NOVELTY - The method comprises: providing a liquid bath (100) comprising silicon, a n-type dopant and a p-type dopant; conducting directional solidification of silicon in a direction, by varying parameters for convection-diffusion growth of alternate layers (101) of n-doped silicon and layers of p-doped silicon (102); and obtaining a cutting edge (104) parallel to the direction of the multilayer structure at the end of directional solidification so as to obtain the wafer. The method further comprises growing an intermediate layer (103) between growth of n-doped and p-doped silicon layers.    USE - The method is useful for manufacturing a wafer in monolithic silicon vertical multi-junction to produce a photovoltaic system (all claimed) such as photovoltaic solar cell.    ADVANTAGE - The method is capable of dividing the silicon wafers into a set of smaller sub-cells, and producing photovoltaic modules having higher open circuit voltage, while maintaining size of the modules.    DETAILED DESCRIPTION - The method comprises: providing a liquid bath (100) comprising silicon, a n-type dopant and a p-type dopant; conducting directional solidification of silicon in a direction, by varying parameters for convection-diffusion growth of alternate layers (101) of n-doped silicon and layers of p-doped silicon (102); and obtaining a cutting edge (104) parallel to the direction of the multilayer structure at the end of directional solidification so as to obtain the wafer. The method further comprises growing an intermediate layer (103) between the growth of n-doped silicon layers and p-doped silicon layers, where the ratio between a density of charge carriers of electron and density of charge carriers of holes of the intermediate layer is 1. The silicon solidification step is effected by a pulling method including Czochralski pulling method or Bridgman drawing method, and is effected by varying the speed of solidification of the silicon according to a specific repetition cycle with suitable speed conducive to the growth of n-doped silicon, speed conducive to the growth of p-doped silicon and speed conducive to the growth of the intermediate layer. The variation of the convection-diffusion parameter is effected via the variation of the solidification rate of the silicon, in particular between the value conducive for growth of the n-doped silicon and the value conducive to the growth of p-doped silicon. A solidification rate of the silicon is adjusted via the control of the drawing speed. The variation of the convection-diffusion parameter is effected via the variation of the level of mixing of liquid bath, where the level of mixing of the liquid bath is adjusted by a mixing system such as by forced rotation of a crystal and/or a crucible, using an alternating magnetic field, and by rotating or sliding a mechanical blade, propeller or disc. Silicon in solid or liquid form is added to the liquid bath during solidification step. The n-doped silicon and p-doped silicon are adjusted in respective durations of the solidification step so that the n-doped layers and the p-doped are formed independently of each other with thickness of 5 mm to 5 cm. INDEPENDENT CLAIMS are included for:    (1) a silicon wafer; and    (2) a photovoltaic system.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic cross sectional view of a multilayer structure.    Liquid bath (100)    N-doped silicon layers (101)    P-doped silicon layers (102)    Intermediate layer (103)    Cutting edge. (104)