Open AccessArticle

Effects of Building Color, Material, and Angle on Bifacial and Transparent Solar Panels

Nagib Fahoum

and

Moshe Sitbon

Electric & Electronics Faculty, Ariel University of Samaria, Ariel 40700, Israel

Author to whom correspondence should be addressed.

Processes 2025, 13(2), 480; https://doi.org/10.3390/pr13020480

Submission received: 22 December 2024 / Revised: 30 January 2025 / Accepted: 5 February 2025 / Published: 10 February 2025

(This article belongs to the Special Issue New Challenges and Solutions to Improve Energy and Computational Efficiency in Smart Grids)

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Figure 1
Electrical model of a bifacial cell. "> Figure 2
Description of the solar radiation on the front side and the reflection of the radiation on the back side of the solar panel, neglecting diffuse irradiance. "> Figure 3
An array of panels installed at an angle on a white-coated stainless-steel background. "> Figure 4
The angle between the surfaces. "> Figure 5
RAYTECH double-glass transmittance module I–V and P–V curves [<a href="#B10-processes-13-00480" class="html-bibr">10</a>]. "> Figure 6
Reconstruction of I–V curve, which appears in [<a href="#B10-processes-13-00480" class="html-bibr">10</a>]. "> Figure 7
Reconstruction of P–V curve, which appears in [<a href="#B10-processes-13-00480" class="html-bibr">10</a>]. "> Figure 8
I–V curve for the 11 × 5 array and an irradiance of 1000 W/m2 on both sides. "> Figure 9
P–V curve for the 11 × 5 array and 1000 W/m2 irradiance on both sides. "> Figure 10
P–V curve of the 11 × 5 array with a background of white-coated stainless steel. "> Figure 11
P–V curve with a background of aluminum without a coating. "> Figure 12
P–V curve with a background of stainless steel without a coating. "> Figure 13
I–V curve when the panels were installed on a stainless-steel white surface at a 30° slope. "> Figure 14
P–V curve when the panels were installed on a stainless-steel white surface at a 30° slope. "> Figure 15
I–V curve of different backgrounds with an irradiance on the front side of 1000 W/m2. "> Figure 16
P–V curve of the various backgrounds with an irradiance on the front side of 1000 W/m2. "> Figure 17
Maximum power in relation to the albedo of the material (color). ">

Versions Notes

Abstract

Numerous studies have explored the placement of solar panels on the facades or roofs of buildings. This study investigates a new approach to estimating energy generation from transparent, double-sided solar panels integrated into the facade of an existing building, focusing on how the façade’s color influences panel performance. The most significant advantages of integrating double-sided and transparent solar panels on the sides of a building are the natural lighting provided by the sunlight entering the building and the additional energy generated when the radiation returns to the back of the panel. The light beam strikes the front panel, allowing some radiation to pass through the transparent panel to the back side, where it hits the surface. Part of the beam is then reflected toward the rear panel. The fraction of light reflected (albedo) depends on the surface’s color. We first constructed a double-sided, transparent solar panel and integrated it with MATLAB software 2024 code. The model was verified by comparing the simulation results, specifically the I–V and P–V graphs, with data from the manufacturer’s specifications. We conducted an extensive investigation into panels installed on surfaces made of different materials during each installation. This investigation aimed to understand the behavior and performance of the panels when installed on the surfaces of various materials.

Keywords:

bifacial transparent solar panel; façade of building; fraction of light reflected (albedo)

1. Introduction

Bifacial solar cells, a technology dating back to 1960, are designed to capture solar irradiance from both sides of the cell, effectively utilizing reflected sunlight from surfaces such as the ground. By leveraging the albedo, these cells can enhance solar energy absorption by up to 50%. We anticipate that 40% to 50% of solar panels sold by 2028 will utilize bifacial technology [1]. Transparent solar cells have emerged as a solution to the challenges posed by traditional photovoltaic (PV) technologies, which were initially limited to rooftops and vacant lots. The constrained space in buildings made implementing these technologies effectively and increasingly difficult. In response, researchers and scientists have turned their focus to transparent PV technologies. One promising aspect of these advancements is their potential to integrate seamlessly into windows, offering dual benefits of energy generation and innovative architectural design enhancements throughout daylight hours [2,3]. PV cells can be integrated into buildings using three primary placements: rooftops, windows, and building facades [2]. In this way, two goals can be achieved: sunlight illuminates the interior of the building, and energy is generated. Thus, researchers have explored installing photocells and double-sided transparent cells on the facade of a building, significantly impacting the building’s color reflection and directly influencing energy production. Certain colors exhibit a high albedo, enhancing energy production, as demonstrated in [4]. Accordingly, this study selected colors to test their impact on the energy production of transparent bifacial panels installed on an existing building’s facade. This research used the tables of albedo values appearing in [5,6,7]. Furthermore, placing the panels near the building’s facades significantly impacts their transparency. The more transparent the panels are, the more irradiance passes through to the panel’s rear side. Thus, a direct correlation exists between panel transparency, the albedo value of the building’s facade color, and panel energy production. Choosing a cell with higher density necessitates the consideration of transparency because of their inverse relationship, as illustrated in [3] and Equation (1).

T_{M} = (1 - D_{c}) \times T_{v}

(1)

where

T_{v}

is the transparency of the glass,

D_{c}

is the cell density, and

T_{v}

is the transparency of the glass. When installing panels on a sloped facade, according to [8], the building color affects the albedo (irradiance reflection) between surfaces, as does the angle between them. Therefore, energy production from the back side of the panels is impacted. This investigation aims to understand how specific angles affect energy production. This research presents a program in MATLAB that simulates bifacial and transparent solar panels and checks the background color effect according to the albedo tables in the literature [5,6,7]. We simulated the installation of a panel array on the front of a building without a gap to reduce the effects of scattered irradiance and reflections from other objects and tested the effect of building color mainly on the energy production that was added from the back side of the panel installed on the front of the building. Next, we tested the vertical installation of panels on a sloped facade and evaluated the effect of the reflection of the sloped facade on the energy production from the panels. The research was carried out in the following steps: First, we devised a software code to simulate a single double-sided solar cell, which could be separated based on the contribution of each side of the cell according to the electrical circuit shown in Figure 1. This approach was different from that taken in [9], which analyzed a bifacial panel using monofacial electrical models. Next, we expanded the single-cell software code to simulate the double-sided, transparent solar panel from [10]. In addition, we modified the code to simulate an array of solar panels installed on the facade of a building. The main goal of this research was to simulate panels on different color backgrounds. Therefore, we needed to project light at different intensities on the front side to examine the effect of the color of the base on the energy production, particularly on the back side of the panel. This goal was achieved by combining several parameters in the software code: the intensity of the radiation on the front side of the panel, the transparency of the panel, and the reflection of the color (i.e., albedo) from the surface on which the panel was installed. The albedo is critical because the intensity of the reflected radiation affects the energy production from the back side of the panel. This paper ends with a discussion of the results, the innovations of this study, its limitations, and improvements that could be made in the future. Table 1 presents the nomenclature used in this paper.

2. The Essence of the Problem and the Goal of This Study

2.1. Incorporating PV Cells into Buildings

The concept of nearly zero-energy buildings (NZEBs) involves enhancing the energy efficiency of the building envelope, followed by integrating renewable energy sources (RESs), such as PV systems, to meet electricity demands reliably in both existing and new buildings.

The best available method for NZEBs is the integration of transparent solar PV cells, allowing sunlight to penetrate the interior parts of the building. As reported in Section 1, the transparency of the panels directly affects the density of the cells; greater transparency means a lower cell density, which results in less energy. Therefore, for energy efficiency, double-sided transparent solar cells are a good choice, utilizing the light energy penetrating the building’s interior and returning it via the albedo to the back side of the panel.

Integrating bifacial PV modules into a building facade is a significant step in applying this relatively new technology. In addition to functioning as a renewable electricity source in its active role, such a facade decreases the building’s cooling requirements through its passive capabilities. In one study [11], the authors designed multilayer, one-dimensional dynamic thermal models of monofacial glass–back sheets and bifacial glass–glass PV modules integrated into a building facade. Given the geometry and PV technologies of the facades, as well as the weather conditions in Catania, Italy, the bifacial glass–glass PV modules yielded about 5% more energy than monofacial PV modules.

In 2013, the IEA illustrated that more than one-third of total energy consumption comes from buildings. Additionally, Xin Liang et al. [12] showed that buildings consume 40% of the world’s energy. These studies focused on how to select the type of glass or thickness of glass without considering the integration of solar panels on the glazing surface, which can hinder energy production. Therefore, to fill this gap, one study in [11] proposed an approach to determine the type of glass covering on the building and optimize the solar cell installation area on the facade to reduce the energy demand during the operation phase of buildings. The authors presented the results of a simulation performed on an existing 30-story building in Vietnam; the predicted energy generated from panels installed on four facades of the building were as follows: south side, 107.36

[\frac{KWh}{m^{2} year}]

; north side, 70.71

[\frac{KWh}{m^{2} year}]

; west side, 132.24

[\frac{KWh}{m^{2} year}]

; and east side, 131.03

[\frac{KWh}{m^{2} year}]

An integrated PV building offers the advantage of harnessing solar radiation from all sides, particularly during sunrise and sunset. The research detailed in [12], which examined the radiation intensity in Sharjah, UAE, revealed peaks between 5:00 am and 9:00 am in the east and between 3:00 pm and 7:00 pm in the west, reaching 800 W/m². This highlights the potential for energy generation from east- and west-facing facades.

The previous section emphasized the demand for integrating solar panels into the facades of newly designed buildings. This study aims to explore energy production via the installation of solar panels on existing commercial or residential buildings, some of which were constructed many years ago with facades made of concrete, stone, or marble. We identify the most efficient methods for installing solar panels on these buildings to generate green energy, and the optimal approach involves using transparent and bifacial solar panels on the facades, allowing energy generation from both sides. The challenge at hand is to develop a software module to assess the potential energy output from these panels. Maximizing energy efficiency entails generating the maximum energy from the rear side of the panel, influenced by the panel’s transparency and the building façade’s albedo, which varies with the building’s color and material. This study examines how the building’s color impacts energy production from these panels.

2.2. PV and Transparent Cell Electrical Module

Based on previous studies, we developed an electrical model for bifacial PV cells featuring two current generators and two diodes. This modeling approach simplifies the differentiation of energy production between the panel’s front and back sides [13,14,15,16]. In this study, separating the contributions of the front and back sides of the double-sided, transparent solar panel was critical. We focused on evaluating the change in the energy contribution of the panel compared to the change in the light intensity that penetrates the double-sided panel, hits the background, and returns to the back side of the panel. According to [17], manufacturers provide guidelines for constructing such models based on their specifications.

The following equations define the behavior of the solar panels:

I_{p v} = I_{p h, f} + I_{p h, r} - I_{01} [\exp (\frac{q v}{(a 1 N c K T)}) - 1] - I_{02} [\exp (\frac{q v}{a 2 N c K T}) - 1] - \frac{V_{D}}{R_{p}} .

(2)

I_{01} = \frac{(I_{s c} + K_{i} Δ T)}{\exp (\frac{(v_{o c} + K_{V} Δ T) q}{a 1 N_{c} k T}) - 1}

(3)

I_{02} = \frac{(I_{s c} + K_{i} Δ T)}{\exp (\frac{(v_{o c} + K_{V} Δ T) q}{a 2 N_{c} k T}) - 1}

(4)

I_{p h, f} = α \times (I_{s c, f} + K i \times Δ T) \times \frac{G_{f}}{G_{s}}

(5)

I_{p h, r} = α \times (I_{s c, r} + K i \times Δ T) \times \frac{G_{r}}{G_{s}}

(6)

2.3. Installing a Bifacial Transparent Panel and Studying the Effect of Color

This section examines the installation of a solar panel on a colored surface, see Figure 2 and Figure 3, and analyzes the impact of color on energy production from the panel. Our simulation utilized parameters from a RAYTECH (Hangzhou Bay New Zone, Ningbo, China) panel with the following specifications: a double-sided, transparent panel with model code BPDMJ36H(S)-215, as referenced in [10]. The transparency of these panels is 45%, and the efficiency is 12.5%. The array consisted of 115 panels, 11 in series and 5 in parallel. The software simulated their performance on surfaces mimicking building facades and systematically altered the facade color to assess its impact on energy production from these panels.

For this purpose, we adjusted Equation (6) to account for the albedo of the facade color and the effect of the transparency of the panel, yielding Equation (7) for the current generation produced by the back side of the panel.

I_{p h, r} = α (I_{s c, r} + K i \times Δ T) \frac{G f}{G s} (T r a n s p a r e n t) (A l b e d o f a c t o r)

(7)

Equation (7) is valid, provided that the panels are installed directly on the surface (β = 0) with no diffuse irradiance. According to [8], the irradiance is transferred from surface 1 to surface 2, accounting for the albedo factor, global horizontal irradiance (GHI; the amount of irradiance incident on the horizontal surface), direct normal irradiance (DNI), and diffuse horizontal irradiance (DHI), and is calculated as follows:

G_{1, 2} = (Albedo factor) DNI \frac{1 + \cos β}{2} + (Albedo factor) (GHI - DNI) (\frac{1 + \cos β}{2} - F_{i j})

(8)

F_{i j} = \frac{1 - \cos (180 ° - β)}{2}

(9)

where

β

is the angle between the surfaces and

F_{i j}

is the view factor of radiation from area A_i to area A_j. In terms of the irradiation from surface i directly to surface j, in this article, A_i is the surface area of the building, and A_j is the area of the back side of the panel, as illustrated in Figure 4. The view factor is a purely geometric quantity that is independent of heat and surface properties.

In this study, we neglected DHI because we assumed that the panel was installed directly (without a gap) on the base or front of the building; therefore, GHI = DNI. Otherwise, additional measurements or calculations would be necessary. Therefore, only DNI was considered, following Equation (7), which corresponds to (10), which is the equation for generating irradiance on the back side of a vertically installed inclined panel. Equation (10) is the current generation for the back side of the panel, combining the transparency value of the cell, the albedo factor of the base on which the panel was installed, the DNI, and the angle between two surfaces β:

I_{p h, r} = α (I_{s c, r} + K i \times Δ T) \frac{G_{f}}{G_{r}} (T r a n s p a r e n t) (A l b i d o f a c t o r) (DNI) \times 0.5 \times (1 + \cos β)

(10)

3. Simulation Results

3.1. Single-Panel Simulation

This research created a software code to simulate a solar panel, as described in [10]. Below are the simulation results for the module in [10]. Note that the radiation on the front side is always equal to the radiation on the back side. In addition, the current vs. voltage (I–V) and power vs. voltage (P–V) curves of RAYTECH were obtained under standard test conditions (STCs) when the projections were equal on both sides (Figure 5).

Figure 6 and Figure 7 show the I–V and P–V curves, respectively, from the simulation based on the STCs in [10].

3.2. Array Simulation

This section shows the simulation results for a panel array with 11 panels in series and 5 in parallel with an irradiance of 1000 W/m² on both sides. We aimed to obtain the array’s maximum power. In addition, the results are used for comparison in later sections.

Figure 8 and Figure 9 show the resulting I–V and P–V curves, respectively, where the maximum obtainable power is 11,637 W.

3.3. Array Performance on White-Coated Stainless Steel

We calculated the contribution of the back side of the 5 × 11 panel array on a building facade with white-coated stainless steel. The albedo of the white-coated stainless steel was 78.46 (i.e., albedo = 0.7846), and the transparency of the panel was 45%. The front side of the panel was exposed to different projection intensities.

According to the P–V curve in Figure 10, when the background color was a stainless-steel white coating, the maximum receivable power was 7947 W.

3.4. Array Performance on Aluminum Façade

We calculated the contribution of the back side to a 5 × 11 panel array on an aluminum facade without a coating. The albedo of the aluminum was set to 72.53%, and the transparency of the panel was 45%; the front side of the panel was exposed to different projection intensities.

Figure 11 shows that the maximum receivable power with this setup was 7759 W.

3.5. Array Performance on Stainless Steel

We calculated the contribution of the back side of a 5 × 11 panel array on a facade of stainless steel. The albedo of the stainless-steel color was set to 69.67%, and the transparency of the panel was 45%; the front side of the panel was exposed to different projection intensities.

According to Figure 12, when the background color was stainless steel without a coating, the maximum receivable power was 7671 W.

3.6. An Array of Panels on a Sloping White-Coated Stainless Steel

Installing an array of panels on a sloping stainless-steel white coating background requires the consideration of the background’s inclination. When the panels are installed at an angle to the building’s surface, the reflection of light from the background is affected. In this case, the simulation exposed the front side of the panel to different projection intensities with the panels and surfaces at an angle of 30°. Figure 13 and Figure 14 show the resulting I–V and P–V curves, where the maximum receivable power was 7780 W.

3.7. Summary of Simulation Results

Table 2 shows the simulation results related to the efficiency of the color and the overall efficiency of the panel; as mentioned in [16], the efficiency of the panel was 12.5%.

The third row in Table 2 shows the maximum power when the radiation power on the front side was 1000 W/m², and the background was generated from a material that appears in the first row. The fourth row is the percentage ratio between the maximum power obtained when the radiation on the front side had an intensity of 1000 W/m² compared to the maximum power when 1000 W/m² was irradiated from both sides.

3.8. Color Effect

Figure 15 shows the I–V curve simulation results when the irradiance on the front sides of the panel was 1000 W/m², and the following background colors were used:

1—Stainless-steel white coating.
2—Aluminum without coating.
3—Stainless-steel without coating.
4—White ceramics.
5—Red ceramics.
6—Coral concrete.
7—Concrete.

Figure 16 shows the P–V curve simulation results when the irradiance on the front sides of the panel was 1000 W/m² with the following background colors used:

1—Stainless-steel white coating.
2—Aluminum without coating.
3—Stainless-steel without coating.
4—White ceramics.
5—Red ceramics.
6—Coral concrete.
7—Concrete.

3.9. Summary Figure and Analysis of Results

The power produced was measured under an irradiance of 1000 W/m² on the panel array from both sides under STCs, and the maximum obtainable power from this panel was 11,637 W.

As summarized in Table 2 and Figure 17, we simulated a solar panel mounted on bases of different colors when the radiation intensity was 1000 W/m² on the front side of the panel. The color of the most effective background was the white-coated stainless steel; we obtained a maximum power of 7947.53 W, which is 68.29% of the maximum power of the panel. For the background made of aluminum without a coating, we obtained a maximum power of 7759 W, which is 66.67% of the maximum power of the panel. For a background made of stainless steel without a coating, we obtained a maximum power of 7671 W, which is 65.91% of the maximum power of the panel. For a background made of white ceramic material, we obtained a maximum power of 7153.19 W, which is 61.14% of the maximum power of the panel. For a background made of coral concrete material, we obtained a maximum power of 6557.89 W, which is 56.35% of the maximum power of the panel. For a background made of red ceramics, we obtained a maximum power of 6529.67 W, which is 56.111% of the maximum power of the panel. For a background made of concrete material, we obtained a maximum power of 6743.77 W, which is 58% of the maximum power of the panel.

In addition to the above results, we carried out a test on a panel installed on a white-coated stainless-steel background at an inclination of 30° when the radiation on the front side was 1000 W/m². The maximum power was 7779.6 W, which means that it decreased by 2.4% compared to the power obtained without an angle. Therefore, an angle between the panels and the surface yields less energy.

4. Summary and Conclusions

Many studies have investigated the issue of transparent solar panels; for example, the authors in [18] investigated the installation of transparent panels in agricultural sites and the effects of various parameters on agriculture, and another study [19] used the solar-harvesting method to improve energy performance.

This work investigated and tested the installation of double-sided, transparent solar panels on backgrounds of different colors without reference to the diffuse irradiance. Additionally, we investigated and tested the effect of the background color on the production of energy from these panels, which enabled us to estimate the amount of energy that could be obtained from these panels. This study took into account two important points: light rays need to penetrate the building for lighting purposes and efficient energy production, and for this purpose, double-sided and transparent panels were chosen. Therefore, we needed to consider several important factors, including the transparency of the panels (which were also affected by the cell density) and the effect of albedo on energy production. As a result, we designed software that could simulate the installation of an array of solar panels on a surface, changing the surface color and considering the common materials and colors of buildings. The power produced by the panels was evaluated, taking into account the albedo, transparency of the panel, and the tilt angle. The simulations were accurate in terms of installing a panel directly without a gap on the facade of an existing building, and we were able to estimate the maximum energy that could be received.

Author Contributions

Methodology, N.F. and M.S.; Validation, N.F.; Writing—original draft, N.F. and M.S. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

The original contributions presented in this study are included in the article. Further inquiries can be directed to the corresponding author.

Conflicts of Interest

The authors declare no conflict of interest.

References

IRENA. Future of Solar Photovoltaic: Deployment, Investment, Technology, Grid Integration and Socio-Economic Aspects; A Global Energy Transformation Paper; International Renewable Energy Agency: Abu Dhabi, United Arab Emirates, 2019. [Google Scholar]
Zeng, Q.; Chen, J.; Ni, J.; Ai, Q.; Wang, Z.; Zhai, R.; Xu, P.; Ma, C.; Wang, P. A Research on Design and Evaluation of BIPV. In Proceedings of the 5th International Conference on Electric Utility Deregulation and Restructuring and Power Technologies, Changsha, China, 26–29 November 2019. [Google Scholar]
Pellegrino, M.; Flaminio, G.; Graditi, G. Testing and Standards for New BIPV Products. In Proceedings of the IECON 2013-39th Annual Conference of the IEEE Industrial Electronics Society, Vienna, Austria, 10–13 November 2013; pp. 8127–8132. [Google Scholar]
Kotak, Y.; Gul, M.S.; Muneer, T.; Ivanova, S.M. Investigating the Impact of Ground Albedo on the Performance of PV Systems. In Proceedings of the CIBSE Technical Symposium, London, UK, 16–17 April 2015. [Google Scholar]
Lin, C.H.; Han, C.Y.; Lui, C.P. A Comparison of the Albedo of Asian Building Materials in Visible and UVB Regions; IEEE: Piscataway, NJ, USA, 2011. [Google Scholar]
Taha, H.; Sailor, D.; Akbari, H. High-Albedo Materials for Reducing Building Cooling Energy Use; Energy and Environment Division, Lawrence Berkeley Laboratory, University of California: Berkeley, CA, USA, 1992. [Google Scholar]
Prado, R.T.A.; Ferreira, F.L. Measurement of Albedo and Analysis of Its Influence on the Surface Temperature of Building Roof Materials. Energy Build. 2005, 37, 295–300. [Google Scholar] [CrossRef]
Cha, H.L.; Bhang, B.G.; Park, S.Y.; Choi, J.H.; Ahn, H.K. Power Prediction of Bifacial Si PV Module with Different Reflection Conditions on Rooftop. Appl. Sci. 2018, 8, 1752. [Google Scholar] [CrossRef]
Bouchakour, S.; Valencia-Caballero, D.; Luna, A.; Roman, E.; Boudjelthia, E.A.K.; Rodríguez, P. Modelling and Simulation of Bifacial PV Production Using Monofacial Electrical Models. Energies 2021, 14, 4224. [Google Scholar] [CrossRef]
Ningbo Raytech New Energy Materials Co., Ltd. Double Glass 45% Transmittance Solar Panels 215-230W Double Glass Transparent Modules. Available online: https://www.raytech-energy.com (accessed on 14 August 2024).
Nguyen, Q.; Luong, D.; Pham, A.; Truong, Q. Developing an Optimization Model of Solar Cell Installation on Building Facades in High-Rise Buildings—A Case Study in Viet Nam. GMSARN Int. J. 2021, 15, 44–49. [Google Scholar]
Radwan, A.; Mahmoud, M.; Olabi, A.-G.; Rezk, A.; Maghrabie, H.M.; Abdelkareem, M.A. Thermal Comparison of Mono-Facial and Bi-Facial Photovoltaic Cells Considering the Effect of TPT Layer Absorptivity. Int. J. Thermofluids 2023, 18, 100306. [Google Scholar] [CrossRef]
Hong, D.; Ma, J.; Man, K.L.; Wen, H. Prediction of I-V Characteristics for Bifacial PV Modules via an Alpha-Beta Single Double-Diode Model. In Proceedings of the 2022 IEEE Energy Conversion Congress and Exposition, Detroit, MI, USA, 9–13 October 2022; pp. 1–5. [Google Scholar]
Ahmed, E.M.; Aly, M.; Mostafa, M.; Rezk, H.; Alnuman, H.; Alhosaini, W. An Accurate Model for Bifacial Photovoltaic Panels. Sustainability 2023, 15, 509. [Google Scholar] [CrossRef]
Olabi, A.; Ghani Kamal, M.; Taha, E. Renewable Energy: Solar, Wind and Hydropower, 1st ed.; Elsevier: Amsterdam, The Netherlands, 2023. [Google Scholar]
Olabi, A.G.; Wilberforce, T.; Elsaid, K. Large Scale Application of Carbon Capture to Process Industries—A Review. J. Clean. Prod. 2022, 362, 132300. [Google Scholar] [CrossRef]
Vergura, S. Simulink Model of a Bifacial PV Module Based on the Manufacturer Datasheet. In Proceedings of the 18th International Conference on Renewable Energies and Power Quality (ICREPQ’20), Granada, Spain, 1–2 April 2020. [Google Scholar]
Cho, J.; Park, S.M.; Park, A.R.; Lee, O.C.; Nam, G.; Ra, I.-H. Application of Photovoltaic Systems for Agriculture: A Study on the Relationship between Power Generation and Farming for the Improvement of Photovoltaic Applications in Agriculture. Energies 2020, 13, 4815. [Google Scholar] [CrossRef]
Katepalli, A.; Wang, Y.; Shi, D. Solar harvesting through multiple semi-transparent cadmium telluride solar panels for collective energy generation. Sol. Energy 2023, 264, 112047. [Google Scholar] [CrossRef]

Figure 1. Electrical model of a bifacial cell.

Figure 2. Description of the solar radiation on the front side and the reflection of the radiation on the back side of the solar panel, neglecting diffuse irradiance.

Figure 3. An array of panels installed at an angle on a white-coated stainless-steel background.

Figure 4. The angle between the surfaces.

Figure 5. RAYTECH double-glass transmittance module I–V and P–V curves [10].

Figure 6. Reconstruction of I–V curve, which appears in [10].

Figure 7. Reconstruction of P–V curve, which appears in [10].

Figure 8. I–V curve for the 11 × 5 array and an irradiance of 1000 W/m² on both sides.

Figure 9. P–V curve for the 11 × 5 array and 1000 W/m² irradiance on both sides.

Figure 10. P–V curve of the 11 × 5 array with a background of white-coated stainless steel.

Figure 11. P–V curve with a background of aluminum without a coating.

Figure 12. P–V curve with a background of stainless steel without a coating.

Figure 13. I–V curve when the panels were installed on a stainless-steel white surface at a 30° slope.

Figure 14. P–V curve when the panels were installed on a stainless-steel white surface at a 30° slope.

Figure 15. I–V curve of different backgrounds with an irradiance on the front side of 1000 W/m².

Figure 16. P–V curve of the various backgrounds with an irradiance on the front side of 1000 W/m².

Figure 17. Maximum power in relation to the albedo of the material (color).

Table 1. Nomenclature.

Abbreviation	Definition
$T_{M}$	Percentage transparency of module
$D_{c}$	Cell density
$T_{v}$	Transparency of glass
$I_{0}$	Reverse saturation current of bypass diode
$q$	Electron charge constant (1.60217646 × 10⁻¹⁹ C)
$N_{C}$	Number of cells
$k$	Boltzmann constant (1.3806503 × 10⁻²³ J/K)
$T$	Temperature of the p-n junction (K)
a	Diode ideality constant
$I_{S C}$	Short circuit current
$V_{O C}$	Open circuit voltage
$G_{f}$	Irradiance received by front side of panel
$G_{r}$	Irradiance received by rear side of panel
$V_{D}$	Voltage drop across the circuit
$R_{S}$	Series resistance
$I_{0, 1}$	First diode’s reverse saturation current
$I_{0, 2}$	Second diode’s reverse saturation current
$I_{s c, f}$	Short circuit current on front side
$I_{s c, r}$	Short circuit current on rear side
$α$	Measurement error rate
$I_{p h, f}$	Generation current of the front side of the panel.
$I_{p h, r}$	Generation current of the rear side of the panel
$Δ T$	Temperature difference between the experimental temperature T and standard temperature (25 °C)
Albedo	Fraction of light that a surface reflects
GHI	Global horizontal irradiance
DNI	Direct normal irradiance
DHI	Diffuse horizontal irradiance
β	Angle between two surfaces
$G_{1, 2}$	Intensity of the radiation transferred from surface 1 to surface 2
$F_{i j}$	View factor of radiation from area A_i to area A_j

Table 2. Simulation results efficiency of the color and the overall efficiency.

Material and Color	White Ceramics	Red Ceramics	Aluminum Without Coating	Stainless-Steel Without Coating	Concrete	Coral Concrete	Stainless-Steel White Coating
Albedo	0.531	0.331	0.7253	0.6967	0.3–0.4	0.34	0.7846
Power [W]	7153.19	6529.67	7759	7671.09	6433.63–6743.77	6557.89	7947.53
Percentage of maximum power	61.14%	56.111%	66.67%	65.91%	55–58%	56.35%	68.29%
General efficiency of the panel in [16]	7.64%	7.03%	8.333%	8.23%	6.8–7.24%	7.04%	8.5369%

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Fahoum, N.; Sitbon, M. Effects of Building Color, Material, and Angle on Bifacial and Transparent Solar Panels. Processes 2025, 13, 480. https://doi.org/10.3390/pr13020480

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Fahoum N, Sitbon M. Effects of Building Color, Material, and Angle on Bifacial and Transparent Solar Panels. Processes. 2025; 13(2):480. https://doi.org/10.3390/pr13020480

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Fahoum, Nagib, and Moshe Sitbon. 2025. "Effects of Building Color, Material, and Angle on Bifacial and Transparent Solar Panels" Processes 13, no. 2: 480. https://doi.org/10.3390/pr13020480

APA Style

Fahoum, N., & Sitbon, M. (2025). Effects of Building Color, Material, and Angle on Bifacial and Transparent Solar Panels. Processes, 13(2), 480. https://doi.org/10.3390/pr13020480

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