Analysis of Differences Between BIPV Modules and Conventional PV Modules, and Their Testing Methods

Driven by the "dual carbon" goals, the application scenarios of photovoltaic technology continue to expand. Building Integrated Photovoltaics (BIPV), as an innovative model, is increasingly gaining market favor. Compared to conventional PV modules, BIPV modules not only serve a power generation function but are also integrated into the building structure as an inherent part of the architecture. This article will delve into the differences between BIPV modules and conventional PV modules and analyze their corresponding testing methods.

1. Core Differences Between BIPV Modules and Conventional PV Modules

1.1 Different Functional Positioning and Design Philosophy
Conventional PV modules are primarily designed for power generation, with their design focusing on maximizing solar energy conversion efficiency. They are typically installed on rooftops or the ground via mounting systems and are considered add-on equipment. In contrast, BIPV modules are positioned as a combination of "building material" and "power generation unit," possessing a dual identity. They not only serve as a source of electricity but must also meet various requirements of building materials, such as structural support, thermal insulation, waterproofing, fire safety, and aesthetic harmony. Therefore, the design of BIPV modules requires comprehensive consideration of architectural design and energy needs, making them an organic component of green building implementation.

1.2 Structural and Material Differences
Due to their direct integration into buildings, BIPV modules differ significantly from conventional modules in terms of structure and material selection. Conventional modules typically adopt a standardized laminated structure, including glass, EVA, solar cells, a backsheet, etc., reinforced with an aluminum frame. BIPV modules, on the other hand, may omit traditional backsheets and frames, instead using materials with higher transparency and mechanical strength (such as composite glass or polymer multilayer films). They may even evolve into flexible, colored, or customized forms to adapt to installation needs in different building parts, such as curtain walls, windows, and shading systems.

1.3 Higher Mechanical and Safety Performance Requirements
As part of the building's external envelope, BIPV modules must possess higher mechanical performance and stricter safety standards. In addition to withstanding wind and snow loads like conventional modules, they may also bear structural loads, impact resistance (e.g., hail or falling objects), and even foot traffic. Simultaneously, their fire rating, waterproofing, thermal insulation, and soundproofing performance must comply with building industry standards.

1.4 Complexity of Electrical Safety and Thermal Management Design
BIPV modules are directly embedded into building surfaces, where thermal management conditions may be inferior to the well-ventilated rear installations of conventional modules. This can lead to higher operating temperatures, affecting power generation efficiency and lifespan. Furthermore, due to their proximity to human activity areas, requirements for electrical insulation, arc prevention, and leakage protection are more stringent.

1.5 Aesthetic and Customization Needs
BIPV modules emphasize integration with architectural styles, often requiring customized options in terms of color, transparency, and even shape. Conventional modules, however, generally pursue a higher degree of standardization to reduce costs.

2. Differences in Testing Methods for BIPV Modules and Conventional PV Modules
Given the differences in design objectives and usage scenarios, the testing and certification methods for these two types of modules also vary significantly. Conventional module testing primarily follows international standards such as IEC 61215 and IEC 61730, focusing on performance and reliability. In contrast, BIPV module testing must incorporate building industry evaluation systems in addition to the aforementioned standards.

2.1 Electrical Performance and Reliability Testing
Electrical performance testing is fundamental for both BIPV and conventional modules. This includes power output under standard test conditions (STC), IV curve characteristics, efficiency calculations, etc., using equipment such as solar simulators and IV testers. In terms of reliability testing, both must undergo damp heat, freeze-thaw, thermal cycling, and potential-induced degradation (PID) tests to verify long-term environmental adaptability.

However, for BIPV modules, which may face high-temperature environments, thermal management performance and temperature coefficient testing are particularly important. Additionally, since they may be installed at different tilts or even vertically, their performance under various incident light angles must also be tested.

2.2 Mechanical Performance and Safety Testing
This is the area with the most significant differences in testing methods. Conventional modules primarily undergo mechanical load testing (e.g., 2400 Pa wind/snow load) and hail impact testing. BIPV modules, however, require more extensive mechanical testing, including:

• Structural Strength Testing: Such as bending strength, torsion resistance, and load-bearing capacity testing to simulate their mechanical performance as building materials.

• Impact and Collision Testing: In addition to simulating hail, this may include hard object impact testing to verify resistance to accidental damage when used as walls or roofs.

• Fire Performance Testing: Must strictly comply with building material fire standards (e.g., EN 13501, UL 790) to evaluate combustion ratings, which is a mandatory requirement for building materials.

• Waterproofing and Airtightness Testing: Especially for rooftop or curtain wall BIPV modules, ensuring no leakage during long-term use is critical.

2.3 Environmental Adaptability and Durability Testing
BIPV module testing often includes more items related to actual building environments, such as:

• Enhanced Thermal Cycling and Damp Heat Testing: Due to potentially harsher usage environments, testing conditions may involve extended cycles or increased stress.

• Chemical Corrosion Resistance Testing: Considering potential pollutants in urban air, testing resistance to acid and alkali corrosion is necessary.

• UV Aging Resistance Testing: For transparent BIPV modules, additional evaluation of yellowing, transmittance retention, and encapsulation material degradation under long-term UV exposure is required.

2.4 Building Integration Function Testing
This is unique to BIPV modules and includes:

• Optical Performance Testing: Such as transmittance, haze, and color consistency, particularly for light-transmitting BIPV modules.

• Thermal and Acoustic Insulation Testing: Verifying their thermal and acoustic performance as part of the building envelope.

• Comprehensive Electrical Safety Evaluation: In accordance with building electrical codes, stricter testing of grounding, insulation resistance, and leakage current in BIPV systems is conducted.

3. Conclusion
Although BIPV modules and conventional PV modules share the same power generation principles, fundamental differences in application scenarios and functional positioning lead to significant variations in their design, materials, performance requirements, and testing methods. Conventional modules focus on power generation, with testing emphasizing electrical performance and basic reliability. In contrast, BIPV modules, as an inseparable part of buildings, require a more complex testing system that integrates standards and regulations from both the photovoltaic and building industries.

For manufacturers and testing institutions, it is essential to fully recognize the special requirements of BIPV modules and establish a more comprehensive quality evaluation system. As BIPV technology continues to evolve, corresponding testing standards, methods, and equipment must be continuously improved to ensure their safety, reliability, and efficiency throughout their lifecycle, truly promoting the deep integration of green buildings and renewable energy.