Building facade photovoltaic potential has long been underestimated: An assessment analysis of BIPV potential in ten megacities in China

With the global pursuit of sustainable development and carbon neutrality goals, solar energy, as a clean and renewable energy source, is receiving unprecedented attention. In China, with the acceleration of urbanization and the continuous growth of energy demand, building-integrated photovoltaic (BIPV) systems, as an efficient way to utilize solar energy, are gradually becoming an important way to solve urban energy problems.

Graphical Abstract

Recently, the Ye Bin team from the School of Environmental Science and Engineering, Southern University of Science and Technology, published a research paper titled "Energy-economy-environment evaluation of building-integrated photovoltaic considering facade factors for representative megacities in China" in Applied Energy, a top journal in the field of engineering technology. This research developed a comprehensive assessment model for building-integrated photovoltaic (BIPV) systems to evaluate the energy-saving and carbon-reduction potential of solar energy resources and BIPV in ten megacities in representative climatic regions of China. This study innovatively evaluated the power generation potential of building-side facade photovoltaic systems using multi-dimensional images and three-dimensional building footprint methods. In addition, the coupling and interconnection of building-integrated photovoltaic systems and electric vehicles were explored to evaluate the role of electric vehicles in reducing the peak-to-valley difference of the power grid.

Copy the following paper link to your browser to access it or click on "Read the original article" at the end of the article to view the paper:

https://authors.elsevier.com/a/1ks0t15eifFubw

Based on the research paper published by the Ye Bin team from the School of Environmental Science and Engineering, Southern University of Science and Technology, in the Applied Energy journal, this article conducts an in-depth assessment and analysis of the BIPV potential in ten megacities in China, aiming to provide valuable reference and inspiration for industry practitioners.

Research Framework Diagram

As one of the world's largest energy consumers, China faces enormous pressure to reduce carbon emissions. To address this challenge, the Chinese government has proposed a series of climate mitigation paths, aiming to gradually transform the energy structure through the promotion of renewable energy. BIPV systems, as an innovative model that combines photovoltaic power generation with buildings, can not only provide a clean power supply but also effectively reduce building energy consumption and carbon emissions. However, due to differences in geographical location, climate conditions, building types, and other factors in different cities, the power generation potential of BIPV systems varies significantly. Therefore, this study aims to conduct a comprehensive assessment of the BIPV potential in ten megacities in representative climatic regions of China through multi-dimensional images and three-dimensional building footprint methods, providing scientific basis for urban planners and decision-makers.

The study shows that the annual average power generation potential of rooftop photovoltaics (RPV) in the ten cities ranges from 14.19 TWh (Lhasa) to 108.92 TWh (Shanghai), which can cover 29.1%-63.2% of the city's electricity demand. Among them, high-latitude cities (such as Harbin and Urumqi) significantly improve power generation efficiency by optimizing the roof tilt angle (average increase in irradiation absorption by 24.8%). For example, the Harbin RPV system can meet 43.6% of local electricity demand, becoming an important option for energy self-sufficiency in northern cities.

Solar radiation values are below the optimal installation surface for BIPV on each surface

The potential of building facade photovoltaics (FPV) has long been underestimated. The study shows that the south-facing facade, due to its high irradiation intensity (average 978.8 kWh/m²/year), has a power generation efficiency of nearly 60%-80% of RPV. Taking Beijing as an example, its high-rise buildings are dense, and the proportion of south-facing FPV area reaches 25%, and the annual power generation can be increased by 59.77%. However, the north-facing facade has poor economic efficiency due to insufficient irradiation (average 454.5 kWh/m²/year) and needs to be optimized in layout in combination with building morphology.

Due to differences in climate zones, site-specific installation strategies are needed:

• Cold regions (Harbin): RPV is the main focus, with optimal roof efficiency under low-angle sunlight in winter.
• Hot summer and warm winter regions (Guangzhou): FPV has strong supplementary capabilities, and the south-facing facade can alleviate the peak electricity demand in summer.
• Plateau regions (Lhasa): The highest irradiation intensity in the country (over 2000 kWh/m²/year), but low building density, requires refined development.

With the popularization of electric vehicles in various cities, their electricity consumption accounts for 6.39%-16.46% of the total power generation. The study found that the synergistic effect of BIPV-EV can significantly improve the proportion of self-generated electricity from building-integrated photovoltaics. Taking Urumqi as an example, the absorption capacity of electric vehicles has reduced the surplus electricity of distributed systems by 13.81%. This shows that electric vehicles, as a flexible power load, can effectively absorb the surplus electricity generated by the BIPV system, thereby reducing the surplus power ratio and grid back-selling ratio of the power system.

Building facade angle area of ten cities

Impact of BIPV system on environmental carbon emissions in ten cities

From the perspective of energy security, BIPV systems can significantly improve the proportion of renewable energy in cities and reduce dependence on traditional energy sources. From an economic perspective, although the initial investment of BIPV systems is high, with technological advancements and cost reductions, their economic benefits are gradually becoming apparent. In particular, rooftop photovoltaic (RPV) systems and south-facing facade photovoltaic systems, due to their better power generation potential and lower power generation costs, have better economic performance. From an environmental perspective, the promotion and use of BIPV systems can significantly reduce the carbon emission intensity of cities and make important contributions to achieving carbon neutrality goals.

Policy and technical recommendations: Breaking through the bottleneck of large-scale application

Policy level: Mandatory standards and market-oriented incentives go hand in hand

• New buildings: Mandatory requirements for BIPV coverage (e.g., rooftop ≥50%, south-facing facade ≥30%).
• Financial instruments: Provide 15%-20% installation subsidies for FPV projects and pilot carbon credit trading.

Technical level: Material innovation and digital empowerment

• Photovoltaic building materials: Develop lightweight, adjustable transmittance FPV products that adapt to glass curtain walls and irregularly shaped buildings.
• Digital twins: Based on 3D GIS models, simulate the power generation efficiency of BIPV in different climate zones and optimize installation schemes.

The large-scale application of BIPV depends not only on technological advances but also on the linkage of policies, markets, and urban planning. The analysis of the ten cities shows that RPV is currently the most economically viable option, while the potential of FPV needs to be combined with building design and material innovation. In the future, through the construction of a "BIPV+EV+smart grid" ecosystem, megacities in China are expected to take the lead in achieving the goal of "zero-carbon buildings" and provide a model for energy transformation in high-density cities around the world.

Information source: Applied Energy