Experimental investigation and numerical model validation of a 2.5 kWt concentrated solar thermal plant

•A 2.5 kWt Concentrated Solar Thermal Power system has been designed and tested.•The tests campaign has shown high performance and efficiency of the prototype plant.•A numerical model has been developed to support the CSP plant design.•The simulated and experimental data were in good agreement even with varying DNI.•The validation of the model makes it a potential useful tool for CSP plants design. In this paper the design of a 2.5 kWt Concentrated Solar Thermal Power system is reported. The prototype plant uses 25 heliostats for a total active area of 4.4 m2. Each mirror is moved by a two-axis tracking mechanisms to reflect the sun’s rays onto a fixed target having an area of 0.5332 m2. Tests have been carried out in order to obtain a complete comprehension of the system’s performance under different operating conditions. The prototype plant was installed in a town of central Italy and the experimental analysis allowed to assess the overall plant performance in terms of thermal power and efficiency. In particular, the daily energy production and the plant efficiency reached a peak value of about 22.5 kWh and 71.71% while the mean values were 13.75 kWh and 60.50% respectively. The plant output has also been investigated using an analytical model previously developed to support the prototype design. The analytical model takes into account the main losses related to the heliostat systems. In general, the simulation results were in good agreement with the experimental data. The validation of the proposed numerical model makes it an efficient tool to support the design of other small scale concentrated solar thermal plants.