Turning Retail Stores into Energy Assets - A MILP-Based Optimisation of Integrated Flexibility in a Swedish Local Energy Community

Abstract

The decarbonisation of commercial buildings presents one of Europe’s most pressing energy transition challenges. Retail stores, operating continuously and consuming energy intensively, occupy a unique position at the intersection of building flexibility, on-site renewable generation, and transport electrification. Realising this potential demands coordinated operational strategies that jointly optimise distributed assets against volatile electricity markets, capacity-based grid tariffs, and the emerging opportunity of energy sharing in local energy communities (LECs). This thesis develops and applies a Mixed-Integer Linear Programming model to evaluate the techno-economic and environmental performance of integrated flexibility solutions at a two-building retail LEC case study site in Sweden. The model optimises the cost-optimal dispatch of solar photovoltaic (PV) generation, battery energy storage systems (BESS), ground-source heat pump (GSHP) thermal supply, and electric vehicle (EV) charging covering direct, smart, and vehicle-to-grid modes, over a three-year simulation period across 34 scenarios of progressive technology integration, evaluated against energy, financial, and environmental key performance indicators. Results identify a cost-efficient PV and BESS configuration at the 500 kWp solar production tax threshold that simultaneously maximises self-consumption. GSHP integration proves to be the most impactful single addition, reducing total energy cost by 14%, avoiding 66.7% of baseline CO2 emissions, and yielding an net present value of 3.2 MSEK with a payback period of approximately 9.6 years. The full two-building LEC configuration (S-24) extends this through community-level energy sharing, reaching annual savings of 1.25 MSEK. EV charging adds net electricity cost under all modes, though smart and vehicle-to-grid modes limit this significantly compared to uncontrolled direct charging, which reduces annual savings by up to 23%. Sensitivity analysis identifies spot price level and volatility as the dominant drivers of economic performance, followed by GSHP coefficient of performance. This work addresses a clear gap in the existing literature by providing the first techno-economic optimisation of a retail LEC under Swedish market conditions with simultaneous integration of PV, BESS, GSHP, and three modes of EV flexibility. A two-horizon investment strategy is proposed: immediate deployment of PV, BESS, and GSHP at single-store scale, with full LEC formalisation deferred pending regulatory clarification of energy-sharing arrangements.