The term EVA refers to ethylene-vinyl acetate. EVA films are a crucial component in the manufacturing of traditional solar panel lamination and, more recently, solar PV modules.

The main purpose of using EVA film is to adhere the solar cell to the substrate (e.g. glass).

The chemical structure of EVA consists of long carbon chains with vinyl acetate monomers attached at random intervals along the chain.

The degree of vinyl acetate (VA) content in the copolymer determines the melting point, flexibility, and optical properties of the EVA.

Films with a higher VA content are more flexible and have a lower melting point, while those with a lower VA content are less flexible and have a higher melting point.

What Are Ethylene Vinyl Acetate (Eva) Films?

Ethylene-vinyl acetate, often known as EVA, is a copolymer consisting of ethylene and vinyl acetate. It’s a soft, flexible, and non-toxic composite that has a variety of uses.

The most common use for EVA film is as an interlayer in solar PV modules. The film is placed between the solar cell and the front glass to protect the cell from mechanical damage and moisture.

EVA film is also used in the manufacturing of hot melt adhesives, drug delivery devices, and laminates.

Long-Term Encapsulation And Protection

The ethylene-vinyl acetate sheets, which have been laminated over the EVA sheets, play an essential part in preventing humidity and debris from entering the solar panels.

The solar cells also “float” between the glass and back sheet, reducing shocks and vibrations that might otherwise harm them.

Ethylene-vinyl acetate (EVA) properties:

Durability

Quality EVA film is known for its excellent durability, also in difficult weather circumstances, such as high temperature and high humidity.

The material can also withstand repeated bending without losing its shape.

This makes it an ideal material for solar panels, as they are often exposed to the elements.

Bonding

Under the right conditions, EVA film has excellent adhesion to solar glass (not ordinary glass; solar glass has a rough surface).

Also, EVA is quite adhesive to the back sheet of a solar panel. This is critical since it ensures that the panel will not fall apart over time.

EVA also has good bonding with other materials used in the solar industry, such as Tedlar (PVF) and TPT.

Water Resistance

Another important property of EVA film is its water-resistant nature. This is essential in protecting the solar cells from moisture, which can cause corrosion.

EVA film is also used as an adhesive in the lamination of photovoltaic (PV) modules. It is applied between the solar cell and the front glass to protect the cell from mechanical damage and moisture.

EVA films are available in a variety of thicknesses, ranging from 0.5 mil (12.7 microns) to 10 mil (254 microns).

The most common use for EVA film is as an interlayer in solar PV modules. The film is placed between the solar cell and the front glass to protect the cell from mechanical damage and moisture.

Optical

The material’s outstanding transparency has earned it the name “Solar EV.”

This means that the optical transmission is adequate and does not obstruct too much of the sun’s rays when attempting to reach the solar cells.

Many manufacturers in Asia presently utilize a transparent backing, which has transparency between cells as a result.

The term “semi-transparent” refers to a film that is more like an opal, with a milky white appearance.

Thermal

EVA has good heat resistance, meaning it can withstand high temperatures without deforming.

This is essential in the lamination process, where temperatures can reach 200 degrees Celsius (392 degrees Fahrenheit).

The material’s thermal conductivity is another important factor to consider. A low thermal conductivity ensures that heat is not transferred too quickly, which can cause the solar cells to break.

EVA’s coefficient of thermal expansion (CTE) is also an important factor. This measures how much a material expands or contracts when exposed to heat.

A lower CTE means that the material will expand less, which is ideal in a solar panel.

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