Electricity is of vital importance to human beings, and studies on the maintenance, increase, and improvements of the electrical energy used are of great importance to today’s society. Thus, the objective of this work focuses on the analysis of the application and validation of a forecasting model using the complex exponential smoothing (CES) method, based on daily data from a medium-sized photovoltaic power generation system installed in the city of Sinop-MT, and programmed to generate 500 kWh daily, during the period from 06/05/2022 to 28/04/2023, and generating forecasts from 01/03/2023 to 28/04/2023. The models with and without outliers were adjusted, and they provided similar results, but the model that presented the best results was the one without outliers, which generated an average forecast of 433.63 kWh, and an average over the entire series of 481.35 kWh, and with RMSE = 84.95, and through the forecast analysis of this model, it was observed that it was able to reveal good results related to the generation of photovoltaic electricity generated by the system installed in Sinop-MT, in the periods ahead.