## 1 Introduction
On the other hand, in studies published between 2016 and 2020, where battery costs were between EUR 138-400/kWh, it is stated that the use of a PV + ESS system in commercial buildings in Belgium and Germany may be attractive [32; 33; 34; 35; 36]. A detailed financial feasibility analysis is of critical importance in long-term PV + ESS generation facility investments, as in all investment decisions. The most common and reliable method for making an investment decision is cost-benefit analysis [37]. Various metrics such as the levelized cost of energy (LCOE) [38], net present value (NPV) [39], and payback period are used to determine the economic benefits of an investment plan. These metrics can help investors decide whether an investment plan for a PV + ESS plant is worthwhile. The intermittency of PV systems can lead to imbalances in the electricity grid. To mitigate this issue, integrating energy storage systems has become increasingly important [40]. Peak shaving, load shifting, and valley filling strategies enhance the economic feasibility of PV-ESS systems while improving grid stability [41]. Large-scale BESS play a crucial role in balancing the electricity demand curve and increasing energy supply security. Studies have shown that grid losses can be reduced by 10%, and total operating costs can decrease by up to 12% through peak load reduction strategies [42]. In a study conducted in China, integrating demand response (DR) mechanisms with battery energy storage systems was found to increase household self-consumption rates (SCR) to 30.6% and self-sufficiency rates (SSR) to 48.9% [43]. BESS systems also offer significant potential for energy arbitrage and frequency regulation services (FCR). A study in Germany found that optimizing a PV-BESS system for energy arbitrage and FCR services over a 25-year period provided an economically sustainable model by increasing the NPV [44]. Similarly, a 100 MW capacity BESS system was shown to stabilize grid frequency deviations to 0.1 Hz and reduce energy losses by 5% [45]. The implementation of ESS systems has the potential to lower electricity consumption costs for commercial and industrial consumers. [PERSON] et al. (2023), demonstrated that active battery modules could increase the system's lifespan and stored energy capacity by more than 50% [46]. The same study also found that daily energy release increased by 7%, and battery usage time was extended by 51.3%. Other commercial-scale studies have shown that BESS applications, when integrated with demand-side management, significantly lower electricity bills and enhance grid reliability [47]. A study conducted in a residential area in South Africa revealed that a 10 kWh lead-acid battery system could reduce peak loads by 50% [48]. However, the economic viability of BESS largely depends on tariff structures, energy price fluctuations, and investment costs. Research has shown that the economic profitability of BESS is influenced not only by energy storage capacity but also by demand-side management strategies and local tariff policies [49]. In the United Kingdom, as incentives for PV systems declined, the NPV of PV systems dropped from GBP 28,650 in 2011 to GBP 1200 in 2017, but this value could be increased by 46% through ESS integration [50]. Furthermore, economic modeling indicates that BESS implementation can reduce energy costs in the long term, optimizing the investment payback period (PBP) between 5 and 8 years [42; 45].