## 1 Introduction  
Since 2014, and for five consecutive years, the net annual addition power from renewable energy resources has exceeded the net addition power from fossil fuel and nuclear power capacity combined, making such resources count for 27.3% of the global electricity generation [1]. Solar photovoltaic (PV) and wind technology are considered the fastest in growth compared to all other renewable resources. Solar PV technology can be installed as large-scale centralized PV plants or distributed, e.g., as rooftop PV systems. On the other hand, the wind is usually in the form of a centralized onshore or offshore wind farm, consisting of groups of wind turbines. In 2019, one-fifth of the global renewable capacity was in the form of small to medium size solar PV panels deployed on residential or commercial building rooftops [2]. The rooftop PV systems can assist not only in deferring the need for distribution network reinforcement but also in providing various ancillary services [3].  
However, the integration of the rooftop PV systems brings about various operational issues due to the stochastic behavior of the energy coming from the sun. For instance, the frequency deviates due to the variation in the load in the grid and is even more compromised as the fluctuation in PV power output increases. However, the voltage quality problem is considered the most severe obstacle to distribution system operators (DSO), which is the focus of this study. According to [4; 5], the voltage problem represents the most significant issue that must be controlled for an efficient operation of grid-connected solar PV. Unlike traditional passive distribution systems where the load level is the only unpredictable element, PV systems integration poses additional uncertainty levels for the DSOs and utilities. In distribution systems, on-load tap-changing transformers and capacitor banks at the substation are typically employed to keep the network voltage magnitude within acceptable bounds [6]. Nevertheless, these devices cannot react as fast as required and may degrade their service life [7; 8].  
Expensive distribution upgrades are typically necessary when addressing voltage challenges. Nevertheless, battery energy storage systems (BESS) are regarded as potential solutions for controlling the voltage in distribution systems. The BESS applications have been increasing in the power system field, particularly after PV system penetration into distribution systems [9]. BESS can provide various services, such as voltage support [9], frequency regulation [10], load shifting [11], peak shaving [12], network expansion deferral [13], and greenhouse gas reduction [14]. Therefore, many countries are embracing the development of BESS and facilitating such deployment in their national programs [15]. In the distribution network, the battery converts electrical energy from the grid or the excess power from the PV system into a form that can be stored. After that, it discharges the energy back to the grid or load when required with almost zero emissions.  
Nevertheless, the primary concern with BESS is the associated high initial cost. Yet, with the continuous developments in the batteries field, the BESS prices have been decreasing noticeably over time. Such developments permit their deployment in distribution systems to regulate the voltage. However, improper usage, misallocating, or the non-optimal operation of the BESS in distribution networks may affect the reliability and degrade the voltage quality. Therefore, the successful implementation of batteries depends mainly on the planning strategy where location, size, and operational characteristics should be considered. Some studies use BESS to improve distribution network load [16; 17], while others discuss the BESS applications for peak load shaving [18; 19].