BC achieved the highest absolute efficiency gain of 1.6 percentage points from January 2023 to June 2025, extending its band from 22.8% to 24.4%
AIKO set successive records, raising its commercial BC module efficiency first to 24.2% in May 2024 and then to 24.4% in June 2025
LONGi improved its HPBC efficiency to 24.2% in June 2025, Maxeon stayed at 24.1% since 2024, while SPIC remained stable at 22.8% since 2023
In the TaiyangNews TOP SOLAR MODULES Analysis H1-2025, we looked at the share of different cell technologies in the high-efficiency module segment. After covering technology shares in previous articles, we now turn to efficiency developments, tracking how each technology has advanced over time. The focus here is on Back Contact (BC) technology.
BC has achieved the highest absolute efficiency improvement over the past 2.5 years, with a gain of 1.6 percentage points between January 2023 and June 2025. The same 1.6% delta also applies when comparing the lowest and highest points within June 2025. In H1 2025, the lower limit of the BC efficiency band remained unchanged at 22.8%, while the upper limit was extended further by AIKO, which increased the top efficiency of its commercial BC module to 24.4% in June 2025. This 0.2% absolute gain over its previous 24.2% record from May 2024 strengthens BC’s leadership in high-efficiency performance – making it the first and only cell technology to reach this mark with commercially available modules.
In 2024, the efficiency band for BC remained consistent from January to April, with a lower limit of 22.8% and an upper limit of 24%. In May, AIKO raised the upper limit to 24.2%, setting a new benchmark for BC efficiency. This record efficiency remained unchanged for the rest of the year, solidifying BC's position as a leader in module efficiency.
In 2023, BC’s efficiency range saw some significant developments. In March, the upper limit increased to 23.6% and further improved to 24% by June. From September onwards, the lower limit also improved from 22.3% to 22.8%, narrowing the efficiency range. This 22.8% to 24% range remained steady through the end of the year and into early 2024.
Moving on to the companies and their respective efficiencies, the most notable advancement in H12025 came in June when AIKO increased the top efficiency of its commercial BC module from 24.2% to a new benchmark of 24.4%, further extending its lead in the efficiency race. In the same month, LONGi raised the efficiency of its HPBC module to 24.2%, improving from 24.1% in March 2025, and reclaiming exclusive hold over the 2nd rank in the TOP SOLAR MODULES list. Before this, in March, LONGi had already raised its product efficiency from 23.2% to 24.1%, matching Maxeon’s level. Throughout this period, SPIC continued to list its BC product at 22.8%, unchanged since September 2023 (see TOP SOLAR MODULES Listing – June 2025).
In 2024, 2 major developments reshaped the BC landscape in May. AIKO continued its legacy with the commercialization of its Comet 2U series, achieving a record-breaking 24.2% efficiency, reaffirming its lead among BC products. AIKO improved the efficiency from an already high base of 24%. Simultaneously, Maxeon Solar, a pioneer in back-contact technology, commercialized a 24.1% efficiency module, taking the 2nd position in the TOP SOLAR MODULES listing. These advancements remained untouched for the rest of the year, as did the remaining BC product portfolio with LONGi at 23.2% and SPIC at 22.8%.
The most prominent development in BC in 2023 was AIKO’s debut in our TOP SOLAR MODULES listing. The company made headlines in March with a module series surpassing 23% efficiency, actually reaching 23.6% efficiency. The very next month, in April, LONGi improved the efficiency of its HPBC commercial modules to 23.2% from the 22.8% level it shared with Maxeon. This propelled LONGi to the 2nd-highest position in both the BC and the entire TOP SOLAR MODULES list. AIKO once again shocked the industry when it broke its own record in June by introducing a 24% efficiency commercial module based on the BC architecture in June 2023. In August, Maxeon improved its efficiency from 22.8% to 23%. Then, SPIC upgraded its BC technology in September to base it on TOPCon, realizing an absolute efficiency gain of 0.5% by attaining 22.8% efficiency, improving from the 22.3% level. The status quo was maintained through the end of the year.
This text is an edited excerpt from the TaiyangNews TOP SOLAR MODULES H1-2025 report, which can be downloaded for free here.
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