Facade photovoltaic potential explodes! Latest research: Potential in some urban areas exceeds rooftops by 1.5 times!

Against the backdrop of accelerating global energy transformation, building-integrated photovoltaics (BIPV) is extending from the "rooftop era" to the "facade era."A recent research result published in the interdisciplinary journal Nexus of Cell Press by Professor Yan Jinyue's team from the Hong Kong Polytechnic University, in collaboration with the University of Tokyo and Peking University Shenzhen Graduate School, reveals the potential of facade photovoltaics compared to rooftop photovoltaics.This discovery undoubtedly brings new perspectives and insights to the development of the BIPV industry.

Based on three-dimensional urban building footprint data and multi-source meteorological spatio-temporal data, the study comprehensively assessed the building facade and rooftop photovoltaic potential in the core areas of 120 cities worldwide through advanced shadow simulation technology.The results show that,the potential of facade photovoltaics is approximately 68.2% of that of rooftop photovoltaics on average, while in some urban areas, the potential of facade photovoltaics even exceeds that of rooftop photovoltaics by 1.5 times.This data undoubtedly provides a new direction for BIPV industry practitioners: In addition to traditional rooftop photovoltaics, facade photovoltaics also has enormous development value.

The advantages of facade photovoltaics lie in their ability to fully utilize the facade space of buildings, especially in cities with dense populations and limited rooftop space.The facades of buildings in these cities often have a larger surface area than the roofs, providing more possibilities for the installation of photovoltaic components. In addition,facade photovoltaics can also effectively reduce the urban heat island effect, improve the urban microclimate, and enhance the overall environmental quality of the city.From an aesthetic point of view,carefully designed facade photovoltaic systems can also blend with the appearance of buildings, enhancing the visual effect of the city landscape.

Solar radiation calculation in a three-dimensional building environment

Behind the 68.2% average revealed by the research data lies the deep evolutionary logic of modern urban architecture.With the global urbanization rate exceeding 56%, "vertical cities" composed of high-rise buildings have become the mainstream form.Taking typical CBDs such as Hong Kong's Central and Shanghai's Lujiazui as examples, their glass curtain wall area can reach 8-10 times the roof area, and they generally have the physical characteristic of receiving solar radiation on the east and west facades all day long. More importantly,the light transmittance of new photovoltaic curtain walls using cadmium telluride photovoltaic components can now be flexibly customized, achieving 10%-18% power generation efficiency while maintaining the architectural aesthetics, which transforms the facade space, traditionally considered a "low-efficiency area," into a calculable energy asset.。

Comparison of cadmium telluride photovoltaic components with different light transmittance

Actual effect of translucent photovoltaic curtain wall

Actual effect of opaque photovoltaic curtain wall

Technological breakthroughs are reconstructing the value chain of photovoltaic curtain wallsUnlike the single-dimensional power generation function of rooftop photovoltaics, facade photovoltaic systems, through the integrated innovation of "photovoltaics + building envelope," create a business model with multiple superimposed benefits. For example, the curved photovoltaic curtain wall project at Beijing Daxing International Airport not only achieves an annual power generation of 2 million kWh but also reduces air conditioning load by 5%, reduces noise pollution by 3 decibels, and reduces building operating costs by 12%. This synergistic effect of "power generation-energy saving-environmental protection" increases the internal rate of return (IRR) of BIPV projects from 8% in the traditional model to over 15%, completely changing the economic assessment system of photovoltaic investment.

Global scale estimation framework for building-integrated facade and rooftop photovoltaic potential

BIPV potential of four types of three-dimensional urban spatial forms

The market potential distribution shows significant regional characteristics. The study found that,the potential for facade photovoltaics in urban agglomerations around 35° north latitude generally exceeds that of rooftops, and the winter facade power generation in places like Chicago and Beijing is even 80% higher than that of rooftops.This is due to the diffuse reflection enhancement effect formed by high-rise buildings in seasons with low solar angles.

The dual drivers of policy orientation and cost curves are opening up a trillion-dollar market space.The EU's new building directive (EPBD) mandates that all new public buildings must integrate photovoltaic systems after 2027, while China's 14th Five-Year Plan for BIPV development clearly sets a target of exceeding 30 GW of installed capacity by 2025. At the same time, the Price of cadmium telluride thin-film modules, which are frequently used in facade photovoltaic curtain walls, has decreased significantly in the past few years,This has shortened the payback period for incremental investment in commercial building facade renovations to 6-8 years. Industry estimates show that the renovation market for existing glass curtain wall buildings in China alone reaches 2.3 trillion yuan, while the globally developable facade resources are 1.8 times that of rooftops.

Comparative analysis of BIPV in the central areas of 120 cities worldwide

For BIPV industry practitioners, this research result undoubtedly has important enlightening and reference value. First, it reminds us to examine the application space of BIPV technology from a broader perspective, not only focusing on the development of rooftop photovoltaics but also deeply exploring the potential of facade photovoltaics. Second, to formulate differentiated photovoltaic technology promotion strategies for different urban areas based on their characteristics and needs, so as to achieve optimal resource allocation. Finally, to strengthen interdisciplinary cooperation and innovation, promote the continuous progress and industrial upgrading of BIPV technology, and contribute more wisdom and strength to sustainable urban development.

In this building skin revolution, data does not lie—those companies that dare to break through the mindset of rooftop thinking and deeply cultivate the value of facades will ultimately occupy the strategic commanding heights in the grand narrative of urban carbon neutrality. After all, when every square meter of curtain wall becomes a "building cell" that generates electricity, the city itself will transform into a vibrant energy body. This may be the true starting point of the next golden twenty years for the BIPV industry.