Evaluating the Impact of Battery Storage Capacity on Energy Flexibility in Buildings

Due to the exhaustion and environmental pollution caused by fossil resources, the share of renewable resources in the energy portfolio continuously increases. Two of the main renewable resources, including photovoltaic and wind, are highly dependent on weather conditions, which leads to increased uncertainty in generation. As a result, the need for different types of flexibility, especially energy flexibility, in energy systems is increasing. One of the important sources of energy flexibility is energy storage systems. In this paper, the effect of different capacities of battery energy storage systems (BESSs) and different photovoltaic capacities on the energy flexibility of a smart building is investigated. To achieve this, changes in the self-consumption index (SC) for different capacities of photovoltaic systems and BESS are analyzed. PV capacities of 165,330, and 495 kW are chosen. which generated <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$28.5 \%, 57 \%$</tex>, and 85 % of the building's cumulative energy consumption during one year, respectively. The results show that as the difference between generation and consumption increases, the addition of the same BESS capacity leads to a greater increase in the SC. Adding BESS with 100 % and 200 % PV capacity at 495 kW PV capacity resulted in SC improvement of 15 % and 7 %, respectively. Adding the same percentage of BESS at 330 kW PV capacity resulted in about 9 % and 2 % improvement in SC. While in the PV capacity of 165 kW, the amount of changes of SC was around 2 % and less than 1 %.