NOVELTY - The method comprises contacting at least one surface of a silicon (Si) wafer as cut with an acidic etching agent, where the wafer is, prior to the acidic etching, not subjected to an alkaline etching step or process. The Si wafer is a monocrystalline or a quasi-monocrystalline Si wafer, and is saw-damaged and/or cleaned prior to etching. The acid etching agent is an aqueous solution. The acidic etching agent is contacted with the surface of the Si wafer for once or several times. The contacting step comprises dipping, spraying, coating or printing.    USE - The method is useful for acidic etching of a silicon wafer, which is useful in a solar cell such as passivated emitter rear cell (PERC) solar cell of a solar module (all claimed).    ADVANTAGE - The method: allows rapid and economical acidic etching of the silicon wafer due to less cleaning steps and usage of low grade chemicals; and is capable of acidic etching the silicon wafer with controlled surface roughness and without metallic and organic contaminants, thus providing the wafer with thin size and improved yield, increasing lifetime of the solar cell and preventing degradation of the solar cell.    DETAILED DESCRIPTION - The method comprises contacting at least one surface of a silicon (Si) wafer as cut with an acidic etching agent, where the wafer is, prior to the acidic etching, not subjected to an alkaline etching step or process. The Si wafer is a monocrystalline or a quasi-monocrystalline Si wafer, and is saw-damaged and/or cleaned prior to etching. The acid etching agent is an aqueous solution. The acidic etching agent is contacted with the surface of the Si wafer for once or several times. The contacting step comprises dipping, spraying, coating or printing. The method further comprises: generating a silicon dioxide/silicon nitride (SiNx) passivation layer or an aluminum oxide/SiNx passivation layer on one surface of the Si wafer after the acidic etching process; performing an alkaline texture etching process conducted after the acidic etching of the Si wafer surface and optionally after the generating step or after laser ablation process to texture etch a front surface and an ablated pattern at wafer rear-side; and doping the Si wafer with phosphorus in order to modulate the electrical properties of the wafer. The method is a part of an in-line process.    DESCRIPTION OF DRAWING(S) - The diagram shows a flowchart of a method for acidic etching of a silicon wafer. (Drawing includes non-English language text).