In order to reduce the greenhouse effect and meet the high demand of electricity, many developed and emerging countries have opted for the use of renewable energies, for example, wind energy, biomass and solar photovoltaic. To determine the economic viability of renewable energy projects it is necessary to capture the most relevant variables that suggest greater interest. Real options allows to consider the dynamic and uncertainties present in the power markets, therefore it is an attractive tool for decision-making in this kind of markets. In this work we apply the traditional technique of project evaluation, the discounted cash flow (DCF), as well as the real real options theory (ROT) for the financial evaluation of a wind farm. The flexibility is the option of making a retrofit investment that allows upgrading the wind turbines technology in order to extend the operating contract. The real option analyzed is analogous to a european call option and its value was calculated through a recombinant binomial tree with barrier in the wind energy price, considered the main source of uncertainty in the model. Sensitivity analyzes were performed to assess the option price behavior when some parameters of the model change. We finally conclude for the economic viability of extending the operation of the wind farm through an investment in retrofit, using the ROT, since its value is much higher than the calculated by the DCF, even though the option value is strongly dependent on the barrier and the volatility of electricity prices.