摘要： Phovoltaic generation have been increasing around the world as an important alternative of energy production. Therefore, studies to foresee the impact of inclusion of this type of energy in the network become necessary. For this goal, the representation of these photovoltaic generators by equivalent model and the estimation of its parameter is an important area to study. Usually manufactures of photovoltaic modules provide some information to obtain model parameters of those panels using standard test conditions. However, in real situation, rarely those conditions are similar of those where the photovoltaic modules are installed. In this research a method for parameter estimation of equivalent photovoltaic power plant model is proposed using real measuremets. The improved single diode model was select to represent the photovoltaic system and the mean-variance mapping optimization method was used to estimate the parameters. A comparison between the parameter estimated with standard test condition and with real measurements was performed in a real photovoltaic system installed in Sao Paulo University. The results have shown differences between parameters estimated with real measurement compared with stander test condition, especially a parallel and series resistances.