From 'big energy consumer' to 'energy factory', how does photovoltaic curtain wall reshape the future cityscape?

When it comes to photovoltaic curtain walls that can generate electricity, many people's first reaction is whether it will be incompatible with the original architectural style and destroy the overall aesthetics of the building. In fact, this is not the case. Current photovoltaic curtain wall technology has matured, not only can it perfectly integrate with various architectural styles, but it can also improve the energy utilization efficiency of buildings through early intelligent design, achieving a harmonious unity of aesthetics and power generation functions.

Taking cadmium telluride photovoltaic curtain walls, which are currently the most widely used in the construction industry, as an example, the light transmittance can be adjusted according to the building's lighting needs, balancing power generation efficiency while ensuring the building's transparency. Taking Longyan Energy's cadmium telluride power generation glass as an example, the light transmittance can be flexibly adjusted between 0% and 80%. Jiaxing Xiuzhou Science and Technology Service Center, as the first high-rise building project in China and even the world to achieve the LOW-E glass effect with photovoltaic glass, uses 40% cadmium telluride thin-film translucent power generation glass, with a total installed capacity of about 150KW. It not only meets the lighting needs of the entire building, but also continuously provides green energy.

In terms of color and texture, current BIPV technology products have been able to achieve the appearance of traditional building materials, and can flexibly customize patterns, colors, and grid sizes. Qingyuan Olympic Sports Center, the main venue of the Guangdong Provincial Games, uses gray aluminum-imitation cadmium telluride photovoltaic building materials on the roof, and the shape and size of each piece are different. While ensuring style unity, it can also have higher power generation efficiency. Similarly, there is the aluminum-imitation photovoltaic curtain wall of Datong Future Energy Museum in Shanxi, and the aluminum-imitation photovoltaic curtain wall of Haikou Mobile Building. This customized design makes the photovoltaic curtain wall no longer detached from architectural aesthetics, but an organic part of it.

In terms of thermal performance, the cadmium telluride power generation curtain wall can reduce the internal temperature of the building. On the one hand, cadmium telluride components all contain transparent conductive oxide film layers, namely TCO films with low radiation and low reflectivity. The infrared transmittance of TCO glass at 780~2500nm is about 60%, while that of ultra-white glass is 90%, meaning that more infrared rays are reflected, and infrared rays are the main factor in indoor radiation temperature increase, thus reducing the increase in indoor heat. On the other hand, after photoelectric conversion, the cadmium telluride component converts part of the solar energy into electrical energy. According to the law of conservation of energy, less light energy is transmitted through cadmium telluride. Moreover, cadmium telluride glass is black, which can absorb most of the sunlight and convert it into heat energy, and this heat energy is then taken away by external convection, thus reducing indoor heat transfer.

In terms of safety, the cadmium telluride photovoltaic curtain wall strictly follows the relevant professional requirements of the construction industry from design, construction to operation and maintenance stages. Therefore, the photovoltaic curtain wall can effectively resist extreme weather. When designing BIPV, it is based on the relevant standards stipulated in "General Specification for Building Energy Efficiency and Renewable Energy Utilization" GB55015-2021 and local policies. The compliance is ensured in the initial design stage, and it is closely combined with electrical designers, following the requirements of "Electrical Design Specification for Solar Photovoltaic Glass Curtain Walls" JGJ/T365-2015 throughout the process to ensure the safety and reliability of the photovoltaic curtain wall grid connection and wiring system. In the operation and maintenance stage, the performance of BIPV will be continuously monitored and data analyzed. There is a mechanism for rapid response and effective handling of any faults.

Regarding the economic analysis of photovoltaic curtain walls, their investment return characteristics deserve in-depth discussion. There is a common misconception in the current market: some companies overemphasize the high initial investment cost of photovoltaic curtain walls, while failing to fully assess their life-cycle economic value. Taking the south facade project of a commercial building in Beijing as an example, using a 20% light transmittance cadmium telluride power generation glass curtain wall scheme, compared with the traditional glass curtain wall, its incremental investment cost can be recovered through power generation revenue in about 8 years. It is worth noting that the design service life of photovoltaic curtain wall systems is usually more than 25 years, and the actual operating cycle is often longer. This means that after the initial investment is recovered, the system can still maintain a net profit period of more than 16 years, continuously generating significant economic benefits. This long-term and stable return characteristic makes photovoltaic curtain walls a strategic green building investment choice.

Currently, photovoltaic curtain walls mainly have three installation forms: exposed frame, semi-concealed frame, and point-supported. The exposed frame uses traditional aluminum alloy frames to wrap photovoltaic components. When subjected to external loads such as gravity load and wind load, the load can be transmitted to the concrete structure through aluminum alloy columns to ensure structural stability and strong wind resistance, suitable for office buildings, commercial buildings and other conventional curtain wall needs. The semi-concealed frame structure can be divided into vertical exposed and horizontal concealed and vertical concealed and horizontal exposed forms, combining the characteristics of exposed frame and concealed frame. The exposed frame enhances wind resistance, and the hidden frame reduces visual clutter, meeting diverse styling needs while effectively reducing light obstruction. The point-supported type consists of panels, point support devices, and support structures. It has high light transmittance, visual transparency, and can be combined with artistic shapes to meet the needs of different building structures and decorative effects.

It is necessary to see that the current photovoltaic curtain wall technology still faces problems such as the lack of industry technical standards and insufficient market awareness, especially the lack of management methods in the most critical fire acceptance. From the perspective of building photovoltaic standards, electricity, structure, and heat preservation have been covered, but safety performance indicators such as fire prevention are lacking. In the future, it is necessary to continuously improve the construction of the photoelectric building standard system, coordinate the fields of construction, electricity, and fire protection, and clarify the requirements for fire prevention and structural safety. In addition, it is necessary to strengthen the interaction and communication between the construction and photovoltaic industries, continuously deepen the understanding of photoelectric building materials products by construction industry professionals, and adopt a complementary approach of group standards, industry standards, and national standards to promote the large-scale and high-quality advancement of BIPV market applications.

Driven by the "dual carbon" goals, this new type of green building technology, photovoltaic curtain walls, with its dual attributes of "power generation + building", can significantly reduce the energy consumption of buildings, and because of its customizable characteristics, it can be highly integrated with building styles. It is gradually becoming an "invisible driving force" in the future urban landscape, transforming urban buildings from "energy consumers" to "energy providers", and making "zero-carbon aesthetics" a collective memory of the new era.