Within a repowering context, this paper opens a new field of application for visibility and Visual Impact Assessment (VIA) procedures in the decision-making process typical of the design stage of Wind Farms (WF). The proposed methodology presents a test capable of reporting on the visual sustainability of different layouts. It is called Equivalent Visual Impact (EVI). To work with EVI, visibility data have to be numerically available at a level of each pixel and each Wind Turbine (WT). This is called High Resolution Data (HRD). The paper shows how these ideas, EVI and HRD, were applied to a real repowering experience; the result was that the WF could sustain an increment in its power by 37.25% with no additional visual effects. Other associated consequences are discussed.