Designing a small hydropower plant (SHPP) necessitates fulfillment of energy and ecological constraints, so a well-defined design flow is of the utmost significance. The main parameters of each SHPP are determined by appropriate techno-economic studies, whereas an improved approach to defining more precise SHPP installed parameter is presented in this paper. The SHPP installed parameter is the ratio of the design flow and averaged perennial flow obtained from the flow duration curve at the planned water intake location. Previous experiences in the design of SHPPs have shown that the SHPP installed parameter has a value in a wide range without the existence of an unambiguous equation for its determination. Therefore, with this aim, the thirty-eight (38) small watercources in the territory of Montenegro, denominated for the construction of SHPPs, have been investigated. SHPPs are divided into two groups depending on the installed capacity and the method of calculating the purchase price of electricity. For both groups, the range of SHPP installed parameter is determined according to the technical and economic criteria: the highest electricity production, the highest income, net present value (NPV), internal rate of return (IRR), and payback period (PB).

The study compares performance predictions from blade element momentum theory, CFD methods, and experimental results for a 2.5 MW horizontal wind turbine across various wind speeds. The results indicate that CFD or in complex flow conditions, although blade element momentum theory remains useful during the initial design stages. The analysis also underscores the influence of wind speed and shear stress transport on performance metrics such as turbine power output and flow characteristics. Despite certain modelling simplifications, such as the omission of detailed blade tip geometryies, the findings suggest that both numerical methods exhibit trends consistent with the field experimental data. The study highlights the importance of detailed simulations for optimizing wind turbine performance and outlines future research focused on noise reduction and its impact on biodiversity.