Abstract: The present invention provides a method for producing a solar cell comprising the step of immersing a silicon substrate in an etching solution which includes an aqueous sodium carbonate (Na2CO3) solution, optionally an aqueous sodium hydroxide (NaOH) solution and/or an aqueous sodium bicarbonate (NaHCO3) solution to form minute concave and convex patterns on the surface of the silicon substrate. This method allows quite uniform textures to be formed on the crystal faces while avoiding the problem of disposal of isopropyl.

Abstract: In preparing a solar cell, minute projections and recesses are uniformly formed in a surface of a single crystal silicon substrate or a polycrystal silicon substrate by dipping in an etching liquid composed of a mixed acid which is composed mainly of a hydrofluoride acid, a nitric acid and a phosphoric acid in addition to a surface active agent. A solar cell having a substrate in which spherical projections and recesses are formed in a surface of it to which light is incident; an apparatus for producing efficiently a solar cell by realizing the above-mentioned process, and a wet etching apparatus to effect stably the above-mentioned process to thereby maintaining a concentration of a nitric acid to be constant, are provided.

Abstract: A solar cell has a high ability to prevent recombination of electrons near the cell surface, wherein a surface of a p-type substrate at a surface is provided with an n-type region subjected to a treatment with a phosphorus containing acid and a silicon nitride layer is then directly formed on the n-type region.The solar cell can be prepared at a low temperature by a method comprising 1) a step of subjecting the n-type region to a phosphorus containing acid treatment at a low temperature and 2) a step of forming a silicon nitride by a vacuum and thermal CVD method.

Abstract: A solar battery cell, solar battery module, and solar battery module group achieving high product value by enabling the display of surface patterns without reducing the power generating efficiency of the solar battery cells are provided. The direction and/or reflectance of reflected light incident to the surface of the solar battery cell are varied by controlling the distribution of the rough surface structure imparted to the solar battery cell surface. The direction or reflectance of reflected light incident to the surface of the solar battery cell is changed in part depending upon the part of the semiconductor solar battery cell surface to which the light is incident. Semiconductor solar battery cells with high product value can therefore be achieved because patterns with strong visual impact can be displayed and easily recognized without reducing the power generation efficiency of the solar battery cell.