Material structure of photovoltaic modules

With the deep adjustment of the world’s energy structure, the global step into the decarbonization cycle. Global energy is accelerating the transition to the direction of high efficiency, clean and diversified.

The development of clean energy has become an important factor affecting the global economy and ecological environment. Photovoltaic solar energy is clean, low-carbon, and environmentally friendly. And most efficient green energy, photovoltaic solar energy accelerates the transformation of the main energy. Photovoltaic packaging materials play a vital role in improving and ensuring the quality of photovoltaic modules. Especially on the photovoltaic module power generation efficiency, power stability, and reliability. And other aspects have an important impact. The promotion of standardization of PV packaging materials plays a supporting and leading role in R&D design, manufacturing, quality control, and supply chain management, and also promotes the development of the whole industry.

Photovoltaic packaging materials and their applications

PV encapsulation materials mainly include EVA (ethylene vinyl acetate copolymer encapsulation film), POE (polyolefin encapsulation film), PVB (polyvinyl butyral encapsulation film) encapsulation film. Photovoltaic encapsulation film is placed between the glass and solar cell or backsheet and solar cell of PV module. It is used to encapsulate and protect the solar cell and is one of the key materials of PV modules. And its main functions include bonding and structural support for PV module materials; high light transmission and maximum light coupling for solar cells; physical isolation and electrical insulation and water vapor barrier for PV modules; thermal conductivity and excellent weather resistance for PV modules.

Due to the structure of photovoltaic modules, the use of scenarios and solar cell technology routes is very different. The selection and application of photovoltaic packaging materials are also different.

Photovoltaic packaging materials of packaging film classification

As an important encapsulation material for PV modules, PV encapsulation film, with the demand of the market and the iteration of technology, has been derived from materials with different characteristics and meeting various usage needs. Since there is no unified and clear classification method for PV encapsulation film, through incomplete statistics of the mass-produced products on the market, it is divided into six categories according to its color, structure, pattern, material, process, and cross-linking method, and its characteristics are introduced respectively.

EVA film:

EVA resin is the main raw material, modified by adding cross-linking agent, silane coupling agent, light stabilizer, antioxidant, UV absorber, and other additives, melt processing, and molding of the adhesive film. It has excellent light transmittance and a wide process window, while EVA resin and additives are polar materials with good compatibility and absorption effect.

POE film: 

POE resin is the main raw material, modified by adding cross-linking agent, silane coupling agent, light stabilizer, antioxidant, UV absorber, and other additives, and then melt-processed into a film. It has an excellent water vapor barrier and PID resistance, but POE is a non-polar resin, so it is easy to cause the precipitation of additives.

PVB film:

PVB resin is the main raw material, modified by adding plasticizer, silane coupling agent, light stabilizer, antioxidant, UV absorber, and other additives, melt processing, and molding of the film. It has excellent mechanical strength.

EPE adhesive film:

EVA and POE co-extruded melt processing molding adhesive film.

Transparent adhesive film:

Including high-transmittance type and UV cut-off type. High-transmittance type can transmit the full wavelength of sunlight to maximize the conversion efficiency of solar energy. UV cut-off type has the ability to absorb UV rays, which can effectively improve the aging of materials caused by UV rays.

White adhesive film:

Including the non-woven composite structure and pre-cross-linked white film, mainly through titanium dioxide coloring. Non-woven composite structure white film has a good buffering effect, anti-overflow glue effect, and zero depth reflection to enhance power gain. Pre-cross-linked white film is adjusted by the initial cross-linking degree to control the overflow of glue turning white, wrinkling, and good reflectivity.

Single-layer structural adhesive film:

Refers to pure EVA, POE, PVB adhesive film.

Multi-layer composite structural adhesive film:

Refers to EVA, POE and non-woven composite white film, and EPE co-extruded adhesive film.

Frosted film:

The frosted film with an irregular pattern on both sides is anti-adhesive and anti-slip.

Prismatic film:

Steel roller surface is a regular prismatic pattern film, anti-adhesive, non-slip, and applicable to high grammage film.

Casting film:

The film is processed and shaped by the way of casting, currently, the PV encapsulation film is mainly processed and shaped by the casting process. Cast film has better flexibility, greater fluidity, less internal stress, and a low shrinkage rate.

Photovoltaic ribbon, also known as tinned copper tape or tinned copper flat wire. It is divided into a sink tape and an interconnection strip, which is used for the connection of thousands of photovoltaic module cells. Welding tape is an important raw material in the welding process of PV modules.

Photovoltaic ribbon is a hot-dip tinned copper conductor that collects current from photovoltaic cells.

Raytron provides oxygen-free copper ( Min 100%IACS) and copper-clad aluminum ( Min 60%IACS) flat wire in a variety burr-free edges such as Square, Natural Round, and Full Round. Yield strength could be reach ＜70Mpa.