Understanding the Key Applications of Photovoltaic Products in Building-Integrated Photovoltaics (BIPV)

I. Building-Integrated Photovoltaics (BIPV): A New Trend in Building Energy Efficiency

Nowadays, building energy efficiency and the utilization of renewable energy are receiving increasing attention, with Building-Integrated Photovoltaics (BIPV) being a popular area. Simply put, BIPV integrates photovoltaic power generation products with buildings, allowing buildings to generate electricity while fulfilling various functional needs. This achieves energy self-sufficiency, reduces environmental impact, and aligns perfectly with current green and environmentally friendly concepts. From April 1, 2022, the "General Code for Building Energy Efficiency and Renewable Energy Utilization" has been officially implemented, which includes numerous regulations on the application of solar energy systems in buildings. These regulations play a significant guiding role in the development of BIPV.

 

II. Basic Regulations for Solar Energy Systems in Buildings

(I) Requirements for Solar Energy Systems in New and Existing Buildings

The installation of solar energy systems in new buildings has become a mandatory requirement. This is because incorporating solar energy systems during the planning and construction phases of new buildings is more convenient and cost-effective. By installing solar energy systems, solar energy can be utilized to power buildings, provide domestic hot water, and even heating and cooling, fully leveraging the role of this clean energy source.

For existing buildings, if adding or modifying a solar energy system is desired, a safety review of the building structure must be conducted first. This is because the structure of existing buildings may have been in use for some time, and a review ensures that the building structure remains safe and reliable after the addition of the solar energy system. After all, nobody wants their house to become unsafe because of installing a solar energy system.

(II) Comprehensive Utilization and Design Requirements for Solar Energy Systems

Solar energy systems should achieve comprehensive utilization throughout the year. In different regions, climatic conditions, actual needs, and applicable conditions vary, so the functions of the solar energy system should be arranged reasonably according to local conditions. For example, in areas with abundant sunshine and cold winters, in addition to power generation, solar energy can be used for heating; in the hot south, the demand for cooling and power generation may be greater.

Furthermore, the design of building-integrated photovoltaic application systems must be completed synchronously with the building design. This ensures that the solar energy system and the building are perfectly integrated, not only without affecting the building's aesthetics but also making the overall building more harmonious. At the same time, when installing solar energy systems on buildings, the daylighting standards of adjacent buildings must not be reduced. No one wants their installation of solar energy equipment to block their neighbor's sunlight and affect their normal life.

(III) Safety Requirements and Monitoring and Measurement of Solar Energy Systems

The safety of solar energy systems is paramount; every aspect, from structure and electricity to fire prevention, cannot be neglected. The enclosure components composed of solar collectors or photovoltaic panels must not only meet the power generation function but also meet the safety and functionality requirements of the corresponding enclosure components. For example, they must be windproof, waterproof, and provide insulation and heat preservation.

Buildings with installed solar energy systems must also have safety protection measures in place. On the one hand, this is for the safety of installation and maintenance personnel; on the other hand, it is to prevent damage to solar collectors or photovoltaic panels and subsequent component falls that could injure people. This is not a trivial matter; every year, there are incidents of injuries caused by high-altitude falling objects, so protection must be in place.

In addition, the solar energy system should also monitor and measure some key parameters, such as power generation, hot water output, and energy consumption. By monitoring and measuring these parameters, the operating status of the solar energy system can be better understood, problems can be identified and adjusted in a timely manner, and energy utilization efficiency can be improved.

(IV) Special Technical Measures for Solar Thermal Utilization Systems

Solar thermal utilization systems face different problems in different regions, so corresponding technical measures must be adopted. In cold regions, antifreeze measures should be taken to prevent pipes and equipment from freezing; in humid regions, condensation should be prevented to avoid damage to equipment or mold growth due to condensation. Overheating should also be prevented, as solar collectors can reach very high temperatures under strong sunlight. Without measures, this may affect equipment lifespan or even cause safety problems. Waterproof, lightning protection, hail protection, wind resistance, earthquake resistance, and electrical safety measures are also essential. For example, in areas with frequent thunderstorms, if lightning protection measures are not in place, the solar energy system is easily damaged by lightning strikes.

III. BIPV Product Classification and Requirements

(I) Basic Requirements and Classification Methods for BIPV Products

BIPV products must meet both electrical and building requirements. Electrically, they must comply with standards such as IEC 61215 and IEC 61730, which specify the electrical and safety performance requirements of photovoltaic products. In terms of building requirements, they must have good mechanical safety performance and fire resistance, as well as a certain degree of heat insulation and sound insulation to ensure the comfort and safety of the building.

There are several ways to classify BIPV products. According to whether they contain glass, they can be divided into BIPV components with glass and BIPV components without glass. BIPV components with glass can be further subdivided according to installation methods and structure. From the installation method, there are those installed at an angle on the building roof or enclosure structure, and those attached to the building to form an additional external functional layer; structurally, there are different types such as single-pane glass plus polymer structures and double-glazed laminated glass structures. This detailed classification helps us better understand the characteristics and applicable scenarios of different BIPV products.

(II) Detailed Classification of BIPV Components with Glass

BIPV components with glass can be divided into five categories according to their installation method. The first category is photovoltaic components installed on the exterior of the building enclosure structure at an angle of less than 75°, with safety protection to prevent falling. This installation method is common in sloped roof buildings, utilizing roof space for power generation while ensuring safety through safety protection.

 

The second category is photovoltaic components installed on the interior of the building enclosure structure at an angle of less than 75°, serving as part of the building enclosure structure. This is like using photovoltaic components as part of the wall or roof, not only generating electricity but also acting as an enclosure structure, such as insulation and heat preservation. The third category is photovoltaic components installed on the exterior of the building enclosure structure at an angle greater than or equal to 75° and less than or equal to 90°, with rear safety protection to prevent falling into the building interior. This installation method is common on the exterior walls of some high-rise buildings, achieving both building aesthetics and power generation, while safety protection ensures the safety of the building interior.

The fourth category is photovoltaic components installed on the interior of the building enclosure structure at an angle greater than or equal to 75° and less than or equal to 90°, serving as part of the building enclosure structure. This installation method allows for better integration with the interior space of the building, meeting the functional needs of the building.

The fifth category involves the installation of photovoltaic components on buildings, forming an additional external functional layer relative to the building's envelope. For example, installing a layer of photovoltaic components on the exterior wall of a building does not affect the original building structure while adding power generation and other functions, such as shading.

 

In addition to classification by installation method, classification by structure is also possible. For example, Type A is a single-pane glass + polymer structure BIPV component, which is relatively lightweight and potentially lower in cost; Type B is a double-glazed laminated glass structure BIPV component, which may offer better safety and thermal insulation performance. Different structures of BIPV components vary in performance, cost, and applicability, requiring selection based on specific needs in practical applications.

Differences in Test Items under Different Standards

Different standards have different requirements when testing BIPV products. Standards such as 2PfG 2796, EN 50583-1, and IEC 62109-3 share common basic requirements, all needing to meet both electrical and building requirements, but differ in specific test item details, sample requirements, and judgment criteria.

 

The two standards 2PfG CH 0029 and 2PfG 2796 have the same structure, but differ in the reference standards for building-related test items. 2PfG CH 0029 refers to domestic standards, while 2PfG 2796 refers to European or international standards. This requires manufacturers and testing institutions to clearly understand the requirements of different standards during testing to ensure that products comply with relevant regulations.

IV. Interpretation of Related Concepts

BIPV and Related Building Component Concepts

BIPV stands for Building-Integrated Photovoltaics. It closely integrates photovoltaic power generation with buildings, transforming buildings from mere energy consumers into energy producers. Building photovoltaic components are photovoltaic power generation products with building component functions, such as photovoltaic curtain walls and photovoltaic skylights. A photovoltaic curtain wall is a curtain wall containing photovoltaic components capable of power generation. It not only serves as an enclosure and decoration like a regular curtain wall but also utilizes solar energy for power generation. The same applies to photovoltaic skylights, which provide lighting while generating electricity.

 

Building curtain walls consist of panels and a supporting structural system. They can have a certain degree of displacement relative to the main structure or have their own deformation capacity without bearing the loads of the main structure. Component-type building curtain walls involve on-site installation of columns, beams, and various panels, while unit-type curtain walls are prefabricated complete curtain wall structural units in factories and then directly installed on the main structure. These two types of curtain walls have their own advantages and disadvantages and are used in different building projects.

 

Significance of Understanding Concepts for Practical Applications

Understanding these concepts is crucial for the practical application of BIPV. For example, a clear understanding of the difference between photovoltaic curtain walls and ordinary curtain walls allows for better selection of curtain wall types during building design and construction. If the goal is to achieve green energy efficiency and enhance the building's technological feel, photovoltaic curtain walls might be a better choice; however, if the focus is solely on decorative and enclosure functions, ordinary curtain walls may suffice.

Understanding the concept of building photovoltaic components helps in making more targeted product selections. Different types of photovoltaic components vary in performance, installation methods, and costs. Only by understanding these aspects can the most suitable product be chosen based on the building's actual needs, achieving optimal economic and energy efficiency.

 

V. Summary: Development and Challenges of BIPV

Building-integrated photovoltaics have broad development prospects. With continuous technological advancements, the performance of BIPV products will improve, and costs will gradually decrease. In the future, we may see more buildings adopting BIPV technology to achieve energy self-sufficiency and contribute to addressing climate change.

However, BIPV currently faces some challenges in its development. From a technological perspective, although the efficiency of BIPV products is constantly improving, further enhancement is needed to meet greater energy demands. Furthermore, deeper research is needed into the integration of different BIPV products with buildings to ensure that power generation does not compromise the building's aesthetics or functionality.

From a market perspective, the relatively high cost of BIPV products limits large-scale promotion. Moreover, consumer awareness of BIPV technology is still low, with many people unfamiliar with this emerging technology, affecting market acceptance.

To promote the development of BIPV, concerted efforts from governments, enterprises, and research institutions are needed. Governments can introduce more policy support, such as subsidies and tax incentives, to reduce enterprise costs and increase consumer purchasing enthusiasm. Enterprises should increase R&D investment, continuously innovate technology, improve product performance, and reduce costs. Research institutions should strengthen basic research to provide theoretical support for the development of BIPV technology.