In 2020, the average thickness of polycrystalline silicon wafers is 180 μm, the average thickness of P-type monocrystalline silicon wafers is about 175 μm, the average thickness of N-type silicon wafers is 168 μm, the average thickness of N-type silicon wafers for TOPCon cells is 175 μm, and the average thickness of silicon wafers for heterojunction cells About 150 μm.
1. P-type monocrystalline silicon wafers: Thin slices have experienced multiple nodes such as 350 μm, 250 μm, 220 μm, 200 μm, and 180 μm, and are expected to reach 170 μm in 2021. The thin slice technology of 150-160 μm has matured and is expected to reach 160 μm in 2025 .
2. N-type monocrystalline silicon wafers: Compared with P-type silicon wafers, N-type silicon wafers are easier to achieve thinning. It is expected to reach 160-165 μm in 2021. Currently, 120-140 μm wafer technology is available, and it is expected to reach 100-120 μm in the long run.
3. N-type monocrystalline silicon wafers for heterojunction cells: HJT is the most favorable cell structure and process for thinning, and has natural advantages in thinning. The reasons are:
(1) Symmetrical structure, low temperature or stress-free process can be adapted to thinner silicon wafers.
(2) The conversion efficiency is not affected by the thickness. Even if the thickness is reduced to about 100 μm, depending on the ultra-low surface recombination, the loss of the short-circuit current Isc can be compensated by the open-circuit voltage Voc.
According to relevant predictions, the thickness of heterojunction N-type silicon wafers will reach 140, 130, and 120 μm in 2024, 2027, and 2030, respectively, and the theoretical limit of thinning can reach below 100 μm.