The Hi-MO5 High-Power Bifacial Module for Large Solar Parks

Expert Interview – Monday, August 09, 2021

Interview with Dr. Hongbin Fang, Director of Product Marketing, LONGi Solar Technology Co., Ltd. - Intersolar AWARD Winner 2021 about LONGi’s Hi-MO5 high-power bifacial module for large solar parks.

You have been nominated for the Intersolar AWARD 2021 with your product Hi-MO5. Briefly describe your innovation.

Dr. Hongbin Fang, Director of Product Marketing, LONGi Solar Technology Co., Ltd.

The Hi-MO5 is a bifacial module with ultra-high output for large PV power plants. The module's front output is up to 545 watts and its efficiency is 21.3 per cent. Hi-MO5 uses the latest developments and innovations at wafer, cell and module level.

Starting at the wafer level, the Hi-MO5 is built with 182 mm wafer format. We developed the wafer and module size with different aspects in mind: Production costs, module reliability, system compatibility, transport and the ease of manual installation. Taking transport as an example, the container size for the M10 wafer is fully considered. Hi-MO5 is the optimal size for global transport and takes into account that transport resources are scarce and high transport costs need to be optimised.

LONGi's R&D team has improved the gallium (Ga)-doped M10 standard silicon wafers (182 mm) to produce a P-type mono PERC module with the lowest LID (light induced degradation). To improve the efficiency of the module, we innovatively applied 'Smart Soldering' in Hi-MO5. This proprietary technology uses integrated segmented solder ribbons.

The triangular section of the ribbon maximises solar energy capture, while the flat section enables micro-gap cell interconnection (cell spacing is reduced to 0.6 mm compared to traditional 2 mm cell spacing). As a result, the efficiency of the module is 0.3 per cent higher than that of the traditional module. The "Smart Soldering" technology delivers higher module efficiency with better light capture and smaller cell spacing. It also improves the reliability of the module through crack-free cell connections. Hi-MO5 is packaged as a bifacial module with "double glass + frame". This design can ensure that the module has a high mechanical load capacity.

Who is the product suitable for? What is the target group and what is the target market?

Hi-MO5 modules are suitable for large power plants worldwide. That is where their advantages are most evident. The size of the module is optimised for worldwide transport and its weight for handling by two people in a large power plant. Its power is fully compatible with the central and series inverter for the large-scale power plant on the ground.

What was the trigger for your innovation? What problem does your innovation solve?

Conventional module design is based on device compatibility or experience from semiconductor technology. But photovoltaics is different from the semiconductor industry. Also, the chaos of standards for silicon wafers and modules has driven up costs throughout the photovoltaic industry chain due to production line changeovers and inventory problems. The introduction of the 182mm wafer will reunify the wafer standard, reduce the waste of resources as well as promote the development of the photovoltaic industry.

Boron-oxygen-induced light-induced degradation (B-O linked LID) has affected the performance of photovoltaic modules. But gallium-doped positively charged wafer technology (P-type wafer) without boron-oxygen, which has lower light-induced degradation (LID), is more difficult and expensive. LONGi has effectively addressed this problem with advances in technology and mass production, achieved comparable costs that gallium-doped and boron-doped silicon wafers produce, and enabled a module with lower degradation. Another phenomenon is that the efficiency of the cell in mass production is 23 per cent, but the efficiency of the module is below 21 per cent. There is a big difference between the efficiency of the cell and the module. That's why we developed the smart soldering technology to fully utilise the light, reduce the cell gap and narrow the efficiency gap.

How does your innovation fit with industry trends in Europe / worldwide?

The high efficiency and performance of the Hi-MO5 module reduces the BoS (Balance of System) costs of the power plant. In combination with the reduction of manufacturing and transport costs by the Hi-MO5 module, the LCOE of photovoltaic power plants can be significantly reduced.
By using a 182 mm wafer, the investment, energy and material consumption per watt of Hi-MO5 is reduced. The manufacturing process of Hi-MO5 is cleaner due to its low carbon footprint, which supports the realisation of carbon neutralisation in addition to PV electricity.
Currently, Jinko, JA, LONGi and other manufacturers of Tiler 1 type modules have reached a consensus on the standard of M10 wafers. The M10 standard wafer and module will be more conducive to power plant design and maintenance.

What will be the next step in development?

LONGi continues to promote the standardisation of M10 wafers and modules in the industry. The approach of using larger wafers and modules to increase power per module and thus improve BoS savings reaches its optimum with the M10-72 cell format. Further increasing module power with larger dimensions has limited potential to further reduce BOS costs, while reliability risks jump. Our next focus will be on improving cell and module efficiency so that the industry can return to the race to improve module efficiency instead of increasing module size. The Hi-MO N module released within SNEC - PV POWER EXPO uses LONGi's newly developed HPC technology. And the module efficiency can reach up to 22 percent.

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