BIPV solutions offer multiple advantages compared to traditional BAPV systems
LONGi offers 2 types of BIPV products - LONGi BRIGHT (colored aesthetic BIPV) and LONGi ROOF 4 (C&I roof BIPV)
With multiple additional features, the LONGi ROOF 4 series BIPV product can outperform traditional rooftop systems
Not only $/Wp, conventional building-integrated photovoltaic (BIPV) modules are primarily driven by values associated with $/aesthetics, $/robustness, kg/Wp, and others. To replace equivalent building materials, these modules need to possess both electrical and building material properties. However, elevating the usage of BIPV modules in conventional commercial & industrial (C&I) roof spaces calls for additional features to overcome the limitations of traditional rooftop PV systems.
In this context, Song Zhang, CTO of LONGi’s BIPV Business Division, gave an insightful presentation at the TaiyangNews Advanced Solar Module Applications 2024 Conference (see LONGi's presentation here). He introduced LONGi’s innovative BIPV product lines: LONGi BRIGHT (colored BIPV) and LONGi ROOF 4 (C&I rooftop BIPV).
Opening with a comparative analysis between BIPV and BAPV, or Building Applied Photovoltaics, Zhang highlighted the advantages of the former. The 'A' in BAPV stands for 'Applied,' meaning the modules need to be attached to the building envelope using a rack-mounted system. In contrast, the 'I' in BIPV stands for 'Integrated,' indicating that these modules replace certain building materials, such as the roof or facades. While installing a BAPV system destroys the building envelope and disrupts the intended look of the building, BIPV provides additional building protection coupled with enhanced aesthetics, added Zhang. However, safety risk due to a lack of standardization of BIPV technology, inconsistent appearance with the building's design concept, and contradiction between excess PV capacity and insufficient consumption load are some of the challenges being faced by BIPV projects.
According to Zhang, the real value of a BIPV system can be realized by addressing a few theoretical areas, such as research on the production system, particularly understanding the boundaries of 2 precision works - the building integrated PV industry and traditional construction materials.
Next, he briefed about the Green Building System – the importance of humanity integration in line with regional cultures and inheritance, introducing a more intelligent and digital function system to improve the quality and safety of the system, and offering comprehensive solutions for different functions of the building.
The LONGi BRIGHT series is a BIPV product that can be integrated into any opaque and flat area of the building, including roofs, facades, sunshades, and guardrails. This highly aesthetic PV product, designed in line with building material properties and comparable, or even a replacement, to traditional building materials, has reliable power generation properties, says Zhang.
It is offered in up to 5 standard colors, aligning with regular building material colors, such as blue for glass, red for brick ,and gray, white, or beige for metal. The reliability of these colors, on the back side of the tempered glass, is guaranteed for the whole lifecycle based on advanced inorganic coloring technology. This module features a 7-layer structure design from airside to rear side – colored tempered glass-LONGi patented adhesive film-monocrystalline PV cell-adhesive film-black backing plate-adhesive film-tempered glass. Zhang further noted that the patented adhesive film makes the module resistant to high temperature, impact, and sticks to the glass fragments and prevents them from falling due to glass breakage.
Aligning with the structural modulus of conventional buildings, LONGi BRIGHT comes in 3 different sizes – Large (2,085 x 1,185 mm), Medium (1,185 x 1,185 mm), and Small (1,185 x 585 mm). In terms of rated power, their output power per m2 differs according to their size and color, added Zhang.
LONGi BRIGHT has passed the building material test, including a Class A fire protection level, electrical safety test to ensure 100% insulation, and also dustproof and waterproof properties. Additionally, it also went through enhanced environmental stress tests like the static mechanical load test of up to 5,400 Pa, TC200, HF10, PID192, UV60 test, and more. On top of the 5-year product warranty and up to 25 years of power warranty, LONGi BRIGHT provides a color warranty of up to 10 years, says Zhang.
Addressing some safety risks of BAPV applications due to its installation method, environmental factors, and mismatched lifespan between buildings and PV modules, LONGi developed the LONGi ROOF 4 series. This BIPV product, equipped with 144 HPBC half-cut cells, boasts a power output of up to 620 W and an efficiency of up to 23.13%. This non-divisible metal roof system consists of 2 parts – HPBC PV module and a patented structural adhesive connected with the PV module and a steel plate. Zhang further described that the steel plate has a crest in the middle, leaving space for junction boxes and cables, while the 3 layers below are the regular functional layers of the building’s metal roofing system. In terms of the product size, this LONGi ROOF 4 series, featuring a 2 mm + 2 mm double glass structure, comes in dimensions of 2,368 x 1,128 x 5 mm.
Regarding the aesthetic quotient, its front busbarless design makes it easier to integrate into the existing building appearance. In terms of safety and reliability, this product has passed a strict wind resistance test that can withstand typhoons above level 17. Zhang says that thanks to the patented structural adhesive, which is UV-resistant and highly stable, the product provides reliable bonding with PV modules with an over 25-year lifespan. He further pointed out that this product is water-leakage free due to its unique structural design and is Class A system fire certified.