Photovoltaic cells are classified by substrate material and can be divided into P- and N-type batteries. A P-type battery refers to a battery with a P-type silicon wafer as the substrate, and an N-type battery refers to a battery with an N-type silicon wafer as the substrate. P-type silicon wafers have a simple production process and low cost, while N-type silicon wafers usually have a long life and can do higher battery efficiency, but the process is more complex. This is mainly because the N-type of silicon-doped phosphorus element, phosphorus, and silicon miscibility is poor, and easy to uneven distribution, and P-type silicon-doped boron element, boron, and silicon separation coefficient is equivalent, dispersion uniformity is easy to control, the cost is lower. Therefore, at present, the mainstream product of the photovoltaic industry is P-type silicon wafers, and the corresponding P-type batteries are more.

P-type batteries: Typical P-type batteries include BSF batteries, PERC batteries, PERC+ batteries, etc. Among these categories, they appear at different times, and the market's evaluation of them is different. The early photovoltaic power generation technology was based on BSF batteries, and then PERC battery technology began to replace BSF technology, and then PERC battery technology was optimized to form PERC+ technology.

1. BSF battery After the PN junction of crystalline silicon photovoltaic cells is manufactured, the P+ layer is prepared by depositing an aluminum film on the backlight surface of the silicon wafer, thus forming an aluminum backfield. Aluminum as the backfield has many advantages, such as reducing the surface coincidence rate and increasing the absorption of the long waves, but the photoelectric conversion efficiency of aluminum backfield batteries also has certain limitations. In terms of process, the preparation of a BSF battery must go through cleaning and fleecing, diffusion and bonding, etching de-phosphorized silicon glass, PECVD, screen printing, sintering, testing, and sorting. The BSF battery process is the general process for the preparation of photovoltaic cells, and then upgraded, which is based on this process.

2. PERC battery is based on the traditional BSF battery, adding the back passivation and laser start two processes, and the performance has been significantly improved. The corresponding application core equipment includes a cleaning machine, fleecing machine, diffusion furnace, laser ablation machine, etching machine, PECVD, screen printing equipment, sintering furnace, test and sorting machine, etc. A trough cleaning machine is also required if the back polishing process is added.

N-type battery: Although PERC batteries occupy the mainstream, the photoelectric conversion efficiency of N-type batteries is higher, even if the technical difficulty is large, but to reduce costs and increase efficiency, companies are accelerating research and development. N-type batteries include IBC, HJT, HBC, and TOPcon batteries. Among them, TOPcon and HJT are the main technical routes and have begun to expand production. IBC and HBC are still in the experimental and verification stage and are called "future technologies."

3.TOPcon battery TOPCon battery structure can achieve perfect passivation on the battery surface. It uses an ultra-thin oxide layer and is doped with thin-film silicon, both of which are efficient operations. Finally, the theoretical limit of the conversion efficiency can reach 26.6%. Compared with the PERC battery, the TOPCon process increases two links: boron diffusion and contact passivation layer deposition. A major link is the oxidation and deposition of type I polysilicon by LPCVD, which is divided into two sub-categories, one is the full diffusion process, and the other is the phosphorus process. Another big link is PECVD oxidation and deposition of P-type polysilicon, which is a shorter process and is expected to significantly reduce costs and is also the development direction of technology.

4. HJT battery HJT battery, also known as a heterojunction battery, is a hybrid solar cell and a double-sided battery. Compared with PERC batteries and TOPCon batteries, the process flow of HJT is greatly shortened, which helps to shorten production time and improve production efficiency. Its preparation process probably includes cleaning and milling, amorphous silicon deposition, TCO film preparation, and screen printing. Among them, amorphous silicon deposition and TCO film preparation are two key links, and there are two preparation methods. The amorphous silicon deposition method is PECVD or CAT-CVD. Compared with the former, the latter has a higher film-forming quality and a better passivation effect on silicon wafers, but its uniformity is poor and the maintenance cost is high. The method used to prepare the TCO membrane is PVD or RPD. The latter technology has low equipment production capacity and high price, and the patent is currently in the hands of Sumitomo, Japan, and has patent protection. Relatively speaking, the former PVD is more likely to become a mainstream process.

5. IBC battery IBC battery, also called an interfinger-type back contact battery, is one of the high-efficiency large-area solar cells and is also a typical N-type battery. Here the back contact batteries include MWT, EWT, and IBC batteries, the conversion efficiency of MWT and EWT batteries is limited to a certain extent, and the theoretical conversion efficiency of IBC batteries is higher. The front of the IBC battery has no metal gate line, and the components on the back are interfinger-like. This structure can increase the power generation area and improve the power generation efficiency. IBC batteries can also be integrated with HJT battery technology, that is, HJBC, and HBC battery technology, and the efficiency of both reached 25.1% and 25.6%, respectively.

With the gradual maturity of TOPCon, HJT, IBC, and other technologies, approaching the theoretical limit of their photoelectric conversion efficiency, the industry has begun to look for a new generation of photovoltaic technology. If the above are all crystalline silicon batteries, then according to another standard, there are thin film batteries.

Perovskite photovoltaic modules are one of them, which use perovskite-type metal halide semiconductors as light-absorbing layer materials to absorb photons generate electron pairs, and drive batteries. In the early days, perovskite was referred to as a metallic mineral. At present, perovskite generally refers to ionic crystals with the same or similar crystal structure as calcium titanate. As a photoelectric conversion material, it has the following advantages: first, the photoelectric conversion efficiency is very high, in the past ten years, the efficiency of perovskite cells has increased from 3% to 28%, and even laboratories can achieve 31.3% conversion, the growth rate is much higher than the development speed of silicon-based batteries, 13 years to complete the development of silicon-based batteries for 40 years. Second, the material manufacturing cost is low, and the synthesis method is simple. Third, it can achieve free regulation of the absorption band gap, thereby increasing the utilization efficiency of light energy, and even, the ultimate efficiency of the laminated battery is expected to exceed 40%. However, the current large-scale preparation of perovskite layer technology is not mature, and the stability of the material is insufficient, if you want to further industrialization, but also need to carry out more in-depth research on the performance and stability of the device.

In SUMMARY:

From the perspective of the current market competition pattern, because the process is in line with the mainstream Perc technology in the P-type era, TOPcon technology has naturally presented short-term high certainty, and from the perspective of SENC, it is a large probability and a large volume. The disruptive technology represented by HJT has many advantages in performance, but the production line, process, and Perc era are not connected, and large-scale production is not economical for mainstream battery manufacturers. As a platform-level technology, HJT is more smoothly integrated with the next-generation perovskite battery technology to form laminated batteries. At present, HJT and TOPCon technology in the battery manufacturing side has entered the actual battle stage, which of the two is better, the market voice is not unanimous. Overall, TOPcon technology has obvious short-term advantages, and HJT has greater potential in the future. The N-type battery technology path is clear, but whether it can be achieved and the pace of implementation is still uncertain, if the cost reduction is less than expected, it may make downstream manufacturers delay capital expenditure plans, which will affect the short-term performance of those equipment manufacturers. There are also different technical paths for different equipment demand compositions is different, technology iteration will affect the manufacturer's equipment demand, and thus also affect the performance of the manufacturer. In short, iteration makes technology continue to improve, and products continue to reduce costs and increase efficiency, but the corresponding manufacturers will also face a lot of risks.