## 1 Introduction  
In 2023, the global cumulative installed photovoltaic (PV) capacity was 1642 GW. If compared with 2022 (1186 GW), it shows a growth of 38.4% [1], which is divided between centralized and utility-scale segments into 59% (269.9 GW) and 41% (186 GW), respectively. To keep such a deployment rate and reach the so-called net zero emission scenario, the International Energy Agency forecasted a need for global PV manufacturing capacity growth of about 1260 GW / year until 2030 [2]. Considering the European boundaries, the European Union (EU) agreed on setting a target value of 32% for the energy demand covered by renewable energy sources (RESs) by 2030, starting from 21.8% in 2021. To reach the target, the REPowerEU Solar Energy Strategy Plan forecasted a total PV capacity deployment of 600 GW by 2030 inside the EU borders [3]. In fact, the production of electricity from solar energy has been continuously increasing, especially since 2008, as can be seen in [4], underlining the European commitment to reach the net zero emission scenario by 2050 and the need for a more resilient energy management structure, evaluated in [5, 6]. Parallelly, the research community continues evaluating new solutions to increase the energy harvest potential of PV modules and their reliability, as conducted in [7]. Among many, bifacial PV modules (bi-PVs) are gaining relevance. This is because bi-PVs can also harvest the incident irradiance on the rear surface with respect to the most popular monofacial PVmodules (mo-PVs). This characteristic leads to an increase in the PV capacity density without changing the technology structure. This aspect is particularly crucial for developing the PV sector as it is a critical point in the _International Technology Roadmap for PV_[8], published by the Machinery and Equipment Manufacturers Association. Indeed, bi-PVs are technologically similar to mo-PVs, and this similarity permits the use of most of the know-how already gained in the manufacturing processes and management of mo-PVs [9; 10; 11; 12]. Compared to their monofacial counterparts, bi-PVs offer a higher power output and a competitive cost per watt, at 0.34 USD/Wp for bi-PVs and 0.32 USD/Wp for mo-PVs [13]. A confirmation of this is the study by [PERSON] et al., which examined the global levelized cost of energy (LCOE) of bi-PVs and mo-PVs in both fixed and variable tilt configurations [14; 15]. It is outlined that bi-PVs always provide the lowest LCOE. Therefore, the _International Technology Roadmap for Photovoltaic_ forecasted that bi-PVs should cover 70% of the global PV market share by 2033 [8]. However, the evaluation of the energy performance of bi-PVs appears to be much more complex than the one for mo-PVs. Such difference stands in the number of incident irradiance components that must be considered. In fact, while for mo-PVs, only the front irradiance is converted into electricity, in bi-PVs, the rear irradiance is also harvested, which introduces further complexity in the modeling. While the front irradiance depends only on sky conditions, the rear irradiance strongly depends on ground characteristics. Because of the difficulties in modeling the ground and in particular, its reflection capacity, the rear irradiance modeling encounters higher inaccuracies than the front one, as stated in [16]. This paper aims to collect the most recent findings and modeling techniques related to bi-PVs. One of the modeling techniques reviewed is used to evaluate the influences of several design parameters on the optimal deployment of a bi-PV system for a specific case study. In particular, the analysis separately considers the effects of ground reflectivity, module mounting height, and weather conditions on the incident irradiance components of a south-facing bi-PV system. In fact, by isolating each dependency on the rear incident irradiance, the comparison between monofacial and bifacial is straightforward and highly applicable, regardless of the module type or the geographical location of the application.