Solar cell laser processing deserves attention

Laser processing is a relatively emerging non-contact processing method that utilizes the high energy of a beam of light to interact with materials and instantly vaporize or change their properties to achieve the expected manufacturing effect. It has gradually been promoted and applied in China in the past 20 years. Due to the different types, pulse widths, and wavelengths of laser generators, their applicability is wide, and there are many scenarios, the utilization rate of laser processing has not been fully explored to this day.

Laser processing mainly includes processes such as marking, cutting, welding, cladding, cleaning, etc. Currently, the main application share of industrial laser in China is in metal cutting and welding, which is a rough machining method. The requirements for workpiece accuracy are not very high, and the universality of equipment is strong, so it is easy to form a batch scale. Another aspect of laser application is precision machining. Due to the fact that most of it is customized processing, the equipment also depends on the properties of the materials, sometimes wafers, sometimes glass, PCB boards, or thin films or synthetic materials. The products are small and precise, and the laser process development and sample cycle are long, making precision laser machining difficult to mass produce.

In precision laser processing, it also includes industry applications such as mobile phone component processing, display screen or OLED cutting, glass cutting, etc. It is worth noting that laser processing on solar cells is rapidly being promoted in recent years.

1. Demand for laser processing of solar cells
Recently, Haimu Star announced the establishment of a photovoltaic technology subsidiary in Jiangsu. Coincidentally, Inno Laser also announced the expansion of its Changzhou subsidiary to support the development of photovoltaic business. Ruike stated that its products have been applied to photovoltaic cutting equipment. Han's photovoltaic equipment company was established as early as 2018. It can be seen that leading enterprises in the laser industry have laid out their photovoltaic product market one after another.

In fact, the process and equipment for laser companies to layout solar cells have already existed. Around 2010, companies such as Suzhou Delong and Wuhan Sangong launched laser slicing machines, but they did not receive large-scale promotion and application at that time, and some companies gradually withdrew from this market. Solar cells have once again caught the attention of laser industry professionals. Six or seven years ago, Wuhan Deere Laser made several breakthroughs in the solar cell industry, with an average annual growth rate doubling and becoming the industry's dark horse. Deere Laser quickly entered the solar cell industry with laser slotting equipment used in PERC batteries.

A few years ago, when it comes to the new energy industry, people always thought of lithium-ion batteries/electric vehicles. In fact, solar energy also belongs to the new energy sector. Some companies that laid out solar energy early have now tasted the rewards:
Haimu Star launched photovoltaic laser and automation equipment, including TOPCon primary doping equipment, in 2022. It was mass-produced this year, with equipment orders exceeding 400 million yuan.

The TOPCon laser SE direct mixing equipment of Inno Company has been recognized by multiple important customers in multiple key indicators such as efficiency improvement, production capacity, and fragmentation rate. In 2023, nearly 20GW of contracts have been signed.

Han's Photovoltaic Equipment Company achieved a revenue of 98 million yuan in the first half of the year, a year-on-year increase of 46.96%, making it the segment business with the highest year-on-year growth rate for Han's Laser. At present, there are still orders worth 430 million yuan in hand for the photovoltaic equipment business.

In 2023, with weak industrial economic growth and intensified internal competition in the laser industry, the demand for laser processing equipment for solar cells is gradually increasing, becoming a major growth highlight.

2. Where is laser used for solar cells
The production process of solar cells involves many processes, and the role of lasers may be just one or two important steps. At present, PERC batteries occupy the mainstream in China, requiring laser slotting of battery cells to penetrate the passivation film on the back without causing significant damage to the silicon wafers. This exposes the entire silicon substrate clearly, making it flat and smooth without obvious laser pulse corrosion marks, thereby providing power generation conversion efficiency for the battery cells.

SE laser doping is a core process in the production of solar cells, which is a technology that uses laser radiation to change material properties. Doped atoms can be introduced on the surface or inside the material to form heavily doped regions and improve photoelectric conversion efficiency. In the SE process of PERC (P-type battery), boron is added, while in the SE process of TOPCON (N-type battery), phosphorus is added.

On the BC battery process line, laser slotting technology and component laser welding technology can be used. In the TOPCon battery process, laser induced sintering, laser boron doping, laser film opening and other processes can be used. The manufacturing process of BC battery is complex and difficult, requiring higher precision of laser.

Source: Teyu Electromechanical