The main purpose of a Structural Health Monitoring (SHM) system is to detect changes in the structural condition of Offshore Turbine Platforms that represent deviations from the normal operational behaviour and therefore, indicate the existence of developing faults. This work sheds light on the Structural Health Monitoring system installed for the inspection and maintenance of FRP-based towers of the W2 Power Wind Turbine. The diagnosis of the towers is based on a series of key performance indicators (KPIs), which provide real-time information about the damage state and structural condition of the structural components of the tower. Special attention is also paid to the optimum number and location of the sensors to be installed in the tower. This research is conducted in the framework of the FIBREGY project (Grant number 952966). The FIBREGY consortium is composed of 11 partners specialized in the offshore renewable energy sector and funded partially by the Horizon 2020 program of the European Commission with an overall budget of 8 million.