Definition And Production of High Voltage Solar Battery

High Voltage solar battery has been developed many years ago. In many aspects of life, battery backup solar has brought us a lot of conveniences. We all know that one of the benefits of High Voltage solar batteries is environmental protection. To enhance everyone's understanding of High Voltage solar batteries, this article will introduce the production process of High Voltage solar batteries. If you are interested in High Voltage solar batteries, please continue reading.

• What is High Voltage solar battery?

• How to make High Voltage solar batteries?

What is High Voltage solar battery?

High Voltage solar battery is a device that directly converts light energy into electrical energy through the photoelectric effect or photochemical effect. The crystalline silicon High Voltage solar battery that works on the photovoltaic effect is mainstream, while the implementation of the High Voltage Lithium Battery on the thin film battery that works on the photochemical effect is still in its infancy.

How to make High Voltage solar batteries?

1. Wafer cutting, material preparation

The monocrystalline silicon material used in the industrial production of silicon cells generally adopts solar-grade monocrystalline silicon rods produced by the crucible Czochralski method. The original shape is cylindrical and then cut into square silicon wafers or polycrystalline square silicon wafers. The side length of the silicon wafer is generally 10~15cm, the thickness is about 200~350um, and the resistivity is about 1Ωcm p-type.

2. Remove the damaged layer

A large number of surface defects will be generated during the cutting process of silicon wafers, which will cause two problems. Firstly, the quality of the surface is poor. In addition, these surface defects can lead to increased debris during the battery manufacturing process. Therefore, to remove the cutting damage layer, alkali or acid corrosion is generally used, and the thickness of the corrosion is about 10um.

3. Texturing

Texturing is to corrode the surface of the relatively smooth raw material silicon wafer with acid or alkali to make it uneven and rough, forming diffuse reflection and reducing the loss of solar energy that directly hits the surface of the silicon wafer. For monocrystalline silicon, the method of NaOH plus alcohol is generally used for etching, and the anisotropic etching of single-crystal silicon is used to form countless pyramid structures on the surface. The temperature of the lye is about 80 degrees, the concentration is about 1-2%, and the corrosion time is about 15 minutes. For polycrystalline, acid etching is generally used.

4. Diffusion knot

The purpose of diffusion is to form a PN junction. Phosphorus is generally used for n-type doping. Since solid-state diffusion requires a high temperature, it is very important to clean the surface of the silicon wafer before diffusion. It is required to clean the silicon wafer after texturing, that is, use acid to neutralize the alkali residue and metal impurities on the surface of the silicon wafer.

5. Edge etching and cleaning

During the diffusion process, a diffusion layer is also formed on the peripheral surface of the silicon wafer. The peripheral diffusion layer forms a short circuit between the upper and lower electrodes of the cell and must be removed. Any small local short circuit on the periphery will reduce the parallel resistance of the High Voltage solar battery and even become a waste product. At present, industrial production uses plasma dry etching, under the condition of photo discharge, fluorine, and oxygen alternately act on silicon to remove the periphery containing the diffusion layer. The purpose of post-diffusion cleaning is to remove the phosphosilicate glass formed during the diffusion process.

6. Deposition of the anti-reflection layer

The purpose of depositing an anti-reflection layer is to reduce surface reflection and increase the refractive index. PECVD is widely used to deposit SiN because when PECVD deposits SiN, it not only grows SiN as an anti-reflection film. At the same time, a large amount of atomic hydrogen is generated. These hydrogen atoms can have dual functions of surface passivation and bulk passivation on polycrystalline silicon wafers and can be used for mass production.

7. Screen printing of upper and lower electrodes

The preparation of electrodes is a crucial step in the preparation process of High Voltage solar batteries. It not only determines the structure of the emission region but also determines the series resistance of the battery and the area covered by the metal on the battery surface. Vacuum evaporation or chemical plating technology was first used, but now screen printing is commonly used, that is, silver pastes aluminum paste (silver aluminum paste) is printed on the front and back of 48v 100Ah lifepo4 battery through a special printing machine and stenciled to form a positive solar battery. Negative electrode lead.

8. Co-firing to form metal contact

The crystalline silicon solar storage battery needs to print the metal paste three times. In the traditional process, it needs two times of sintering to form a good ohmic contact with metal electrodes. The co-firing process only needs one sintering to form the ohmic contact of the upper and lower electrodes at the same time. In the production of High Voltage solar battery screen printing electrodes, chain sintering furnaces are usually used for rapid sintering.

9. Cell test

The completed cells are classified by testing and sorting.

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