Vacuum Technology in PV Industry

  A photovoltaic power generation system refers to a facility that converts solar energy into direct current electricity by utilizing the photovoltaic effect of photovoltaic semiconductor materials. The basic principle is to use the Photovoltaic Effect of semiconductors to form a potential difference on the PN junction inside the solar cell, thereby converting solar energy into electrical energy. Therefore, the solar cell (photovoltaic cell) is the core device that determines the efficiency of photovoltaic power generation. The semiconductor materials used for power generation mainly include monocrystalline silicon, polycrystalline silicon, amorphous silicon, and cadmium telluride.

  The European market is one of the main markets for the global photovoltaic industry. In 2021, European photovoltaic installed capacity will be close to 30GW, accounting for about 18% of the world's. Distributed installed capacity in Europe accounts for about 80%. The main reason is that the overall urbanization degree is high, and the plain area suitable for ground power stations is relatively small. Roof-distributed photovoltaics have more suitable application scenarios. European PV started very early, and before 2012, it was the focus of global PV development on the demand side and manufacturing side.

  The solar photovoltaic industry has a long chain, and many of these processes need to be applied to vacuum technology. Various processes such as crystalline silicon, CdTe, CIGS, or silicon thin film technology in the production of photovoltaic modules are inseparable from the development of vacuum technology.

  Silicon wafer production: When the raw material of polycrystalline silicon is put into the furnace, the crystal growth furnace must be closed and evacuated, and filled with high-purity argon gas, then the graphite heater is turned on, heated to above the temperature (1420 ° C). The raw material melts and begins the subsequent growth process, so crystalline silicon cannot be made without a vacuum.

  Lamination process: The solar cell needs to be encapsulated while connecting the front protection sheet and the rear protection sheet in a vacuum environment.

  Sintering: In the sintering furnace of single-crystal silicon and polycrystalline silicon, the use of a vacuum environment can prevent contamination of impurities and reactions with other gases, and improve the purity of crystal pulling.

  Vacuum is indispensable in the tubular PECVD and ALD processes of PERC (Passivated Emitter and Rear Cell), as well as the plate PECVD and PVD processes of HJT crystalline silicon heterojunction solar cells.

 PECVD (Plasma Enhanced Chemical Vapor Deposition) is a plasma-enhanced chemical vapor deposition method, which uses microwave or radio frequency to ionize the gas containing the atoms of the thin film, and locally forms a plasma in a vacuum environment, and the plasma chemical activity is very strong, very ready to deposit the desired thin film on the substrate.