How are silicon plaques made?
From the life of a photovoltaic service technician – How are silicon plates for photovoltaic panels made?
Photovoltaics is a technology that converts sunlight into electricity using the photovoltaic phenomenon. A key component of this process is photovoltaic panels, which are made of many interconnected photovoltaic cells made of semiconductors. Among the various semiconductor materials, silicon (Si) is the most popular, providing the basis for about 90% of the world’s solar panels. The manufacturing process of silicon arrays, which are the basis of photovoltaic cells, is multi-step and technologically complex. Manufacturing topics are definitely of my greatest interest. So today we will take an in-depth look at how silicon arrays are made. From the extraction of the raw material, to its processing, to the finished product that goes to the panel manufacturers.
1. extraction of raw silicon. How are silicon plaques made?
Silicon is one of the most abundant elements in the Earth’s crust, accounting for about 28% of its mass. The raw material used to produce high-purity silicon is quartz (SiO2). It is mined in sandstone mines and other rock formations. Quartz contains silicon in the form of silicon oxide, which must be converted into pure metallurgical silicon.
The quartz reduction process takes place in arc furnaces, where silica (SiO2) reacts with carbon at very high temperatures (above 2000°C). This, in turn, leads to the precipitation of pure silicon and carbon monoxide:
SiO2+2C→Si+2CO
The resulting metallurgical silicon has a purity of about 98-99%. It is a raw material that must undergo further purification processes to make it suitable for electronics and photovoltaic applications.
2. purification of silicon for solar grade
Very high-purity silicon (so-called solar silicon), containing only 1 impurity atom per billion silicon atoms (99.9999% purity), is required for the production of photovoltaic panels. The purification of silicon is carried out through a halogen chemical reduction method, which produces silicon tetrachloride (SiCl4). In the next step, silicon tetrachloride is subjected to a fractional distillation process, followed by hydrogen reduction to polycrystalline silicon:
SiCl4+2H2→Si+4HCl
After this process,Solar Grade Silicon (SGS) is obtained. It is ready for further processing toward the production of monocrystalline or polycrystalline silicon.
3. Czochralski method: growth of silicon monocrystals
One of the most widely used methods for producing monocrystalline silicon plaques is the Jan Czochralski method. It was invented by Polish scientist Jan Czochralski in 1916. It has been written about many times but you can also listen to our YouTube podcast about it.
How are silicon plaques made? The process involves the growth of a single crystal of silicon from molten raw material.
Process steps:
- Silicon melting: Solar-grade silicon is heated to temperatures above 1420°C in a quartz crucible until it is completely melted.
- Crystal nucleation: A monocrystalline silicon embryo is introduced into the molten silicon. This embryo is slowly pulled upward while rotating around its axis.
- Crystal growth: As the embryo is drawn out, silicon atoms from the molten raw material crystallize around it, forming an increasingly large monocrystal with a specific structure. This process is precisely controlled to produce a crystal with a homogeneous structure.
This produces a silicon monocrystal in the form of a cylinder with a diameter of 150 to 300 mm and a length of up to 2 meters.
4 Cutting and forming silicon plaques. How are silicon plaques formed?
Silicon monocrystals obtained by the Czochralski method are then cut into appropriate pieces. The first step is to cut the silicon cylinder into flat segments. For this purpose, wire saws are used, which can precisely cut hard silicon into very thin wafers. The thickness of silicon wafers, which are used in solar panels, is usually between 160 and 200 micrometers.
To increase cutting efficiency, advanced methods such as diamond saws are often used. After cutting, each silicon wafer undergoes chemical and mechanical pre-treatment to remove any surface irregularities and defects. The cutting process also produces waste in the form of silicon dust, which is often recycled and reused in production.
5. etching and surface cleaning
Cutting of silicon wafers is followed by a chemical etching process to further clean the surface and give it the right structural properties. Etching is carried out in chemical baths, most often in solutions of hydrofluoric acid (HF) and nitric acid (HNO3), which effectively remove impurities and smooth the surface of the wafers. In some cases, special textures are added to the surface of the wafers to improve the ability to absorb sunlight, which increases the efficiency of photovoltaic cells.
6. packaging and transportation of silicon plaques
The finished silicon wafers are then carefully inspected for defects and impurities. Each plate must meet strict quality standards to be used in the production of photovoltaic cells. The wafers are then packed in specially designed containers that protect them from mechanical damage and contamination during transportation. The protected silicon wafers are sent to factories where they will be transformed into finished solar cells.
How are silicon plaques made? The process of manufacturing silicon wafers for photovoltaic panels is an advanced and multi-step procedure, involving both the extraction of raw silicon and the complex processes of purification, monocrystalline growth, cutting, etching and transportation of finished wafers.
Each step requires precise quality control so that the final product can meet the efficiency and durability requirements crucial in the photovoltaic industry. Developed technologies, such as the Czochralski method, allow the production of monocrystalline silicon arrays that form the basis of today’s solar cells, contributing to the sustainable development of renewable energy.
If you notice any problems with your photovoltaic installation, don’t delay – contact an experienced service technician who will help you quickly and effectively solve the problem. When do you need a photovoltaic service technician?
Are you planning to build your photovoltaic farm or looking for an O&M service company?
Do you want to purchase a photovoltaic or wind farm project and need an efficient and professional audit / due diligence?
are you looking for a photovoltaic panel recycler or cleaning company for photovoltaic plants and farms?
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