Efforts to incorporate renewable energy sources into current and future electricity regimes have been brought about due to the challenge of an increasing demand for electricity worldwide, retirement of aging conventional generation facilities, along with the consequences of greenhouse gas emissions from existing conventional energy sources. This paper presents a decision support tool to locate potential sites for large-scale solar power projects focusing on transmission line issues on a state level. Geographic Information Systems (GIS) and Multi-Criteria Decision Analysis (MCA) were combined to complete a site suitability analysis. GIS and MCA were incorporated to develop a hierarchical process for assigning site suitability to land resources, mapped with respect to technical, environmental and economic parameters. A series of maps was created with GIS software to illustrate possible locations for large-scale solar power projects on two levels with respect to transmission issues. Resulting locations were analyzed according to populated areas and existing transmission lines. Wyoming was chosen as a case study based on its location as an outlying region to the south-west, large open land areas, and significant annual solar resource (between 4.5 and 6 kWh/m2/day total average annual irradiation) using solar resource maps from the National Renewable Energy Laboratory (NREL). Wyoming was also chosen because of the state's long history of high energy production (i.e. coal from the Powder River Basin) and unusually high energy demand per capita (no. 1 in the nation).