The manufacturing process of photovoltaic cells involves complex engineering techniques, and the manufacturing process of different photovoltaic technologies (such as crystalline silicon, thin films, etc.) Here's a brief overview of the manufacturing process for crystalline silicon photovoltaic cells, the most common type of photovoltaic cell:
Purifying silicon raw materials: Silicon is the most commonly used semiconductor material in photovoltaic cells. First of all, the silicon feedstock needs to be purified to achieve the purity required for photovoltaic cells. This is usually achieved by chemical vapor deposition (CVD) to produce polysilicon.
Production of silicon ingots: The purified polysilicon is melted and solidified at a certain temperature to form silicon ingots. This process can be done by either the Czochralski process (CZ method) or the Float Zone (FZ method). The CZ method involves immersing an elongated monocrystalline silicon seed crystal into molten silicon, and then slowly lifting and rotating it to solidify the silicon on the seed crystal to form a large monocrystalline silicon ingot. The FZ rule is to gradually solidify silicon into a single crystal by moving the heating area on the silicon raw material rod.
Cutting silicon ingots: Silicon ingots are cut into thin slices, i.e., silicon wafers. These wafers are typically between 150 and 200 microns thick. Cutting can use a multi-wire cutting machine, which uses a fine wire (usually steel or diamond wire) to cut silicon ingots.
Cleaning and polishing of silicon wafers: Cut silicon wafers need to be cleaned and polished to remove impurities and damage on the surface and ensure a smooth surface to improve photoelectric conversion efficiency.
Fabrication of photovoltaic cell structure: Silicon wafers undergo a series of processing to form the structure of photovoltaic cells. This includes applying an anti-reflective coating to the wafer to reduce light reflection loss, as well as forming a PN junction on the wafer through diffusion, ion implantation, etc., which is a key part of the photoelectric conversion of photovoltaic cells.
Electrode fabrication: Electrodes are made on the surface of a silicon wafer, usually by coating the front side of the silicon wafer with a layer of conductive material (such as aluminum or silver paste) and then fixing it through a sintering process. On the back of the silicon wafer, electrodes are also made to facilitate the output of electric current.
Encapsulation: Manufactured individual photovoltaic cells are assembled into photovoltaic modules. These batteries are connected in series or parallel to produce the required voltage and current. The battery is then encapsulated between the glass and the backplate to protect the battery from environmental factors.
Testing and certification: Finally, PV modules need to undergo rigorous testing and certification to ensure that their performance meets standards and expectations. Testing involves checking the battery's current, voltage, power output, and durability.