It is described a blade for a wind turbine for converting wind energy into electric energy, including: a blade structure longitudinally extending along a blade axis (X1) and including a blade tip, an opposite blade root, a longitudinal leading edge portion and a longitudinal trailing edge portion which are extended between the blade root and the blade tip; and an outer aerodynamic shell defining an airfoil including an airfoil leading edge, an airfoil trailing edge and an airfoil suction side and an airfoil pressure side between the airfoil leading and trailing edges. The outer aerodynamic shell includes a suction side panel and a pressure side panel which are made from a transparent material and are fastened to the blade structure so as to define the airfoil suction side and the airfoil pressure side, respectively, wherein the blade includes a transparent region between the transparent panels and wherein the transparent panels are arranged facing one another so that it is possible to see through the blade looking through the transparent panels and the transparent region. A method for assembling the blade is also described.