NOVELTY - The coating has an antireflection inner layer (6) that is made of porous silicon and formed on a flat solar cell panel (2). An outer layer (8) is made of silicon oxynitride, non-porous and free from foreign species e.g. hydrogen, where the layer (8) is on the inner layer which a thickness between 42 and 53 nanometers. The porous silicon is formed on the solar cell panel by an electrochemical anodization process. The anodization conditions are such that the layer (6) has a refractive index comprised between 2.6 and 2.9.    USE - Used for being formed on a solar cell (claimed) e.g. flat solar cell, silicon solar cell, monocrystalline, polycrystalline or microcrystalline solar cell, for limiting reflectance of a radiation such as visible, infrared and ultraviolet radiations, via a surface on which it falls.    ADVANTAGE - The coating has a small coefficient of reflectance in a range of wavelengths from 470 to 650 nanometers, thus obtaining maximum solar radiation and increasing conversion efficiency of the silicon solar cell. The outer layer is made of silicon oxynitride and non-porous, thus permitting the inner layer to be effectively protected against degradation. The silicon oxynitride is free from foreign species, thus allowing to obtain stable and satisfying physical and chemical properties, and hence improving the optical properties of the outer layer. The spectral range of the solar cell provided with the coating is effective and depends on the thickness and the refractive index of the inner and outer layers.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) a solar cell comprising an anti-reflecting coating    (2) a method for forming an anti-reflecting coating on an exposed solid silicon surface.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a solar cell panel with an anti-reflecting coating.    Flat solar cell panel (2)    Anti-reflection coating (4)    Antireflection inner layer (6)    Outer layer (8)