What is EVA Material？
EVA is one of the most critical encapsulation materials in the production process of solar modules. the selection and performance of EVA will not only affect the appearance and quality of solar modules but also affect the lifetime of solar modules.
The composition and properties of EVA
EVA is the main component of ethylene and vinyl acetate copolymer, plus a variety of additives such as cross-linking agents, thickeners, antioxidants, light stabilizers, and so on.
EVA has excellent flexibility, impact resistance, elasticity, optical transparency, low-temperature bending, adhesion, environmental stress cracking resistance, weather resistance, corrosion resistance, heat sealing, and electrical properties.
The role of EVA
EVA is flexible and has good bonding performance, with good light-transmitting properties and aging resistance of transparent colloids. EVA’s role is to solar cells “on the cover under the pad” seal in the middle, to protect the role of the cell.
At room temperature, EVA is solid, with no viscosity, and poor light transmission. When the EVA is heated to a certain temperature, EVA will melt and bond in contact with it the object. It has a high light transmission rate after melting, which can improve the incidence of light and increase the output power of solar modules.
In addition, in the solar module production process, lamination is the key link, and the parameters of the laminator are set around the characteristics of EVA. Therefore, EVA is critical to the production of solar modules.
Why EVA Film is the Best Choice for Solar Panels?
EVA (Ethylene Vinyl Acetate) encapsulation film is widely used in solar cell encapsulation due to its excellent properties. Its primary role is to protect solar cells and provide mechanical support and electrical insulation under various conditions. The following are the key properties of EVA encapsulation film in terms of water vapor barrier, tensile strength, and electrical strength.
1. Superior Water Vapor Barrier Properties
EVA encapsulation film excels in preventing moisture ingress, which is crucial for the long-term stability and performance of solar cells. Here are its key advantages:
- High Volume Resistivity: EVA film typically has a very high volume resistivity, meaning it effectively resists the flow of electric current, reducing leakage in high-humidity environments and protecting the electronic properties of the cells.
- Low Water Vapor Transmission Rate: EVA film has a low water vapor transmission rate (WTR), which effectively prevents moisture from penetrating into the cell. This helps prevent damage to the electrical performance and structural integrity of the solar cells caused by moisture, thereby extending their lifespan.
These excellent moisture barrier properties make EVA film particularly suitable for solar panels in various climate conditions, ensuring stable operation of the cell components even in harsh environments.
2. Outstanding Tensile Strength
The tensile strength of EVA encapsulation film is a critical indicator of its ability to maintain stability under mechanical stress. It has the following characteristics:
- High Tensile Strength: EVA film possesses high tensile strength, allowing it to maintain its structural integrity when subjected to tensile forces. This is crucial for solar cells to withstand external forces such as wind and snow during installation and long-term use.
- Elasticity and Flexibility: In addition to high strength, EVA film has a certain degree of elasticity and flexibility, which helps absorb impacts and deformations under stress, reducing damage to the solar cells.
These properties make EVA film perform excellently in various photovoltaic modules, especially in scenarios requiring frequent transportation and installation, providing reliable mechanical protection.
3. Superior Electrical Strength
The electrical performance of EVA encapsulation film is also a key consideration in solar encapsulation. It offers the following advantages:
- High Electrical Strength: EVA film has a high electrical strength, allowing it to withstand high voltages without electrical breakdown. This is crucial for ensuring the safety of solar cells operating under high-voltage conditions.
- Excellent Electrical Insulation: Due to its high volume resistivity, EVA film effectively isolates electrical currents, preventing leakage and electrical faults. This provides essential protection for the efficient operation and electrical safety of the solar cells.
These electrical performance characteristics play a critical role in protecting solar cells from electrical breakdown and other electrical damages, ensuring the long-term stability and safety of the solar power system.
The use of EVA in the process of precautions and consequences
1. EVA adhesive film has a strong adsorption capacity, in the use of the process, pay attention to moisture and dust, and avoid contact with colored objects.
- If moisture absorption, will affect the bonding strength of EVA and glass and back sheet, the water will be vaporized as the temperature rises, will produce bubbles.
- If dust absorption will affect the component light transmission, it will lead to EVA and the glass, the back of the bonding degradation, and even the bubble generation.
- If EVA and colorful, unclean objects are in contact, it is easy to be contaminated.
2. Do not expose the whole roll of EVA film to the air, and the film cut into pieces should be covered tightly if it cannot be used up on the same day.
- Do not touch the film directly with your hands. Oil or hand cream on hands will cause deterioration of EVA quality and poor bonding and discoloration.
- Avoid contact with water, oil, organic solvents, and pharmaceuticals. This can cause deterioration, poor bonding, and air bubbles.
- Can not be used in factories with open windows, garbage, and dusty places, which can cause EVA bonding to be low, and solar panels power shortage.
3. Storage environment for temperature below 30 degrees, and humidity below 60%.
Conclusion
EVA is an important part of solar modules. The long-term practice has proved: that it can obtain quite satisfactory results in both solar cell encapsulation and outdoor use.
Proper understanding and use of EVA, strict control of every aspect of the product, to produce high-quality products.
