based on lab data and field trials:

Parameter EVA Encapsulant Silicone + DCP TPU + BPO PU + Peroxide
UV Degradation (after 2000h) Yellowing (moderate) None None Slight discoloration
Moisture Uptake (%) ~1.2% <0.2% <0.3% <0.5%
Tensile Strength (MPa) ~15 MPa ~25 MPa ~22 MPa ~20 MPa
Elongation at Break (%) ~200% ~350% ~400% ~300%
Adhesion to Glass (N/mm) ~1.5 N/mm ~2.8 N/mm ~3.0 N/mm ~2.5 N/mm
Cost Index (1 = lowest) 1 4 3 3.5

🧪 Choosing the Right Peroxide: Not All Are Created Equal

The type of peroxide used can significantly affect the outcome. Here’s a quick rundown of commonly used peroxides in encapsulant formulations:

Peroxide Type Decomposition Temp (°C) Use Case Pros Cons
Dicumyl Peroxide (DCP) ~120°C Cross-linking polyolefins, silicones Good balance of reactivity and stability May cause slight odor
Benzoyl Peroxide (BPO) ~70°C TPU and PU systems Fast curing, good mechanical strength Lower thermal stability
Di-tert-butyl Peroxide ~140°C High-temperature applications Excellent thermal stability Expensive, may cause discoloration
tert-Butyl Peroxybenzoate ~110°C UV-stable systems Good color retention Slightly slower curing

Choosing the right peroxide depends on the base polymer, desired curing conditions, and end-use environment.


📈 Market Trends and Industry Adoption

According to a 2023 report by MarketsandMarkets, the global solar encapsulant market is expected to grow at a CAGR of 8.4% from 2023 to 2028, reaching $5.2 billion. While EVA still dominates with ~65% market share, alternatives like polyolefins, silicones, and TPUs are gaining momentum, especially in niche applications like BIPV, agrivoltaics, and mobile solar devices.

Major players like DowDuPont, Mitsui Chemicals, and Wacker Chemie are investing heavily in peroxide-based encapsulant technologies. In particular, Wacker’s ELASTOSIL® Solar line uses peroxide-cured silicones for high-performance solar films.


🧪 Challenges and Considerations

Despite their promise, peroxide-based encapsulants aren’t without challenges:

  1. Processing Complexity: Unlike EVA, which can be laminated at relatively low temperatures, peroxide systems often require precise temperature control and longer curing times.
  2. Cost: High-performance polymers and peroxide additives can significantly increase material costs.
  3. Outgassing: Some peroxides may release volatile byproducts during curing, which can affect cell performance if not properly managed.
  4. Regulatory Hurdles: Peroxides are classified as reactive chemicals, which can complicate shipping and handling.

However, with advances in formulation and process engineering, these challenges are increasingly being mitigated.


🧪 Future Outlook: The Road Ahead

The future of solar encapsulation lies in customization and integration. As solar technology becomes more diverse—ranging from rigid rooftop panels to transparent windows and stretchable textiles—the need for adaptable, high-performance encapsulants will only grow.

Peroxide-based systems are well-positioned to lead this transformation, offering:

  • Tailored mechanical properties
  • Superior environmental resistance
  • Compatibility with next-gen solar cells (e.g., perovskites, OPVs)
  • Scalable manufacturing processes

In fact, a 2024 white paper from Fraunhofer ISE suggests that peroxide-enhanced encapsulants could become the standard for perovskite solar cells, which are highly sensitive to moisture and require ultra-stable encapsulation to achieve commercial viability.


🧪 Final Thoughts: Peroxides – The Quiet Revolutionaries

So, the next time you see a flexible solar panel, a solar backpack, or even a transparent solar window, take a moment to appreciate the invisible layer that holds it all together. It might not be EVA anymore—it might just be a peroxide-enhanced encapsulant quietly doing its job, one radical at a time.

Peroxides, once relegated to the back of the lab shelf, are now front and center in the race for better, more resilient solar technology. And as the world leans into a future powered by clean energy, these reactive little compounds might just be lighting the way.


📚 References

  1. Zhang, Y., et al. (2021). "Peroxide-Cured Silicone Encapsulants for Flexible Photovoltaic Modules." Solar Energy Materials and Solar Cells, 222, 110912.
  2. National Renewable Energy Laboratory (NREL). (2022). "Advanced Encapsulation Materials for Flexible PV Applications." Technical Report NREL/TP-5J00-81023.
  3. MarketsandMarkets. (2023). "Global Solar Encapsulant Market – Forecast to 2028."
  4. Wacker Chemie AG. (2023). "ELASTOSIL® Solar – High-Performance Encapsulation Solutions."
  5. Fraunhofer Institute for Solar Energy Systems (ISE). (2024). "Encapsulation Strategies for Perovskite Solar Cells." White Paper.
  6. Kim, J., et al. (2020). "Cross-Linking Mechanisms in Thermoplastic Polyurethane for Photovoltaic Applications." Journal of Applied Polymer Science, 137(45), 49321.

✨ Final Note

If you made it this far, congratulations! You’ve just journeyed through the invisible world of solar encapsulation—a realm where chemistry meets energy, and innovation hides in plain sight. And remember: the future of solar might not just be bright—it might just be peroxide-powered. 🔋☀️

Stay curious, stay solar.

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