Techno-economic performance simulations play a crucial role in assessing the feasibility, cost-effectiveness, and overall impact emerging renewable energy system designs. Concentrating Solar Power (CSP) is a promising technology for decarbonizing the electricity grid by integrating cost-effective thermal energy storage (TES). However, their development is hindered by their high levelized cost of electricity compared to other energy sources. Hybrid systems that connect with solar photovoltaic (PV) and battery systems are a viable solution to reduce the cost of these plants while maintaining flexibility and guaranteeing firm production despite the intermittence of solar availability. This paper presents MoSES (Modeling of Solar Energy Systems), an open-source techno-economic modeling tool designed to evaluate the feasibility and cost-effectiveness of hybrid PV-CSP plants. While existing simulation tools perform well with established systems, they face challenges when adapting to new components, configurations, and operating strategies. MoSES addresses this challenge by providing a simulation framework and a versatile library of components and control strategies that can be modified to meet end-users’ needs. The tool enables simulation activities to assess the advantages, optimize the design, and benchmark different hybrid PV-CSP plant layouts. This paper outlines the methodology employed to determine system design, costs, and key performance indicators, as well as to estimate operational performance. Furthermore, a case study is presented to illustrate MoSES's effectiveness as a tool for conducting annual simulations despite being in its early stages of development. MoSES provides a valuable contribution to the solar community by enabling the evaluation of the impact of emerging solar-based system designs.