Why LONGi believes that back contact technology is the future of solar technology

As the first principle of the PV industry, the development of cell technology and efficiency achievements have significantly influenced the PV market in the past 10 years. BC technology has been recognized and endorsed by both academics and scientists, such as Dr. Martin Green, and the industry as the best technological path for the near and mid-term future. It is the last generation of silicon-based cell technology for PV modules, and the advantages and benefits it brings are unmatched in the market.

Back contact modules are known for their higher performance, increased reliability, especially in harsh environments, attractive aesthetics, and high returns. With the increasing challenges in the world, including harsh climates and hot regions, back contact technology is the technology that can withstand and handle this in a viable way.

In 2023, LONGi Chairman Zhong Baoshen emphasized that he believed BC technologies offered greater scope for continuous efficiency improvement than other technologies. He saw unlimited potential. He added that BC products would also set new standards in terms of aesthetics and could be integrated into various application scenarios, especially the already thriving distributed photovoltaic market. They offer outstanding adaptability, and with increasing market demand for both aesthetics and long-term performance and reliability, especially in challenging climates, their market success is unquestionable, he said in an opinion piece in European trade media.

In December 2024, he highlighted LONGi’s commitment to advancing solar back contact technology again and emphasized its impact on the European market while affirming LONGi’s commitment to supporting Europe’s energy transition.

Back contact technology allows for a high level of light absorption

Back contact cells feature a unique design with no front busbar. This significantly improves light absorption as there is no shading caused by the busbar. It also has a positive effect on the photoelectric conversion capacity compared to conventional technologies such as TOPCon. More light can be converted into power. This is especially true in low light conditions. The module ensures maximum energy output even in low light conditions. To give a concrete example, LONGi's Hybrid Passivated Back Contact Technology modules get up early in the morning and go to bed late at night, delivering excellent performance parameters. This proves once again that the maximum wattage figure advertised for modules does not necessarily reflect the reality of daily performance.

Combined with additional features such as improved temperature coefficient and low degradation, this results in excellent energy and economic gains.

Back contact technology modules have a higher reliability and long-term stability

LONGi back contact modules use a back-contact soldering technology that deploys a single-line solder structure instead of the traditional Z-shaped structure. This cell contacting results in lower mechanical stress on the cells and increases the resistance to microcracks and thus also the protection of the cells since the cell edge stress is almost halved. The cell edges in LONGi’s HPBC cells only must withstand a pressure of 26 MPa, while cells with conventional welding are subjected to a pressure of 50 MPa.  

To prove this, we tested the modules to exceed the IEC standard values. Strict material selection, controlled manufacturing, and demanding stress tests (hail, hurricane, high temperature, dynamic load, etc.) during the production process ensure high reliability and product quality.

With the introduction of HPBC 2.0 as the second generation of its Hybrid Passivated Back Contact technology, LONGi has reached the pinnacle of crystalline silicon having achieved a 1 percent jump in absolute efficiency from the first to the second generation.

For future efficiency enhancements, we also believe that back contact technology has more potential than TOPCon.