## 1 Introduction
Standard deviations of 30% of backlighting may occur with low mounted modules [14]. However, the effect can be reduced (ranging 2.8-4.1%) by increasing GCH [14], which links the positive effect of increasing GCH to its intrinsic reduction in back non-uniformity. In particular scenarios, not all the optimal system parameters can be achieved. This is the case of industrial-like rooftops, where roof structural resistance limits module height, as it would increase both dynamic and static loads (wind-pressure loads and PV weight structure, respectively), intrinsically augmenting the rear non-uniformity. This can produce a considerable reduction in bifacial contribution due to the self-shading factor being considerably high (12.3-20%), even in specially designed structures [17]. The supporting elements (frames, beams, purlins, and piles) can obstruct backside irradiance about 20% in fixed tilted installations [18]. As a possible countermeasure, cold roofs with high albedo have been proposed [19]. As high albedo implies less radian energy translated into a local increment of ambient temperature, bPV modules will operate at lower local temperatures and higher back illumination. An albedo increment of 0.1 would imply an addition of 4.5% of energy production [19]. A recent research has tested a nanomaterial with extremely high albedo and thermal emittance (96% and 80%, respectively), which would imply an additional cooling of 20 W/m\({}^{2}\) (compared to sand) and an additional cell photocurrent of up to 6.42 mA/cm\({}^{2}\)[20]. Nevertheless, a notable increase in albedo could not necessarily imply a significant increase in production since non-uniform illumination induced by mounting structure can considerably reduce bifacial contribution [21]. From a potential bifacial power gain (BPG) of up to 23% at high albedo, it could be reduced to 5% just for the unevenness introduced by support structures [21]. Additionally, wide dispersion on measured backside irradiance has been observed to depend on both the sensor [22] and module position (within an array of modules) [23; 24]. The reported non-uniformity, as defined by IEC 60904-1-2 [1], can be as high as 35% in outdoor conditions [24]. Even though the presence of non-uniform back illumination should rarely produce hotspot issues in bPV modules [22], there is at least one reported case of a considerable increase in local temperatures (+30 \({}^{\circ}\)C) caused by the torque tube of an horizontal single-axis tracker (HSAT) [25]. This last fact highlights the importance of paying special attention to the role of mounting structures when dealing with bPV installations. In order to investigate bifacial performance in the complex scenario of industrial-like rooftops, different tests were carried out. They include a comparison of a bifacial module with two different conventional PV devices (oriented at the optimal monofacial tilt, 30\({}^{\circ}\)) and a comparison of two bPV modules with slightly different backlight obstructions. Accurate simulation tools for bPV modules, which can evaluate their power generation potential under different environmental conditions, are essential for predicting the energy yield of bPV-based solar generators and optimizing their performance [26]. In terms of the electrical model, it is common practice to adapt conventional models for bPV applications. One approach is to incorporate a current source into PV-equivalent circuits to account for photogenerated currents from backside irradiance, resulting in four-, five-, or six-parameter models [27]. Another proposal is to use two conventional models in parallel, one for each surface [28; 29]. To fully represent the multiphysics behavior of bPV modules, it is necessary to integrate the electrical model with thermal and optical considerations [30]. Experimental data, like those presented in this study, are critical to evaluate and validate these models or develop new ones.