*8.1. Economic Analysis*

The economic aspect of building a BESS system is perhaps the most challenging. Preliminary studies created a BESS sizing and siting system to reduce investment costs or optimize profits received once it was implemented. Its cost is determined by numerous aspects, including the type of BESS technology selected, the number of energy source integrations, geographical conditions, features of the deployed region, installation expenses, and maintenance expenses. Technology types differ depending on energy density, efficiency, battery longevity, and cost. Installation and maintenance expenses include the capital for converter interface power, such as energy costs for storage capacity investment, replacement, annual operating and maintenance expenditures. Furthermore, various factors influence the cost of the BESS system, including service life, battery capacity, degradation rate, power loss, and SOC. As a result, its capacity and placement must be properly specified to minimize the installation cost. A BESS capacity that is extremely large is bound to raise the total cost of the system, thereby resulting in power loss. Assuming it is extremely tiny, it reduces efficiency and creates an imbalance in supply and demand.

The uncertainty of the RES system influences BESS cost optimization, such as peak shaving and load shifting. Peak shaving is an efficient method of lowering demand costs by leveling the highest electricity consumption. Meanwhile, load shifting is a temporary reduction in power used followed by subsequent production increases when prices are low. As a result, advanced optimization of the BESS model is required in conjunction with the uncertainty of RES to achieve optimal system planning and operational costs.

#### *8.2. Technology Battery Storage Selection*

Some of the battery technologies for BESS include LA, Li-Ion, Nickel Batteries, ZnBr, NaS, PSB and VRB. The appropriate one can be employed to optimize the system planning or operational costs. Energy density, extended discharge time, battery efficiency, longevity, and life cycle are all factors that determine technology selection. This battery is great for power quality and frequency management applications. It is due to the high-power density possessed as well as the lightning-fast response time. Although this type of battery, with its high energy density and longer discharge time, is ideally suited for long-term applications, it can also be used in certain circumstances to enable peak shaving and load shifting. This is because of the battery's extended discharge period. Therefore, the selection of battery technology is critical to supporting its applications and indirectly impacts the cost of installing BESS.

#### *8.3. Optimal Charge or Discharge*

Selecting the optimal BESS charge or discharge strategy is an important aspect of optimal sizing and tends to influence the life cycle of the battery. When determining the ideal size of a BESS, the most important parameters to take into consideration are speed of charging, rate of discharging, efficiency, and length of service life. Additionally, the effective control of the BESS charge and discharge can contribute to developing more advanced models.
