The Finite Element Method (FEM) has been used in the broad field of continuum mechanics in engineering disciplines for several decades. However, recently, some scholars have attempted to apply the method to social science phenomena. What is the scope of using FEM in social science-related fields? Anchored in the literature on social sciences, this paper, firstly, reviews the scope of using FEM in social science phenomena, and then applies FEM to a semi-hypothetical case study on the diffusion of solar photovoltaic systems in southern Germany. By doing so, the paper aims to shed light on why and how the Finite Element Method can be used to forecast the diffusion of solar photovoltaic systems in time and space. Unlike conventional models used in diffusion literature, the computational model considers spatial heterogeneity. The model is based on a partial differential equation that describes the diffusion ratio of photovoltaic systems in a given region over time. The results of the application show that the FEM constitutes a powerful tool by which to study the diffusion of an innovation as a simultaneous space-time process. (C) 2015 Elsevier Ltd. All rights reserved.