Lithium Ion Powerwall

Typically, crystalline silicon solar cells are fabricated on high-quality silicon wafers 350-450μm thick, sawn from pulled or cast silicon ingots.

The above methods actually consume more silicon material. To conserve material, chemical vapor deposition (CVD) is currently the most common method used to produce polycrystalline silicon thin-film cells, including low-pressure chemical vapor deposition (LPCVD) and plasma-enhanced chemical vapor deposition (PECVD). Liquid-phase epitaxy (LPPE) and sputtering deposition can also be used to produce polycrystalline silicon thin-film cells.

CVD primarily uses SiH2Cl2, SiHCl3, SiCl4, or SiH4 as the reactant gas. Under a protective atmosphere, silicon atoms react to form silicon atoms, which are then deposited on a heated substrate. Substrate materials typically include Si, SiO2, and Si3N4. However, research has shown that forming large grains on non-silicon substrates is difficult, and gaps between the grains are easily formed.

The solution to this problem is to first deposit a thin layer of amorphous silicon on a substrate using LPCVD, then anneal this layer to produce larger grains. Thick polycrystalline silicon thin films are then deposited on this seed crystal. Therefore, recrystallization technology is undoubtedly a crucial step. Currently, the main technologies used are solid-phase crystallization and mid-zone melting recrystallization. In addition to the recrystallization process, polycrystalline silicon thin-film cells also utilize almost all the techniques used to manufacture single-crystalline silicon solar cells. This significantly improves the conversion efficiency of the resulting solar cells.