Modules: Back-contact to the Future
By George Touloupas, Amy Fang, and Molly Morgan
This article was originally published in pv magazine - December 2024 Edition.
Three technology streams emerged as highly ranked entrants for the modules award in 2024: heterojunction (HJT), tunnel oxide passivated contact (TOPCon), and back-contact (BC) devices. This year’s winner reflects the direction of things to come. In 2024, BC solar has surged into the spotlight with a winner not only worthy of recognition on the basis of performance, but also for its role in pushing BC into the mainstream.
Winner
Aiko Solar Energy, Infinite Module Series
Photo: Aiko Solar Energy
Aiko is not the first manufacturer to embrace BC tech, but the third generation of its All Back Contact (ABC) module series is setting new standards for high performance. It boasts module efficiency of 25%, which translates to a 20 W to 30 W increase in output. That takes its rooftop module to outputs of between 655 W and 680 W and its utility-scale device beyond 700 Wp.
“In terms of module design, Aiko has made great efforts to increase the light-receiving area of ABC Infinite modules,” the Chinese manufacturer said in its award application. That statement neatly encapsulates the technique.
By relocating metallization and cell interconnection to the rear of the cell, an unobstructed module frontside greets the sun’s rays, increasing the “power generation area,” said Aiko. Along with the back-contact technique, Aiko has also deployed zero-busbar (0BB) interconnection tiling cell placement, which Aiko has described as “linear” stack welding.
“These innovative designs have enabled the Infinite module to achieve a larger light-receiving area and higher efficiency, and further enhanced the aesthetic value based on the fully black design,” said Aiko.
On top of boosting efficiency, Aiko’s ABC approach enhances power output due to the Infinite modules’ resistance to partial shading. It boasts a good temperature coefficient and a resistance to microcracking. Aiko’s Infinite module series was unveiled in June 2024, and will enter mass production at the end of this year.
Jury comments
Amy Fang: Aiko’s Infinite Module series utilizes n-type ABC cells plus 0BB technology, overlap welding and hidden busbars. These innovative designs have improved conversion efficiency. The series offers solutions for various market segments.
Molly Morgan: Aiko’s Infinite series is a very good back-contact candidate to pick up the 2024 award. The module is leading the market in terms of maximum efficiency and Aiko’s module offerings have led our analysis for over a year. Despite the technology’s smaller market impact, because of its smaller market share in comparison to TOPCon, Aiko does deserve credit for putting out such a good module and helping to drive the technology category forward.
George Touloupas: The fact that Aiko is not using silver is very significant – silver consumption is a big problem for PV. They are also using tiling, overlapping the cells, to help to deliver these incredible module efficiencies. There is a ton of innovation happening in this module. Hopefully the availability of these modules will be good and at an attractive cost.
Highly commended
Astronergy, Astro N7 series
Photo: Astronergy
BC solar may represent tomorrow but n-type TOPCon is today – and the Astronergy Astro N7 series serves as one of the best examples of the technology. Astronergy claims to be one of the first mainstream manufacturers to bring n-type TOPCon to the market and, with 23.3% module efficiency and 630 W power output in a rooftop format, it is clearly delivering high performance.
Alongside power output, Astronergy highlights durability in its Astro N7 series. The Chinese producer reports that it deploys “laser-induced firing” (LIF) technology, which is an advanced metallization technique that facilitates the use of “low-corrosion paste” in manufacturing. Additionally, the company’s use of “upgraded” 2.5 mm by 2.5 mm glass on both sides of the product delivers enhanced hail resistance.
Astronergy reports that the N7 has bifaciality of 80% – a bonus in large scale applications and a potential advantage over BC modules. TOPCon modules are everywhere in 2024 but the Astro N7 series manages to stand out from the crowd.
Jury comments
George Touloupas: The Astronergy Astro N7 series really does point to the latest cell and module improvements with TOPCon technology, including the introduction of laser-assisted firing to address corrosion concerns that was a challenge for TOPCon. It is a combination of all the small changes that are creating very promising pathways for TOPCon.
Molly Morgan: It is nice to acknowledge Astronergy’s N7 series entry – particularly given that TOPCon dominates the market share at the moment, alongside its leading cost-per-watt.
Amy Fang is an InfoLink senior analyst who focuses on the solar cell and module segment of the PV supply chain, working across price trend forecasting and production data.
Molly Morgan is a research analyst at Exawatt, which is a CRU company. Her areas of focus include tracking and forecasting evolution in solar module efficiency and architecture. She analyzes PV production, capacity, and financial data.
George Touloupas is the Senior Director of Technology and Quality for solar and storage at Clean Energy Associates. Since 2010, Touloupas has been active in technical consulting for PV manufacturing, project development, and solar and energy storage projects.
