This paper is to select the best locations to build solar photovoltaic farms (large grid-connected photovoltaic systems which have more than 100 kWp of installed capacity), with the coast of Murcia in the southeast of Spain being used as an example. In order to solve the problem, the suitable locations to implant such facilities will be identified by a Geographical Information System (GIS). To obtain the weights of the criteria which influence the proposed problem, the Analytic Hierarchy Process (AHP) will be employed. Then, the suitable locations will be evaluated and classified using two different multi-criteria decision methods, the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) and ELimination and Choice Expressing Reality (ELECTRE), in this case the version TRI. We are thus also able to establish a comparison between the two methods. This comparison demonstrates how although the results do not completely coincide, some similarity can be seen between the two methods.