It was the first appearance of the Hi-MO X10 in Europe, but only for insiders, customers and visitors of the ATP Finals in Turin. More than 60 customers were invited to the prestigious tennis tournament, where LONGi is the 2024 solar partner. And it was this mix of tennis and technology that made the meeting in Italy so exciting.
While the Italian player Jannik Sinner won the ATP final for the first time in his career and gave the Italian fans in Turin the home victory they had been hoping for, our local teams were on site spreading the word and providing information about the solar technology of the future: Back Contact Technology, or BC for short. And there is a lot to say and learn about this technology, which has just taken another significant leap forward in terms of efficiency and performance with the launch of the Hi-MO X10.
Back contact technology on the rise in Europe
Overall, it is clear that back contact technology is on the rise in Europe, both in research and industrial applications. It is becoming more widespread and competes with TOPCon, which has also made significant progress in recent years. However, according to leading solar experts and scientists such as Dr Martin Green from the University of New South Wales, it will be back-contact technology rather than TOPCon that will dominate the solar industry in the coming years. By 2023, he is quoted as saying, "I think everyone will eventually be making IBC (interdigitated back contact) cells.
Back contact technology is often considered superior to TOPCon (Tunnel Oxide Passivated Contact) in applications where aesthetics, efficiency and durability are paramount. By moving all electrical contacts to the rear, back-contact cells eliminate front-side shading losses, improve performance, and create a sleek, uniform appearance ideal for residential and high-end installations.
BC cells are also known for achieving a lower levelized cost of energy (LCOE) due to their higher efficiency, improved durability, and reduced operating costs. By eliminating front-side shading losses, they maximize sunlight capture and energy yield, while their superior thermal performance and reduced risk of degradation ensure consistent output over a longer lifetime. Their reliability minimizes maintenance requirements by reducing mechanical stress on the cells. This increases resistance to micro-cracking, which in turn protects the cells. Cells in the Hi-MO X6 family only have to withstand a pressure of 26 MPa, compared to 50 MPa for conventionally welded cells. Considering all these aspects, back contact modules deliver more energy and better financial returns over the lifetime of the system.
The Hi-MO X10 represents the last generation of crystalline silicon cell technology to achieve a 1% leap in absolute efficiency
As the first principle of the PV industry, the development of cell technology and efficiency gains have significantly impacted the PV market over the past 10 years. BC technology has been recognized and endorsed by both academia and industry as the best technology 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.
Since the launch of LONGi's first back-contact module in 2022 with the Hi-MO 6 using HPBC 1.0 (Hybrid Passivated Back Contact Technology), LONGi has invested more than 260 million Euros (2 billion RMB) in R&D and obtained nearly 200 patents to launch the next generation with HPBC 2.0 in 2024. Realized in the new Hi-MO X10 that LONGi showcased during ATP in Turin, there are three innovative breakthroughs for HPBC cells in the areas of cell substrate, passivation technology and process technology. The result is a mass production cell efficiency of 26.6% - a 1% leap over the first generation and a true milestone. This will be the last time that crystalline silicon cell technology achieves a 1% jump in absolute efficiency. The Hi-MO X10 now delivers a module efficiency of 24.8%, resulting in a 5% increase in power per unit area compared to TOPCon. This makes it at least 30W more powerful than a TOPCon module of the same size.
Customers impressed with new n-type TaiRay wafer
The wafer substrate is a major change from HPBC 1.0. LONGi released the TaiRay wafer in March 2024. Not only do they show a 0.1% increase in efficiency per cell, they also have improved mechanical properties. Their tested bending is 16% higher than that of conventional wafers. As a result, they provide higher break resistance with a lower probability of cell breakage during production. In addition, the underlying TaiRay production process reduces the amount of oxygen and other impurities. Single crystal growth defects are all reduced, resulting in improved efficiency. The more impurities that can be removed, the greater the potential for improved cell efficiency.
The bending strength of the TaiRay wafer was of particular interest to the audience, as the wafer substrate itself is an important element in the development and production of a long-term reliable module.
Hi-MO X10 comes with 0BB structure for the first time and an anti-hotspot feature
While back contact is known to have no front grid lines to reduce shading on the module and increase efficiency, the Hi-MO X10 additionally adopts the so-called 0BB structure or zero busbar structure, which results in no back busbars. This new cell design, which has never before been implemented in back contact technology, results in a significant improvement in efficiency and an increase in module power of 5W.
The module incorporates a new shading optimizer that reduces power loss by 70% compared to TOPCon, while using a bypass diode effect to avoid hot spots due to localized overheating when shaded. The overall design used here is called Soft Breakdown Design. This can better ensure the safety and reliability of the product, while bringing high power generation benefits to customers.
The Hi-MO X10 combines all the features demanded by the distributed generation market. High aesthetics, safety and reliability, as well as high performance and low degradation of 1% after the first year.
The Hi-MO X10 sneak preview in Turin will be followed by an official market launch in February in Italy. In the meantime, the France and Belgium market roll out will follow at the beginning of December to be continued with the Nordic countries United Kingdom, Denmark, Norway, Sweden and Finland. The European launch will be phased, with the majority of markets rolling out in the first and second quarters of 2025.
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