NOVELTY - The method comprises melting a glass composition to form a glass melt, pouring the glass melt in a flat glass chamber for forming flat glass on a bath of molten tin or a molten tin alloy (9) or rolling molten glass (5) between forming rollers for forming flat glass, and conveying the flat glass from the flat glass chamber or from the rollers into an annealing chamber for annealing the flat glass. Before or during or directly after the annealing, the flat glass is etched on a surface, which is in contact with the molten tin or molten tin alloy. A nanostructured surface is formed on flat glass.    USE - The method is useful for producing flat glass, which is useful for producing a glass pane of a solar module (all claimed) or a solar cell, where the flat glass is produced in the form of ribbon.    ADVANTAGE - The method is capable of simply producing the flat glass with improved anti-reflecting and mechanical properties and reduced thickness thus enhancing self cleaning characteristics of the glass pane and lifespan and efficiency of the solar module.    DETAILED DESCRIPTION - The method comprises melting a glass composition to form a glass melt, pouring the glass melt in a flat glass chamber for forming flat glass on a bath of molten tin or a molten tin alloy (9) or rolling molten glass (5) between forming rollers for forming flat glass, and conveying the flat glass from the flat glass chamber or from the rollers into an annealing chamber for annealing the flat glass. Before or during or directly after the annealing, the flat glass is etched on a surface, which is in contact with the molten tin or molten tin alloy. A nanostructured surface is formed on the flat glass, which is etched by reactive ion etching and wet etching. The reactive ion etching is carried out by using a sulfur hexafluoride plasma, carbon tetrafluoride plasma, fluorine plasma and/or chlorine plasma or hydrogen fluoride. The etching is carried out at a temperature of 200-800 degrees C. The surface of the flat glass is toughened or tempered by a chemical process or by heating just below its softening temperature of the flat glass and by cooling the flat glass immediately after the heating, where the toughening or tempering is carried out after the etching of the flat glass. INDEPENDENT CLAIMS are included for:    (1) a glass pane; and    (2) a solar module.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a flat glass production with a plasma reactor for carrying out a reactive ion etching.    Glass furnace (4)    Molten glass (5)    Tin bath chamber (8)    Molten tin alloy (9)    Etching unit. (20)