Preparation method of MWT solar cell

Abstract

The invention relates to a preparation method of a cell, in particular to a preparation method of an MWT solar cell, and belongs to the technical field of MWT solar cell module processing. The preparation method of the MWT solar cell comprises the steps: performing punching, texturing and diffusion of a silicon wafer, and then performing etching, oxidation annealing, back passivation, front coating, laser grooving, silk-screen printing and sintering to form ohmic contact; and finally obtaining the MWT solar cell. The etching step comprises the substeps: removing phosphorosilicate glass on theback surface and four side surfaces of the silicon wafer, and then adding reaction solution for alkali polishing to obtain the back surface with the reflectivity of 40-50%. Compared with an acid etching process, the groove type alkali polishing process has the advantages that the back polishing effect of the silicon wafer is more excellent, the weight is reduced, and the fragment risk is reduced;the back reflectivity is higher, the internal reflection effect of a long wave band is improved, uniform deposition of a passivation film Al2O3 is facilitated, the passivation effect on a silicon wafer is improved, and the battery efficiency gain is at least 0.15% compared with the prior art.

Description

technical field [0001] The invention relates to a method for preparing a battery, in particular to a method for preparing a MWT solar cell, and belongs to the technical field of MWT solar cell module processing. Background technique [0002] Metal-wrapped silicon solar cells (MWT) have attracted more and more attention because of their high efficiency, small shading area, better appearance characteristics, and ease of integration with existing traditional crystalline silicon processes. MWT silicon solar cells use laser drilling to transfer the energy collected from the front through the cell to the back of the cell to reduce the shading area and improve conversion efficiency. For example, CN201410016190.6 provides a low-cost preparation method of MWT, adding two processes to the traditional crystalline silicon cell production process, namely: laser drilling before texturing and mask printing after diffusion. In the current high-efficiency cell technology on silicon substrat...

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Problems solved by technology

But PERC cells are plated with Al 2 o 3 The passivation process has very high requirements on the cleanliness of the back of the battery, so the etching and cleaning process is very important, and the mask process in the MWT battery preparation process needs to be cleaned in the etching process. The conventional mask uses paraffin wax. In the actual production process The cleaning effect of alkali and diethylene glycol monobutyl ether is not ideal for the PERC process, resulting in the superposition of MWT and high-efficiency PERC process not achieving the optimal cell efficiency result, which is an urgent problem to be solved

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