As urban environments become more complex and built-up there is reduced space on roofs for photovoltaic systems, meaning there is an opportunity to develop façade (wall) integrated photovoltaic systems. However, to facilitate this, there is a need to be able to quantify the solar radiation received by specific building facades. As such, this work examines a method for computing solar energy potential of facades in an urban environment. The potential is presented in terms of the ratio of direct solar energy accumulated on facades when the shadowing effects of buildings are considered, to that of an ideal scenario when these shadowing effects are ignored. In achieving this, the method utilizes several spatial-scaled geo-information models, including a 2.5D Digital Surface Model, and the temporal-scaled solar irradiation model such that it is able to assess the potential in a given period. A unique shadow algorithm is also designed to be easily converted into a computer program in which the time and computer memory required for the assessment is independent of the complexity of a given relief. To illustrate this work, a case study considering a hypothetical building layout and orientation is presented.