Consumption of non-renewable resources such as oil, gas and coal is increasing every day. But when these resources run out, we have to look for renewable energy such as solar, wind and geothermal. Solar energy is a clean energy that can reduce the production of environmental pollution and is the beginning of reducing carbon from human life. One of the most important issues in the construction of solar power plants is to determine the places that have a high potential for solar energy. This research has been done in order to locate solar power plants using multi-mechanical decision-making methods of participation in Fars province. In the initial studies on the region and the current state of solar power plants, and then using the resources and opinions of experts, 10 effective criteria, including climatic, geomorphological and economic criteria in the location of solar power plants have been selected. Criteria information layers are prepared in GIS environment and then the best-worst and Denp methods are used to weigh the selected criteria. In the first method, two criteria of sunshine hours and distance from roads and in the second method, the criteria of sunshine hours and distance from the fault have been performed as the most important and the least best criteria, respectively. Due to the different methods of these two techniques, the results of its losses have been used for the final weight of the criteria. After weighing the criteria, zoning has been done and 8 places have been proposed for the construction of a solar power plant in Fars province. In the last step, using Coopras and TOPSIS methods, the places whose proposals are ranked and for the final results, the integration of these two methods with the ranking technique is used. The methods used in this research are programmed in Linux and MATLAB software environments. Finally, the No. 8 reality site in Zarrin Dasht city of Fars province has been selected as the best location for the construction of a solar power plant.