###### Abstract
For example, the bifacial gain of field-installed bPVs is limited to below 4% due to inhomogeneous rear reflection, which is significantly lower than what is achievable under ideal conditions [10; 11; 25]. The intensity of rear incident light on bPVs is typically influenced by factors such as the albedo of the rear reflector, the distance between the module and the rear reflector, the angle of rear incident light, the installation angle of bifacial PV, and other variables [3; 19; 23; 26]. Thus, the rear surface and installation conditions should be taken into careful consideration during the design of PV power plants with bPVs. In field-installed bPVs, negligible current mismatch induced by non-uniform rear irradiation commonly takes place due to the elongated distance between bifacial cells and a rear surface (D\({}_{\text{RR}}\)). Self-shading by PV cells and non-uniform reflectance from a rear surface can be compensated during the extended path to reach the rear side of the bPVs [5; 27]. As the fraction of reflected light to reach the rear side of bPVs increases proportionally with the D\({}_{\text{RR}}\), theoretical simulations and experimental results indicate that a 1 m of D\({}_{\text{RR}}\) is high enough to minimize the deviation of rear incident light among bifacial cells in bPVs. However, a short distance between the rear surface and bPVs gives rise to non-uniform rear reflection issues when integrated into BIPV systems. Non-uniform rear reflection is an inherent challenge in bPVs equipped with a nearby specular surface [23]. The adverse effects of non-uniform rear incident light result in power loss and local heating of PV cells. Bifacial PV cells with non-uniform rear incident light may restrict the operating current, leading to energy generation losses and potential safety hazards through cell heating [10; 24; 28]. Particularly, current mismatch among cells is expected to occur more frequently in a BIPV with bPVs due to a shorter D\({}_{\text{RR}}\). [PERSON] et al. observed that the deviation of rear incident light exceeds 200 W/m\({}^{2}\) in a bPV with 10 cm of D\({}_{\text{RR}}\) under standard test conditions [5]. Simulation studies also indicate that the non-uniformity of rear incident light exceeds 50% when the D\({}_{\text{RR}}\) is less than 50 cm [25]. Additionally, non-uniform rear incident light can cause localized heating of bifacial cells, raising their temperature by more than 15 \({}^{\circ}\)C [24]. Although the bypass diodes are applied in bPVs to maximize the power output during periods of non-uniform rear illumination, the continuous current flow through the bypass diode might cause leakage in currents and pose fire issues due to a massive reverse current [24; 29; 30; 31]. Most BIPVs replacing roofs, curtain walls, and spandrels with solar panels are normally installed close to the envelope of buildings, where the D\({}_{\text{RR}}\) is small (less than 10 cm) [24; 32]. Moreover, controlling the albedo and D\({}_{\text{RR}}\) of the rear surface is nearly impossible, increasing the likelihood of unevenly distributed rear incident light [23]. Consequently, BIPVs incorporating bPVs may experience uneven rear incident light, leading to a diminished energy generation and to an increase in reliability issues. To address issues arising from non-uniform rear incident lights in BIPVs with bPVs, a rear reflector has been introduced. The double glass-structured BIPV comprising of bPVs and a rear reflector enhances energy generation and minimizes heat dissipation from buildings, significantly improving the energy efficiency of buildings with them. Furthermore, selective and Bragg reflectors provide a BIPV with bPVs with the functionality of a glass window and recycle unabsorbed photons [33; 34; 35]. These reflectors redirect some of the photons that strike the gaps between cells to the rear side of the bPVs, thereby increasing their efficiency.