Heterojunction solar cells have always been favored by solar cell manufacturers and photovoltaic enterprise users for their low production costs and ideal photoelectric conversion rates. However, in order to further improve the photoelectric conversion rate of solar cells, they can be sliced chemical treatment.

Effects of low-temperature process for heterojunction solar cells

    An important feature of heterojunction solar cells is that they use a low-temperature manufacturing process. Generally, solar cells can be manufactured below 200°C, thus avoiding the annealing process and oxidation process of silicon wafers and maintaining the high quality and quality of silicon wafers. Low defects. The low-temperature process also makes it easier for heterojunction solar cells to achieve thinning of silicon wafers, that is, reducing the thickness of silicon wafers, thereby reducing the amount and cost of silicon materials and improving the photoelectric conversion rate and mechanical strength of solar cells.

The important role of thinning heterojunction solar cells

    The thinning of solar cells is an important direction for cost reduction and growth in the photovoltaic industry. Currently, the average thickness of polycrystalline silicon wafers is 180 μm, and the thickness of P-type monocrystalline silicon wafers and N-type monocrystalline silicon wafers for TOPCon cells is 175 μm. The thickness of the silicon wafer of mass junction solar cells can be reduced to 150μm or even lower. According to statistics, every time silicon wafers are thinned by 20 μm, the price can be reduced by 10%, and the corresponding component price can also be reduced by 5-6 cents/Wp. In addition, the thinning of solar cells can also reduce the series resistance of solar cells, increase the filling factor of the solar cell, and improve the photoelectric conversion rate of the solar cell.

    The thinning of heterojunction solar cells will not affect the light absorption of solar cells, because the PN junction of heterojunction cells is formed on the surface of the silicon wafer, not in the body of the silicon wafer, so the thickness of the silicon wafer has an important impact on solar energy. The light absorption of the solar cell does not have much impact. On the contrary, thinning the silicon wafer can reduce the weight of the solar cell and improve the flexibility of the solar cell.

Technical difficulties in thinning heterojunction solar cells

    The thinning of heterojunction solar cells also requires solving some technical problems, including cutting, handling, cleaning, passivation, and coating of silicon wafers. Silicon wafer cutting requires the use of high-precision cutting equipment to avoid damage and waste of silicon wafers, while ensuring the consistency of the size and flatness of the silicon wafers. The transportation of silicon wafers requires the use of high-efficiency automated equipment to avoid damage and contamination of the silicon wafers, while ensuring the accuracy of the positioning and arrangement of the silicon wafers. Silicon wafer cleaning requires the use of high-purity cleaning fluid to remove impurities and cutting residues on the surface of the silicon wafer, while ensuring that the silicon wafer is dry and dust-free. Passivation of silicon wafers requires the use of high-quality passivation layers to improve the surface charge and carrier lifetime of the silicon wafers while ensuring the uniformity and stability of the passivation layer. The coating of silicon wafers requires the use of high-efficiency coating equipment to form high-quality heterojunction and transparent conductive oxide films - ITO films, while ensuring the thickness and structural consistency of the coating layer.