"Why can glass generate electricity? Unveiling the production and preparation process of cadmium telluride photovoltaic modules—Part 4 in our Cadmium Telluride PV Series"

According to data from industry consulting firms, China's cadmium telluride (CdTe) industry reached a market size of approximately RMB 12 billion in 2023, representing a year-on-year growth of 15%. By 2025, the market is expected to expand further to RMB 16 billion, with an annual compound growth rate of around 14%. As a key technological approach in the photovoltaic sector, cadmium telluride thin-film solar cells are quietly gaining momentum in the BIPV (Building Integrated Photovoltaics) market, thanks to their unique material properties and manufacturing advantages. But how exactly is a complete CdTe power-generating glass module brought to life? This article will take you on an in-depth exploration of the precision manufacturing process behind CdTe photovoltaic modules, while also dissecting the intricate microstructure of the underlying solar cells.

1

Analysis of the Five-Layer Basic Structure

The Composition of Cadmium Telluride Thin-Film Solar Cells

Photovoltaic modules are the core components of photovoltaic power generation systems. Thin-film batteries have now evolved to include a variety of technological approaches, such as cadmium telluride (CdTe), copper indium gallium selenide (CIGS), gallium arsenide (GaAs), amorphous silicon thin films, and perovskites, among others. Cadmium telluride currently holds the largest market share among thin-film modules, accounting for more than 95% of the thin-film segment. 。 In recent years, p-type absorber layers for cadmium telluride thin-film solar cells have commonly employed alloyed materials, collectively referred to as CdTe-based absorber layers. , significantly boosting the current output of solar cells. Compared to other solar cells, cadmium telluride thin-film solar cells have a simpler structure; generally speaking, their basic architecture consists of five layers, namely Glass substrate, transparent conductive oxide layer (TCO layer), cadmium telluride (CdTe)-based absorber layer, back buffer layer, and back electrode 。

Glass substrate Typically, transparent conductive oxides (TCOs) are used as the front electrode to efficiently collect the battery's current, while at the same time The TCO film's high-transparency and anti-reflective properties also allow most light to enter the absorption layer. 。 Front Buffer Layer We must ensure that sunlight can enter the battery interior unimpeded, while also enhancing the interfacial performance between the absorption layer and the TCO to efficiently transmit and collect electrons. It can effectively block the disordered movement of electrons, reducing reactive power loss. Thus enhancing conversion efficiency. CdTe-based absorber layer Responsible for "eating to generate power," it is the battery's thickest core layer. As the light-absorbing layer, it converts photons into electron-hole pairs. These charge carriers separate under the influence of an electric field, generating an electric current and thus completing the conversion of light energy into electrical energy. Back Buffer Layer Doped semiconductor materials are often used to collect current and complete the circuit. Back electrode layer Responsible for transporting the collected holes outward, thereby completing the current output.

2

Manufacturing Process

From glass to power-generating components: the transformation

From an ordinary piece of glass to a photovoltaic module capable of generating electricity, the manufacturing of cadmium telluride modules is a complex process—almost like a sophisticated "alchemy." It involves a series of critical steps, each one essential to the final product: this "power-generating glass." The preparation process primarily consists of the following four key stages: Glass Substrate Pre-treatment : For the glass serving as the substrate, we need After rigorous cleaning through multiple steps, including reagents and ultrasonic treatment , to maintain the cleanliness of the glass surface. Meanwhile All four edges and corners are polished to relieve stress. , ensuring the adhesion and uniformity of the subsequent coating. Membrane Layer Preparation : This is the core manufacturing step for cadmium telluride solar cells. On commercially available TCO substrates with a front buffer layer, the CdTe-based light-absorbing layer is deposited, This step typically employs techniques such as CSS near-space sublimation (led by China's Longyan Energy) and vapor-phase transport deposition (represented by U.S.-based First Solar), among others. Following this, the film layer undergoes annealing treatment to further enhance battery performance. The deposition quality of the CdTe thin-film layer directly determines the battery's power-generation efficiency; therefore, This step requires precise control over parameters such as deposition temperature, gas pressure, and film thickness. , in order to ensure the battery's conversion efficiency. Laser Engraving : Producing a complete cadmium telluride power-generating substrate requires at least several laser scribing steps. By carefully cutting through the various film layers in a step-by-step process, Achieve the goal of dividing the film layer into multiple sub-cells, establishing positive and negative electrode connections among the internal sub-cells, and ensuring overall insulation of the module. 。 Product Packaging Once all functional layers are completed, the components need to be "protected." After laying the leads, The battery cells are securely bonded together with materials such as EVA film and backsheet glass through a lamination process. , providing moisture resistance and insulation while enhancing the weather durability of the components. The manufacturing process for cadmium telluride modules is a precise and intricate procedure that, in addition to the steps mentioned above, also includes edge trimming, junction box welding, high-voltage testing, IV testing, and other critical stages.

3

Industry Chain Landscape

The Short-Chain Advantage of Domestically Produced Cadmium Telluride

Compared to the crystalline silicon industry chain, the cadmium telluride industry chain is significantly shorter. The crystalline silicon chain—from upstream polysilicon materials, through midstream silicon wafers and solar cells, to downstream photovoltaic modules—relies heavily on extensive production equipment, supporting infrastructure, and substantial capital investment at each stage. Cadmium telluride module manufacturing demonstrates highly intensive production characteristics. Take Longyan Energy's next-generation, ultra-large-size cadmium telluride module production line as an example, A fully automated production line spanning 1,300 meters can handle the entire process chain—from pre-treatment of photovoltaic glass (including edge grinding and cleaning)—to cadmium telluride thin-film deposition, and finally to module integration and finished-product testing. Longyan, leveraging its deep expertise in cadmium telluride photovoltaics, has successfully established a highly representative industrial chain. Not only has it independently mastered the core technologies and key intellectual property rights for cadmium telluride thin-film solar cells and their supporting production equipment, but it has also achieved full domestic production across all manufacturing stages of the supply chain, effectively eliminating supply-chain vulnerabilities that could lead to "bottleneck" risks.

It is understood that currently, Longyan's large-size cadmium telluride modules have achieved production costs per watt that are virtually on par with mainstream crystalline silicon modules. As the cadmium telluride component industry expands in scale, production processes continue to be optimized, and manufacturing equipment gradually standardized, the cost of its production lines is expected to decline further. Consequently, whether measured by initial equipment investment or energy consumption during the production process, the cadmium telluride photovoltaic industrial chain demonstrates significant advantages. Cadmium telluride thin-film battery technology, with its unique industry-wide synergy and sophisticated manufacturing processes, has successfully transformed ordinary glass into highly efficient solar power generation modules. At its core lies the ability to deeply refine basic raw materials and then leverage cutting-edge thin-film deposition and laser processing techniques to create well-defined, functionally optimized power-generating units—ultimately assembling them into versatile photovoltaic components suited for a wide range of applications. Looking ahead, cadmium telluride thin-film solar cell technology is steadily advancing toward higher efficiency, lower costs, and broader adoption. This silent yet powerful green force is poised to play an increasingly vital role in shaping the future energy landscape.