Optimal sizing of PV-BESS units for home energy management system-equipped households considering day-ahead load scheduling for demand response and self-consumption

Abstract

Today, selling electricity to the grid has lost its former profitability with reduced feed-in tariff (FiT) rates. This makes it crucial for prosumers to increase self-consumption and size their photovoltaic (PV) and battery energy storage system (BESS) units accordingly. Self-consumption can be increased through demand-side management (DSM) and an efficient DSM can be achieved using home energy management systems (HEMSs). Therefore, as its main contribution, this study proposes an optimal PV-BESS sizing model for HEMS-equipped prosumers considering day-ahead load scheduling-based DSM. Unlike other studies in the literature, the proposed model takes into account the determination of optimal PV tilt angle, load scheduling of all types of controllable appliances (time-shiftable, thermostatically controllable, power-shiftable), consideration of battery degradation, and vehicle-to-home (V2H) availability in the sizing procedure. First, the mixed-integer linear programming (MILP)-based model performs demand response (DR) and increased self-consumption to minimize the daily bill. Second, it simulates one year of HEMS operation and determines the net present value (NPV) of a PV-BESS configuration over the system lifetime. Finally, it repeats the same process for each combination of PV capacity-PV tilt angle-battery number and chooses the combination with the highest NPV as the optimal design.The simulations were conducted to find the required PV-BESS capacity for a HEMS-equipped household with average daily electricity consumption of 37.5 kWh in Istanbul, Turkey. The optimal configuration was found to be 3 kW PV without BESS at the tilt angle of 10°. A techno-economic sizing comparison was made between households using and not using HEMS. The NPV of PV-BESS was found to be significantly higher with HEMS use ($2273) compared with that without HEMS use ($920). Lastly, a sensitivity analysis was performed based on rising electricity prices (+25%, +50%, +75%, +100%) and declining battery prices (−25%). The use of BESS became viable in Turkey even with +25% electricity prices or −25% battery prices.