Due to the future energy transition to renewable energy sources there is great need to develop relatively inexpensive and reliable generators. That is why the wind turbines gain high interest among researchers in the last few decades. Due to their advantages, like omnidirectionality, low noise generation or low susceptibility to turbulence, the vertical axis wind turbines (VAWTs) are of special interests. This paper aims at presenting the full two-way Fluid Structure Interaction (FSI) model of the H-Rotor type VAWT. The developed model couples Unsteady Reynolds Averaged Navier-Stokes Equations (URANS) methodology with the dynamic mesh method and non-linear structural Finite Element Method solver to simulate operation of the H-Rotor turbine having the turbine rotor made of carbon composite. The carried out calculations provide detailed information on the instantaneous flow fields around the operating wind turbine and stresses and deformations of the turbine rotor caused by the air flow. This allowed us to determine instantaneous and average power produced by the wind turbine and influence of the unsteady deformations of the turbine rotor on its performance. Moreover, obtained results allowed us to assess the construction safety. The simulations were carried out using the commercial ANSYS Fluent and ANSYS Mechanical software.