This chapter presents a comprehensive framework for modelling and economic analysis of microgrids, integrating both technical and financial dimensions. Microgrid modelling supports optimal design, scenario planning, and operational strategy through both model-based and data-driven approaches. Key components such as distributed energy resources (DERs), energy storage systems, loads, electric vehicle supply equipment (EVSE), and power converters are discussed in detail, along with their control systems and interaction in various topologies. The chapter outlines steady-state and dynamic power flow modelling, unbalanced network analysis, and state estimation techniques to assess microgrid performance under different operational conditions. Advanced inverter functions and smart control strategies are highlighted to ensure voltage and frequency stability in both grid-connected and islanded modes. Economic evaluation methods, particularly Net Present Value (NPV) analysis, are also introduced to compare investment decisions and lifecycle costs of different microgrid configurations. The chapter emphasises data requirements, including component specifications, time-series profiles, and meteorological inputs, to support accurate simulation and planning. By synthesising technical and economic insights, this chapter guides practitioners in developing resilient, cost-effective, and scalable microgrid solutions tailored to diverse use cases, regulatory environments, and market structures.