Achieving Europe’s decarbonization objectives requires a deep electrification of end-use sectors. This transition imposes unprecedented stress on distribution networks, which must accommodate higher peak loads, bidirectional power flows from distributed generation, and increased variability from weather-dependent sources. Addressing these challenges demands not only physical reinforcement but also economic instruments capable of steering consumer behavior toward grid-compatible operation. This thesis develops a comparative optimization framework to assess how different tariff schemes influence both user-side investment decisions and network development. The model integrates a detailed Distribution Network Expansion Planning (DNEP) formulation with Prosumer Energy System (PES) models. Two coordination regimes are compared: a centralized benchmark, where a social planner co-optimizes all assets to minimize total system cost, and a decentralized configuration, where prosumers act independently to minimize their own bills while the Distribution System Operator (DSO) reinforces the grid to ensure its safe operation.