Structure of Solar Panels: 6 Key Components

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Key Elements of a Solar Panel

Solar panels, fundamental to the technology of solar energy, consist of various key components, each playing a significant role in capturing sunlight and transforming it into electrical power. This article aims to delve into the vital elements that constitute a solar panel, exploring the importance of each component in its functionality and effectiveness. Ranging from the protective surface glass to the essential junction box for electrical connectivity, every part is integral to the solar panel's overall performance. Join us as we navigate through the details of solar panel construction and understand the complexities behind their design!

Content:

  1. Solar Panel Glass
  2. Solar Panel Encapsulation Film
  3. Solar Cell
  4. Solar Panel Backsheet/Back glass
  5. Solar Panel Frame
  6. Solar Panel Junction Box(J-Box)

Solar Panel Glass

In the realm of solar panels, the role of photovoltaic glass is crucial. It acts as an essential barrier, protecting the solar cells and soldering ribbons from environmental adversities such as impacts, hail, moisture, salt mist, and ammonia. Its functionality extends beyond protection, playing a key role in enhancing light collection, transmission, and reducing light reflection, thereby optimizing electricity generation.

Key Features and Uses of Photovoltaic Glass:

Superior Light Transmission: Photovoltaic glass is distinguished by its high light transmittance. While standard tempered glass permits around 91.5% of light to pass through, advanced treatments (like coated glass) can increase this to about 93.5%. This higher light penetration directly benefits the solar cells, leading to greater energy conversion efficiency in the solar panels.

Extensive Spectrum Absorption: This glass is adept at absorbing light across a spectrum from 380 to 1100 nanometers, effectively tapping into the primary energy bands of sunlight. It also reflects infrared rays (with wavelengths beyond 1200 nanometers), which helps in minimizing heat absorption and preventing the rise in temperature that could affect panel efficiency.

Enhanced Impact Resistance: Photovoltaic glass is known for its strong resistance to impacts. For example, a 3.2mm fully tempered glass can withstand the impact of a 1kg steel ball dropped from 1 meter and can resist hailstones up to 2.5mm in diameter. This ensures the durability and reliability of solar panels in extreme weather conditions.

Glass Types and Thicknesses for Various Solar Panels:

Mono-Glass Solar Panels: These typically use 3.2mm fully tempered glass, backed by a rear sheet.

Dual-Glass Solar Panels: These panels generally incorporate 2.0mm or 1.6mm semi-tempered glass on both the front and rear. Semi-tempered glass, which sits between standard flat glass and fully tempered glass in terms of impact resistance and thermal tolerance, offers advantages in the manufacturing process of dual-glass solar panels, improving both yield and quality.

Glass Types and Thicknesses for Various Solar Panels:

Solar Panel Encapsulation Film

Encapsulation films, commonly referred to as solar panel encapsulants, are integral to the structure of solar panels. Situated between the front glass and the rear backsheet, these films are crucial for the stability and protection of the solar cells. They not only secure the cells in place but also offer vital insulation and waterproofing, safeguarding the panels from various environmental factors.

Solar Panel Encapsulation Film Encapsulation films, commonly referred to as solar panel encapsulants, are integral to the structure of solar panels. Situated between the front glass and the rear backsheet, these films are crucial for the stability and protection of the solar cells. They not only secure the cells in place but also offer vital insulation and waterproofing, safeguarding the panels from various environmental factors.

Key Functions and Features of Encapsulation Films:

Protection of Solar Cells: Encapsulation films are pivotal in stabilizing solar cells, preventing their movement or breakage. This ensures the structural integrity and long-term efficiency of the solar panel.

Transparency and Weather Resistance: High-grade encapsulation films are characterized by their exceptional transparency, which is crucial for minimizing solar energy loss. They are also designed to be weather-resistant, capable of enduring UV rays, high temperatures, and other challenging environmental conditions.

Insulation and Waterproofing: These films play a significant role in insulating the panel. They prevent moisture and other environmental elements from infiltrating, thereby protecting the solar cells from corrosion and damage.

Durability: The material of the encapsulation film is selected for its ability to withstand prolonged exposure to sunlight and varying climatic conditions, ensuring consistent performance over time.

Common Types of Encapsulation Films:

EVA Film: Predominantly used in encapsulating mono-crystalline P-type Perc modules, EVA films are made from ethylene-vinyl acetate copolymer, primarily consisting of acetic acid ethenyl ester (40-70%). Their advantages include cost-effectiveness, ease of processing, quick cross-linking, and a well-established, stable application process. However, EVA is susceptible to hydrolysis in environments with light, oxygen, and humidity, leading to acetic acid production that can corrode solar cells and solder ribbons. It also reacts with sodium in glass, generating a significant amount of mobile sodium ions, which can cause power attenuation. Additionally, EVA tends to yellow under photothermal conditions, impacting transparency and leading to power loss in the module.

POE Film: Commonly used in encapsulating dual-glass and N-type photovoltaic modules, POE films, made from a type of polyethylene, exhibit superior characteristics compared to EVA. These include low water permeability, resistance to hydrolysis, high-temperature and humidity resistance, aging resistance, excellent PID resistance, high electrical resistivity, and outstanding water vapor barrier properties. The downsides are its more complex processing requirements and higher cost relative to EVA.

EPE Film: This is a composite film consisting of EVA+POE+EVA layers. EPE combines the processing ease of EVA with the excellent PID and water vapor resistance properties of POE. It is particularly suitable for N-type Topcon solar cells and dual-glass modules, offering a balanced cost-performance ratio.

Solar Cell

Solar cells are the fundamental components that convert sunlight into electricity, serving as the core of solar panels. The efficiency and characteristics of these cells depend largely on the type of semiconductor material utilized.

Main Types of Solar Cells: P-type and N-type

P-type Solar Cells:

Manufacturing Process: P-type solar cells are produced by doping basic semiconductor materials, such as silicon, with trivalent elements (e.g., boron). This doping process introduces positively charged 'holes' (regions lacking electrons) into the semiconductor.

Functionality: In the presence of an electric field, these 'holes' become the primary carriers of electric charge, facilitating the creation of an electric current.

Usage and Popularity: P-type materials are widely used in the production of multicrystalline silicon solar cells and some monocrystalline silicon solar cells. Their popularity stems from their cost-effectiveness and the simplicity of the manufacturing process.

P-type Solar Cells:

N-type Solar Cells:

Manufacturing Process: N-type solar cells are created by doping silicon with pentavalent elements, such as phosphorus. This process adds additional valence electrons to the material, enhancing its electrical conductivity.

Functionality: In the presence of an electric field, these extra electrons act as the primary charge carriers, resulting in the generation of an electric current.

Advantages and Applications: N-type materials are gaining increasing significance in the realm of high-efficiency solar cell technologies, such as TOPCon (Tunnel Oxide Passivated Contact), IBC (Interdigitated Back Contact), and HJT (Heterojunction). This is due to their stability over time and superior performance characteristics.

P-type Solar Cells or N-type Solar Cells: What Technology to Choose?

Most Common Types of Solar Cells on the Market:

The solar cell industry is rapidly advancing, with N-type materials receiving considerable attention for their high efficiency. Notable developments include:

HJT (Heterojunction) Solar Cells: These cells merge the advantages of crystalline and amorphous silicon. By placing an amorphous silicon layer between N-type and P-type silicon, HJT cells enhance stability and efficiency. This arrangement prevents the recombination of electrons and holes.

TOPCon Technology: TOPCon cells utilize tunnel oxide layers and polycrystalline silicon layers as electrodes, significantly improving overall cell performance.

IBC (Interdigitated Back Contact) Cells: These cells are designed with all electrodes on the back, maximizing light absorption and reducing shading effects.

As technology evolves and costs decrease, N-type solar cells are expected to become increasingly prominent in the future solar energy market. However, P-type cells will maintain their widespread use due to their established market presence and well-developed manufacturing processes. These advancements are not only enhancing the efficiency of solar cells in converting light into electricity but also paving the way for more sustainable and environmentally friendly energy solutions.

Solar Panel Backsheet / Back Glass:

The backsheet is a crucial component in solar panels, primarily used in outdoor environments. It plays a vital role in protecting the solar cell module from various environmental factors like light, humidity, heat, and cold, which can affect the encapsulation film, cells, and other materials. The quality of the backsheet is a key determinant of the module's lifespan.

Details on Backsheets:

Variety in Appearance: Backsheets are available in different colors, such as white, black, and transparent. White backsheets reflect sunlight back onto the solar cells, enhancing energy efficiency. Black backsheets are popular in Europe and America for their aesthetic appeal in rooftop installations. Transparent backsheets allow solar panels to generate electricity from both sides.

Material Composition: Backsheets typically comprise three layers: an outer layer, a middle PET substrate, and an inner layer. Materials like fluorine and PVDF films are used to ensure protection against UV radiation and durability.

Performance Compatibility: Engineered to be compatible with various solar cell types, including Perc, N-type, and TOPCon cells, backsheets have low water permeability, which is essential for maintaining cell efficiency and longevity. This ensures that solar panels remain effective over a long period.

Details on Backsheets:

Back Glass:

Back glass, available in thicknesses of 2.0mm and 1.6mm, is increasingly favored for its outstanding durability and ability to withstand various environmental conditions.

Advantages and Applications of Back Glass:

Moisture Barrier: One of the key features of back glass is its near-zero moisture permeability. This makes it exceptionally suitable for high-humidity environments, as it effectively prevents water-induced damage to the solar panels.

Resilience and Longevity: The high resistance of back glass to wear, weathering, and corrosion renders it ideal for use under extreme conditions. This resilience significantly contributes to the extended lifespan of solar panels.

Fire Safety: Solar panels that incorporate rear glass are known for their high fire resistance. This attribute makes them a safer option for both residential and industrial installations.

Insulation Properties: The excellent insulation properties of rear glass allow solar panels to operate at higher system voltages. This can be particularly advantageous in large solar power stations, offering cost-effective solutions.

The integration of back glass into solar panel designs not only enhances their durability and safety but also improves their overall performance. This makes them more reliable and efficient in the generation of clean energy. For more detailed information about solar panel backsheets, consider reading the related article.

Back Glass