This paper presents planning models for hybrid distributed generation systems, as well as the results corresponding to a distribution system planning problem obtained using a new computational tool based on a Geographic Information System, GIS. This computational tool is a powerful instrument for analyzing energy resources and energy conversion technologies that can be used for the distribution networks expansion. It has been used in the economic evaluation of energy produced by hybrid systems. Thus, suitable models and techniques have initially been applied to obtain maps of solar and wind energy resources in a user defined area and maps of costs for hybrid systems, identifying the geographical locations that offer the best economic potential in distributed generation with renewable hybrid systems, supported (or not) with fuel to supply internal-combustion electric generators. Accurate evaluations of the cost of the produced energy need the use of geographic distributed costs corresponding to refuelling, installation and maintenance of the hybrid system. The developed software tool is flexible, appropriate for studying different scenarios, and enables geographical analysis of the economic competitiveness of the hybrid systems with different distributed generation resources (photovoltaic, wind, hydraulic or biomass energy systems), and it is suitable to study the optimal expansion of existing power distribution networks (isolated hybrid systems versus connected ones).