How can Building-Integrated Photovoltaics (BIPV) make green buildings even greener?

I. Building-Integrated Photovoltaics: A "New Partner" for Green Buildings

Currently, the global community advocates for environmental protection, and the construction industry is following suit, with more and more green buildings appearing around us. Among numerous green building technologies, Building-Integrated Photovoltaics (BIPV) technology is particularly eye-catching. It's like a building's "energy assistant," converting solar energy into electricity, meeting the building's own power needs, reducing carbon emissions, promoting energy conservation in buildings, and even allowing excess electricity to be connected to the grid. This has significant meaning for China's development of green buildings. Today, let's take a closer look at the application of BIPV in green buildings.

 

II. What is Building-Integrated Photovoltaics?

BIPV mainly applies solar power generation technology to the construction field. Simply put, it uses photovoltaic components as the core component, utilizing the photovoltaic effect to convert the sun's energy into electricity that we can use in our daily lives. Then, these electrical components are combined with other electrical equipment, such as photovoltaic inverters and controllers, to ultimately achieve the purpose of supplying power to the building. This not only makes power supply more stable but also reduces the consumption of power energy from power plants, alleviates our electricity burden, and achieves the goal of environmental protection and energy saving.

 

As our national economy improves, people use more and more electrical equipment, and the demand for electricity is also increasing. In this situation, the widespread application of photovoltaic power generation technology is particularly important. It can provide us with a more comfortable living environment and contribute to environmental protection.

 

III. Design Principles of Building-Integrated Photovoltaics

(1) Meeting Building Applicability Requirements

When designing building-integrated photovoltaics, we must first consider the location of the building. We need to understand the local geographical location, climate, and solar energy resource distribution, which are key factors in determining whether BIPV design can be used. For example, BIPV is more suitable in areas with abundant sunshine. At the same time, we must also examine the surrounding environmental conditions of the building to see how much solar energy the building can receive. If there are many tall buildings around that block sunlight, it may not be suitable to install BIPV.

(2) Meeting Building Structural Requirements

The structure of the photovoltaic components themselves must be stable and safe. For example, if the local wind is strong, we must consider whether the photovoltaic components can withstand such a large wind load. The fixing and connection method of the components is also important and must be ensured to be sufficiently safe. This requires calculating the structure of the connection point and conducting multiple tests to see if it can function normally under various weather conditions and unexpected situations. If the connection is not firm, the photovoltaic components may fall in case of strong winds or other disasters, which would be dangerous.

(3) Meeting Building Aesthetic Requirements

The use of photovoltaic components brings new opportunities and challenges to building design. During design, if BIPV can be cleverly used, it can make the building more vibrant. Integrating the concept of energy saving and environmental protection into building design can also allow the building to better integrate with nature. For example, some buildings design photovoltaic components into unique shapes or match the building's colors harmoniously, making the building look both beautiful and technologically advanced.

(4) Meeting Building Energy-Saving Requirements

During the use of BIPV components, it is necessary to avoid problems caused by solar cell heating. Because if the battery heats up severely, it may increase new energy consumption, which runs counter to the purpose of energy saving. Therefore, it is necessary to adopt reasonable and effective measures, such as good heat dissipation design, to solve this problem.

 

IV. Advantages of Building-Integrated Photovoltaics

(1) Make Full Use of Space and Save Land Resources

In some large cities, land resources are very precious. BIPV can use the roofs and curtain walls of buildings to generate electricity without occupying additional land, thus avoiding the waste of land resources. Imagine if every building could use its roof and curtain wall to generate electricity, how much land could be saved!

(2) Reduce Infrastructure Installation

Compared with traditional power generation methods, building photovoltaic power generation does not require the installation of too much other infrastructure. This not only saves installation costs but also reduces construction time and difficulty.

(3) Reduce Building Losses and Improve Utilization Rate

BIPV can reduce building losses and improve building utilization. This is very helpful for building energy-efficient cities. For example, through photovoltaic power generation, buildings can reduce their reliance on traditional energy, reduce energy consumption, and thus reduce the losses of buildings in the process of energy use.

(4) On-site Electricity Use and Discharge, Saving Power Grid Investment

BIPV can achieve on-site electricity use and discharge, saving investment in power station transmission grids within a certain distance. This is because it does not need to transmit electricity to a distant place, reducing transmission losses and costs.

(5) Increase Power Supply and Reduce Cooling Load

Generally, photovoltaic arrays are installed on the south-facing roofs and walls for better solar energy absorption. It not only provides sufficient electricity but also reduces the indoor cooling load. In summer, when sunlight shines on the photovoltaic components, it converts into electricity while blocking some heat from entering the room, making the room cooler and reducing the use of air conditioners and other equipment, further saving energy.

(6) Innovative Improvement of Building Appearance

BIPV can improve the appearance of buildings in an innovative way. By reasonably designing the shape, color, and installation method of photovoltaic components, buildings can look more unique and modern.

(7) Centralized Control System for Convenient Management

Building photovoltaic power generation can centralize power control, maintenance, and other operating systems within the building. This makes management more convenient, and staff can more easily monitor and maintain the entire power generation system.

(8) Clean and Environmentally Friendly, Enhancing the Quality of the Building

The photovoltaic power generation system is a very clean and environmentally friendly system. It is noiseless during operation and does not emit pollutants or fuel. This is not only good for the environment but also enhances the overall quality of the building. Living in such a building, people can enjoy a quieter and healthier living environment.

 

V. Application of Building-Integrated Photovoltaics in Green Buildings

(1) Application on Building Roofs

Flat Roof Installation: For existing buildings with flat roofs, there are different methods for installing photovoltaic arrays. A common method is to fix the angle of the photovoltaic modules, which is determined by calculating the annual solar radiation angle in the region and considering various factors. This method is simple to install and maintain, and the investment cost is relatively low. However, for better utilization of solar energy, a more intelligent design scheme is now available. This involves installing an angle adjustment module consisting of a motor-driven servo motor (or stepper motor) for the photovoltaic modules. This module can automatically drive the photovoltaic modules to adjust their angles according to the light conditions throughout the year and the changes in the solar altitude angle throughout the day, allowing them to better receive sunlight and improve power generation efficiency.

 

Sloped Roof Installation: When installing photovoltaic modules on sloped roofs, south-facing roofs are the best choice. Typically, the roof and solar panels are parallel to each other. However, in actual installation, to achieve optimal power generation efficiency, it may be necessary to adjust the installation angle appropriately. The photovoltaic power generation installation requirements for sloped roofs are similar to those for flat roofs, except for the installation direction. The optimal installation direction for sloped roofs is due south, or slightly south of due south. When setting up a photovoltaic power generation system on the roof, it is important to ensure that it is compatible with the various functions of the building and does not cause conflicts. When selecting photovoltaic modules, it is necessary to combine the actual electricity consumption and economic benefits, obtaining the highest return with the lowest cost to provide the building with sufficient and reliable electricity.

 

(II) Application in Building Curtain Walls

With the development of green buildings, the application of BIPV in building curtain walls is also increasing. Curtain walls are an important part of buildings and are common in large shopping malls, libraries, swimming pools, and other public buildings. Previously, when selecting materials for curtain walls, semi-transparent glass was mostly used, which enhances aesthetics and ensures indoor lighting. However, the energy-saving effect of curtain walls is not very good. Now, applying BIPV to building curtain walls can solve this problem. Transparent double-glazed photovoltaic modules can be used as curtain wall materials, which allows power generation in the curtain wall space without affecting the appearance of the wall or indoor lighting.

 

In addition, BIPV can also be applied to building facades and shading parts. When selecting photovoltaic modules, it is necessary to make reasonable choices based on the usage requirements of the building curtain wall. Generally, the cost of roof materials is higher than that of indoor buildings. During design, to avoid conflicts with the building structure, it is best to design and construct the photovoltaic power generation system and the building structure simultaneously. Separate construction may affect the overall construction progress and waste energy resources. Simultaneous construction, however, embodies the concept of green construction.

In some buildings, the structural materials of the curtain wall can be replaced with photovoltaic power generation materials and equipment, allowing for better application of solar panels. This not only achieves the effect of building shading but also provides power to the building while shading, achieving energy saving. Moreover, installing building sunshades does not affect the overall progress of the project; installation can be done after building construction, saving installation costs and shortening the installation cycle, giving full play to the advantages of green and energy-saving buildings.

VI. Energy-Saving and Environmental Protection Functions of Photovoltaic Building Integration

The photovoltaic system does not have any harmful effects on the environment during operation. It is noiseless and does not emit harmful gases or solid waste. Taking the photovoltaic power generation project in Haikou City, Hainan Province, China, as an example, it can provide at least 859,100 kWh of environmentally friendly electricity annually. Compared with thermal power generation, it can reduce the burning of 309.5 tons of coal annually and significantly reduce the emission of various air pollutants, including a reduction of 821.64 tons of carbon dioxide emissions and 34 tons of sulfur dioxide emissions. This has a significant positive impact on China's energy conservation, environmental protection, and economic and social development.

 

VII. Summary: The Future of Photovoltaic Building Integration is Promising

With the rapid economic and social development of China, the construction industry is also making continuous progress, with more and more buildings developing towards green buildings. The application of photovoltaic building integration technology in green buildings not only meets the daily electricity needs of buildings but also embodies the concept of energy saving and environmental protection. With so many advantages, it can play an important role in building roofs and curtain walls, and is also very environmentally friendly, making it truly worthy of vigorous promotion and application. It is believed that in the future, BIPV technology will become increasingly mature, and its application will become increasingly widespread, making our buildings greener, more environmentally friendly, and more energy-efficient.