Thermal Impacts of Solar Panels on Environment Surrounded by Medium- and High-Rise Buildings †
Department of Architecture, National Taipei University of Technology, Taipei 10608, Taiwan
*
Author to whom correspondence should be addressed.
†
Presented at the 2025 IEEE 5th International Conference on Electronic Communications, Internet of Things and Big Data, New Taipei, Taiwan, 25–27 April 2025.
Eng. Proc. 2025, 108(1), 48; https://doi.org/10.3390/engproc2025108048
Published: 22 September 2025
(This article belongs to the Proceedings of 2025 IEEE 5th International Conference on Electronic Communications, Internet of Things and Big Data)
Abstract
By employing computational fluid dynamics (CFD) software (Ansys Fluent), we examined the thermal effects of vertical solar panels on the south-facing facades of mid-rise (50 m) and high-rise (100 m) buildings in a 5 × 5 idealized urban environment. Four configurations were analyzed in this study: no installation, evenly distributed, concentrated, and panels on both sides. Vertical solar panel installations were affected by building temperatures and pedestrian-level thermal environments. In the leeward streets of central buildings, pedestrian-level temperatures progressively increased by row, with the even distribution showing significant heat accumulation. For 100 m buildings, the average temperature under the even distribution configuration increased from 35.6 °C (no panels) to 39.5 °C (a difference of 3.9 °C, approximately 10.96%).
1. Introduction
Under the rapid development of urban economies and technologies, extreme global climate events are becoming severe. The Paris Agreement (COP21) of 2015 proposed limiting global temperature rise to within 2 °C above pre-industrial levels, with efforts to further constrain the global temperature rise to 1.5 °C. More than 130 countries have pledged to achieve “net-zero emissions by 2050”, emphasizing the importance of renewable energy and driving nations to actively seek alternative energy sources to reduce carbon emissions and conserve energy [1].
Solar energy, as a key renewable resource, requires sufficient space for the installation of solar panels [2]. Common configurations include rooftop, ground-mounted, and vertical installations. Ground-mounted solar farms, particularly those located on agricultural land or wastelands, require considerable land resources, indirectly affecting agricultural production and ecosystems [3]. In densely populated urban areas with limited land availability, utilizing high-rise building facades for vertical solar panel installations presents a viable alternative. Current research on urban solar panel installations focuses on factors such as wind pressure, material properties, and cooling efficiency [4]. However, there have been scarce studies examining the impact of vertical solar panels on building surface temperatures, thermal and cooling loads, and urban microclimate. High-rise and high-density urban developments tend to concentrate heat, influencing urban ventilation and overall environmental conditions. Therefore, it is essential to investigate whether excessive heat generated by solar panels worsens the urban heat island (UHI) effect and potentially harms ecosystems and human health.
In this study, we employed computational fluid dynamics (CFD) simulations in an idealized urban setting to assess the thermal effects of vertical solar panel installations on mid-rise (50 m) and high-rise (100 m) buildings. Four installation configurations were examined: no installation, evenly distributed panels, concentrated panels, and panels installed on both sides of the building. The result provides guidance and recommendations to support the sustainable integration of solar energy in high-rise urban developments.
2. Literature Review
2.1. Wind and Thermal Environment
Taiwan’s rapid urbanization and limited land resources have driven the construction of high-rise and high-density buildings. Heat concentration on the buildings has significantly affected urban microclimates, ventilation, and environmental quality. Anthropogenic heat emissions disrupt urban airflow, while artificial materials absorb solar radiation, preventing buildings from reflecting longwave radiation [5]. The subjective perception of the thermal environment in surrounding areas plays a crucial role in thermal comfort, influenced by temperature, humidity, wind speed, radiant heat, and air quality [6]. According to the 2021 Annual Energy Outlook, the residential building sector in the United States was the largest consumer of electricity. Maintaining optimal thermal comfort enhances quality of life, work efficiency, and public health [7]. Integrating thermal comfort considerations into building performance modeling significantly impacts energy efficiency and comfort levels, ultimately informing optimal design decisions. While solar panel installations are widely recognized as a future energy solution, they contribute to heat accumulation, complicating efforts to improve building environments and thermal comfort.
The configurations of urban buildings influence how surfaces absorb solar radiation and how surrounding winds flow. Other key factors influencing airflow include wind speed, wind direction, building configurations, and street dimensions. Optimal ventilation on development sites while considering wind transmission to adjacent areas is critical. A research result showed that a ventilation rate of 30% enabled optimal airflow.
In urban development projects, ventilation on the sites and adjacent areas must be considered for spatial environmental optimization. Using the internationally recognized Beaufort scale as an assessment standard, wind effects on ground-level objects and the urban environment were investigated to improve urban microclimates.
2.2. Correlation Between Heat Generation and Efficiency of Solar Panel
Temperature, wind patterns, humidity, and solar radiation are important factors in urban planning and design. Therefore, for human comfort and energy consumption, solar energy technology must be integrated carefully. Solar panels function by absorbing solar energy and converting it into photovoltaic (PV) electricity [8]. However, this technology has limitations. While solar panels absorb approximately 80% of the incident radiation, their conversion efficiency remains relatively low. Only a fraction of the absorbed energy is transformed into electricity, while the majority is converted into heat, increasing panel temperatures and further reducing energy conversion efficiency [9].
Building facades account for 60–80% of a building’s total surface area. Minimizing heat absorption on exterior surfaces contributes to lowering surface temperatures and mitigating the urban heat island (UHI) effect [10,11]. Vertical solar panels expand the available area for renewable energy utilization in buildings and enhance solar power generation efficiency under specific conditions. The amount of solar incident on a building’s facade depends on solar altitude and azimuth angles, which vary on season and geographic location [12]. South-facing walls receive more solar radiation than north-facing walls because the solar trajectory in the Northern Hemisphere casts shadows on north-facing walls for extended periods. Additionally, the upper sections of building facades receive more solar radiation than the lower sections due to their broader sky exposure, resulting in greater solar panel efficiency in elevated areas.
Vertically installed solar panels reduce the surface area of buildings exposed to direct sunlight, thereby lowering cooling demands. This is beneficial for high-rise buildings in tropical and subtropical regions [13]. In high-sunlight areas, such as Hong Kong, vertical solar panels improve energy efficiency, reduce cooling requirements, and decrease overall building energy consumption [14]. Consequently, in building designs, thoughtful solar panel layouts and orientations must be incorporated to optimize solar energy capture and conversion efficiency while also accounting for local climatic conditions to ensure panel durability and performance in harsh environments.
3. Research Design
3.1. Urban Model
The architecture in this study was configured based on previous studies. An idealized urban model with 25 buildings arranged in a 5 × 5 grid was used in this study. The area was 270 × 310 m, with street widths set at 40 m along the Y-axis (A) and 30 m along the X-axis (B). The building mass was calculated with each structure having a fixed length and width of 30 m (Figure 1). Kaohsiung, located in southern Taiwan, experiences prolonged and stable sunlight conditions and has adopted high-density urban planning, making it optimal for maximizing solar panel energy efficiency. We focused on medium-rise (50 m) and high-rise (100 m) buildings in Kaohsiung to assess solar panel performance.
3.2. Boundary Conditions and Meteorological Parameters
We used ANSYS Fluent v18 fluid dynamics simulation software to conduct three-dimensional spatial simulation and analysis. The 2019–2023 CODIS climate data were obtained from the Kaohsiung Sanmin station. Statistical data for the past five years showed that the dominant wind direction was north-northeast (54%), and the average temperature was 28.53 °C (Table 1).
3.3. Simulation Scenarios: Eight Groups
By using SketchUp 2023 lighting simulation software, we analyzed the relationship between the solar incidence angle and building mass in the Kaohsiung area. The shadow area on the buildings was 30% of the building height, thus the area available for solar panel installation on the building facade was 70% (Figure 1). Based on the “Kaohsiung City Building Solar Photovoltaic Facility Installation Regulations”, the solar panel area on each facade must be at least 50%. For example, for the 50 m building, the formula for calculating the vertical solar panel area was as follows: 50 m (building height) × 30 m (building width) × 0.7 (illuminated area) × 0.5 (installation area). We constructed four configuration scenarios: no installation, concentrated distribution, distribution on both sides, and evenly distributed (Table 2). We examined the wind–thermal field differences and urban canyon changes for high-rise buildings with vertical solar panels at pedestrian (1.5 m), mid-building level (25 m), and rooftop level (50 m) (Figure 1).
4. Results and Discussion
4.1. Surface Temperature of Vertical Solar Panels
For the 50 m building, the average surface temperature of the solar panels ranged as follows: L-4 (41.3 °C) > L-3 (39.2 °C) > L-2 (38.9 °C). For the 100 m building, the average surface temperature of the solar panels was as follows: H-4 (36.9 °C) > H-3 (33.8 °C) > H-2 (32.8 °C). The building facade in the 50 m building with no installation of solar panels showed an average temperature of 59.3 °C. Since the reflectivity of cement is relatively low and easily absorbs heat energy, the installation of solar panels adds a layer to the facade structure, reducing the amount of direct solar radiation entering the building’s surface. However, this leads to heat accumulation at the intersection and rear street canyon. Due to the relatively low building height in the configuration of the 50 m building, there was less mutual shading between buildings, causing a temperature increase. Compared with the configuration of the 100 m building, the configuration led to higher temperatures, while the heat distribution on both sides and concentrated distribution configurations were similar. The average distribution configuration enabled the solar panels to receive ample sunlight, thereby increasing thermal generation. High temperatures were directly proportional to the amount of sunlight exposure. The heat was concentrated in the lower part of the solar panels as shown in Table 3.
4.2. Temperature Variation in Pedestrian Layer (Z = 1.5 m)
With the installation of vertical solar panels, the average temperature at the pedestrian layer was measured as follows: L-4 41.5 °C (increase by 9.78% compared with no solar panels) > L-3 38.5 °C (increase by 1.85%) > L-2 38.0 °C (increase by 0.52%) > L-1 37.8 °C. The presence of solar panels significantly influenced the temperature in the street canyon on the leeward side of the building, resulting in the accumulation of warm air at the pedestrian level surrounding the structure. When comparing the average temperature in the street canyon pedestrian layer with those of the average distribution configuration and the no installation configuration, the former showed severe heat accumulation as the first to the third street canyons showed a temperature increase of 9.78, 9.67, and 12.52% (Table 4).
The average temperature of the 100 m building (H) at the pedestrian layer was as follows: H-4 (39.5 °C) (increase by 10.96% compared with no solar panels) > H-3 (38.8 °C) (increase by 8.77%) > H-2 (38.7 °C) (increase by 8.71%) > H-1 (35.6 °C). In the second row of the street canyon, the average temperature at the pedestrian layer was as follows: H-4 (40.1 °C) (increase by 9.26% compared with no solar panels) > H-2 (39.2 °C) (increase by 6.81%) > H-3 (38.8 °C) (increase by 5.72%) > H-1 (36.7 °C). These results indicate that high-rise buildings, due to their larger shading areas caused by mutual shading effects, contributed to a more pronounced accumulation and stagnation of hot air around the structure. This phenomenon was intensified by low surrounding wind speeds, which trapped heat at the pedestrian level, particularly within street canyon areas. The first row of the street canyon, under the average distribution configuration, exhibited the most significant temperature change, with an increase to 40.1 °C, showing a 3.4 °C increase.
4.3. Pedestrian Layer (Z = 1.5 m) Temperature Variation Analysis
The average temperature of the 50 m building (L) at a height of Z = 25 m compared with the temperature without solar panels was as follows: L-4 36 °C (increase by 1.98%) > L-2 = L-3 35.5 °C (increase by 0.57%) > L-1 35.3 °C. The average temperature of the middle floor of the building after installing solar panels was slightly higher than that of the configuration without solar panels. However, the impact was smaller than that of the pedestrian layer. Although the average temperature increase behind the building in the centralized configuration was similar to that in the two-side distribution configuration, the heat was concentrated on both sides of the building, and the average configuration showed the most obvious temperature difference.
When vertical solar panels were installed on a 100 m building at a height of 25 m, the average temperature increase, compared with the configuration without solar panels was measured as follows: H-4 (33.6 °C) (increase by 3.7%) > H-2 (32.8 °C) (increase by 1.23%) > H-3 (32.6 °C) (increase by 0.61%) > H-1 32.4 °C. The average temperature increase and temperature in the middle section of the sub-row street valley from high to low was as follows: H-4 (33.9 °C) (increase by 2.72%) > H-3 (33.4 °C) (increase by 1.21%) > H-2 (33.3 °C) (increase by 0.9%) > H-1 33.0 °C. When no solar panels were installed at the section height, the temperature of the evenly distributed configuration at this height increased slightly, and the distribution configuration on both sides showed the least impact (Table 5).
5. Conclusions and Recommendations
Solar panels installed in evenly distributed configurations on 50 and 100 m buildings significantly increased overall temperatures. The pedestrian layer and street canyons showed notable temperature rises, with heat accumulation. The street canyons on the leeward side were gradually heated due to thermal accumulation and limited air circulation. The 50 m building showed higher street valley temperatures in the evenly distributed and unstructured configurations, with increases of 0.78% in the first row, 9.67% in the second row, and 12.52% in the third row. This configuration allowed heat to spread extensively, increasing the overall street valley temperature significantly. In contrast, heat accumulation in centralized and two-side distribution configurations in 50 and 100 m buildings was dispersed. The temperature difference between the centralized distribution and no-panel configurations was relatively small. The 50 m building exhibited a larger temperature rise than the 100 m building. Despite this, the overall temperature remained higher than the no-panel configuration. The two-side distribution configuration showed similar temperature patterns in the 50 and 100 m buildings, except for the sub-row next to the 50 m building. Heat accumulation in centralized and two-side configurations was concentrated along the building street valley, where weak airflow at the pedestrian level trapped heat, creating an uncomfortable thermal environment. As building height increased, the thermal environment temperature rose. After vertical solar panels were installed in the 50 and 100 m buildings, temperatures in the second-row street valley exceeded those in the front-row street valley in both configurations. The 50 m building exhibited higher temperatures, and faster wind blew to the building, which dissipated heat effectively. In contrast, the 100 m building retained accumulated heat, intensifying thermal impact. Both Dang Pai Street Valley and Sub Pai Street Valley were affected, with a significant temperature increase at the pedestrian level. By installing vertical solar panels in high-rise buildings, building energy efficiency can be increased as the panels incorporate multiple layers of surface coverings. The configurations help reduce excess heat, improving overall thermal performance.
Author Contributions
Conceptualization, Y.-M.S. and P.-C.Y.; methodology, Y.-M.S.; software, P.-C.Y.; validation, Y.-M.S. and P.-C.Y.; formal analysis, P.-C.Y.; investigation, P.-C.Y.; re-sources, Y.-M.S.; data curation, P.-C.Y.; writing—original draft preparation, P.-C.Y.; writing—review and editing, Y.-M.S.; visualization, Y.-M.S.; supervision, Y.-M.S.; project administration, Y.-M.S.; funding acquisition, Y.-M.S. All authors have read and agreed to the published version of the manuscript.
Funding
Thanks for the funding of the National Science Technology Council, Taiwan, R.O.C. (Contract No.: NSTC 113–2221–E–027–025).
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
No new data were created or analyzed in this study. Data sharing is not applicable to this article.
Conflicts of Interest
The authors declare no conflict of interest.
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Figure 1.
Ideal urban configurations.
Table 1.
Sanmin station meteorological parameters (2019–2023) from CODIS.1.
| Item | Content |  |
| Station Selection | KaohsiungC0V700Sanmin | |
| 2019 to 2023 Annual Average Wind Speed | 1.94/s | |
| 2019 to 2023 Annual Prevailing Wind Direction | NNE (54%) | |
| 2019 to 2023 Annual Average Temperature | 28.53 °C |
Table 2.
Boundary conditions and meteorological parameters.
| 50 m building | L-1 No installation | L-2 Concentrated distribution | L-3 Distribution on both sides | L-4 Evenly distributed |
 Solar panels |  |  |  |  |
| 100 m building | H-1 No installation | H-2 Concentrated distribution | H-3 Distribution on both sides | H-4 Evenly distributed |
 Solar panels |  |  |  |  |
Table 3.
Surface temperature of vertical solar panels.
50 m building (L) vertical solar panel surface temperature  | |||
| L-1 | L-2 | L-3 | L-4 |
 |  |  |  |
100 m building (H) vertical solar panel surface temperature  | |||
| H-1 | H-2 | H-3 | H-4 |
 |  |  |  |
Table 4.
Temperature variation in pedestrian layer (Z = 1.5 M).
| L-1 | L-2 | L-3 | L-4 |
 |  |  |  |
| H-1 | H-2 | H-3 | H-4 |
 |  |  |  |
 | |||
Table 5.
Temperature variation at mid-level of building (z = 25 m).
| L-1 | L-2 | L-3 | L-4 |
 |  |  |  |
| H-1 | H-2 | H-3 | H-4 |
 |  |  |  |
 | |||
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MDPI and ACS Style
Su, Y.-M.; Yang, P.-C. Thermal Impacts of Solar Panels on Environment Surrounded by Medium- and High-Rise Buildings. Eng. Proc. 2025, 108, 48. https://doi.org/10.3390/engproc2025108048
AMA Style
Su Y-M, Yang P-C. Thermal Impacts of Solar Panels on Environment Surrounded by Medium- and High-Rise Buildings. Engineering Proceedings. 2025; 108(1):48. https://doi.org/10.3390/engproc2025108048
Chicago/Turabian StyleSu, Ying-Ming, and Po-Chun Yang. 2025. "Thermal Impacts of Solar Panels on Environment Surrounded by Medium- and High-Rise Buildings" Engineering Proceedings 108, no. 1: 48. https://doi.org/10.3390/engproc2025108048
APA StyleSu, Y.-M., & Yang, P.-C. (2025). Thermal Impacts of Solar Panels on Environment Surrounded by Medium- and High-Rise Buildings. Engineering Proceedings, 108(1), 48. https://doi.org/10.3390/engproc2025108048
