A wind farm does not operate at nominal power output all the time around the year due to the intermittent nature of the wind and thus leaving a chance to further utilize the transformer rating by adding another power generation. Since the necessary infrastructure for grid connection has been already laid out for the wind farm, adding a certain capacity of photovoltaic power to the low voltage side of the transformer offers a potential to optimize the power production of the hybrid plant at a reduced initial investment. In this thesis, the study aims to optimize the power production of a grid connected wind farm by adding photovoltaic panels. The studied wind farm, located in Gotland Island in southern Sweden, contains three wind turbines with a nominal capacity of 150 kW each; totaling to 450 kW of wind power and coupled to the grid by a utility owned transformer of 500 kVA capacity. Total power production resulting from the addition of a certain photovoltaic power is analyzed on hourly basis in order to keep it below transformer’s rating. A total power production exceeding 500 kW will result in an overload and is reduced to 500 kW thus resulting in losses. Hourly wind power production data was provided by the operator for a period of one year, and solar irradiance data for the same year was obtained from SMHI “Swedish Meteorological and Hydrological Institute” for Gotland isle. The power production from a specified photovoltaic module was simulated for different photovoltaic capacities at different tilt angles and the estimated total generated power was analyzed with an aim to add as much photovoltaic power while keeping overloads to a minimum. In this studied case, the utility company owning the transformer requested that the maximum allowed power should be 450 kW (50 kW below the nominal rating) although previously the wind farm was allowed to deliver up to 550 kW active power. It is shown that the amount of photovoltaic power that can be added, while keeping lost power due to overloads at a minimum of 1% of total generated power, is highly dependent on transformer rating. The transformer rating of 450 kW 500 kW and 550 kW resulted in potential photovoltaic peak power of 125 kWp 325 kWp and 425 kWp respectively to be added. Optimizing the added photovoltaic power in a way to minimize total power standard deviation on yearly basis (series of twelve months) results in a recommended peak capacity of 500 kWp or 110% of the rated wind power, while a suitable transformer will be rated at 700 kVA.