Among the various stages of development of a conceptual project for a photovoltaic power plant, the elaboration of the Annual Energy Production Certification (CPAE) is essential. This certification allows the entrepreneur to attest to the energy generation potential of the project. The Annual Energy Production Certification is required by the electric sector bodies that authorize the implementation and operation of new electric power generating plants, being a necessary requirement to prove the project's generation potential. This work presents a revisitation of the analyzes to estimate energy production, with details on each type of loss experienced by the system, and, finally, a case study is presented with the description of the parameters that influence the energy estimation. The simulations use the PVSyst program, a tool usually used in the certification processes of photovoltaic plants connected to the Brazilian electrical system. The estimated energy production, the main result of the simulations, has a relative error of +0.33% compared to the certified value for the enterprise.