ABSTRACT Over the last few years, the number of solar power plants has increased, the latest being a solar thermodynamic power plant commissioned in February 2016 near Ouarzazate (Southern region) in Morocco. These solar technologies suffer from different types of losses such as optical ones due to the deposit of dust on the mirrors. A degradation process of the solar mirror reduces the reflectance by absorbing and diffusing sunlight, thereby reducing its efficiency, which in turn affects power plant production and the Levelized Cost Of Electricity (LCOE). This work aims to experimentally study the cleanliness of a square mirror in the climatic conditions of eastern Morocco, as well as to exploit the experimental results in simulations that can allow us to have an idea of the energy losses of large plants and their economic impacts. The economic analysis includes the LCOE and the Net Present Value (NPV), while the technical comparison is based on power generation and capacity factors. The results showed that the soiling rate can decrease the monthly electrical production with an average rate of 14,08% and 15,615% for the two technologies Solar Tower (ST) and Linear Fresnel Reflector (LFR), respectively. However, the LCOE increases with an average rate of 16,03% and 18,05%. And thus, ST technology has better technical and economic performance compared to LFR technology.