As 2023 begins, all week long, pv magazine takes one last look at 2022 and the key trends it has brought. In the first part of this series, our journalists analyze the increasing adoption of n-type technology by manufacturers, which represents a major step forward in PV cell and module manufacturing in 2022.
The technological development of PV cells and modules has been driven by both power output and cost. While n-type technologies such as heterojunction (HJT) have long demonstrated higher power and conversion efficiencies, less expensive technologies such as p-type cells with passivated emitter-back contact (PERC) have achieved good performance for a much lower cost structure.
In 2022, PERC cells will remain the dominant technology in photovoltaics. Larger wafers combined with half-cells, high-density layout and multiple busbar interconnects, and the use of single-crystal PERC cells have recorded high output powers, enabling the modules to display powers of 400-500W or even more.
However, as PERC cells approached their theoretical efficiency limit of 24.5%, manufacturers turned to Tunnel Oxide Passivated Contact (TOPCon) and HJT cell technology in 2022, based on type # wafers and if successful, the cost structures , particularly with regard to silver consumption for cell metallization, 2022 could well be the year that marks the start of a major technological shift within the industry.
“2022 has been a very exciting year,” said Molly Morgan, senior research analyst at British analyst firm Exawatt. As the efficiency gains of mono PERC modules slowed, we saw many manufacturers adopt n-type technologies, which was reflected in the proportion of n-type modules available in the market; it was fascinating. »
Yield records have been achieved by some manufacturers on n-type technology well before 2022. In August 2021, Chinese cell maker HJT Huasun announced a 25.26% return for a cell in M6 format (166 mm) and thus equals the world record. Greater than 25% efficiency far exceeds what p-type PERCs can achieve, marking a game changer for the industry.
In particular, the production processes that Huasun is currently developing in collaboration with its equipment partner Maxwell differ from the processes previously used by early developers of this technology such as Panasonic and Sanyo.
“Huasun uses microcrystalline and nanocrystalline layers, multiple layers and a two-layer transparent conductive oxide,” explains George Touloupas, chief technology officer at Clean Energy Associates (CEA), a quality assurance provider. Amorphous silicon absorbs a lot of light. For this reason, today the efficiency of the heterojunction is at the same level as that of the TOPCon, despite having a very high voltage, due to the significant problems of light absorption that reduce the current. This is one of the main points that Huasun is currently trying to improve. »
In June, the Chinese monocrystalline ingot and wafer giant Longi broke Huasun’s HJT record with an efficiency of 26.5% on an M6 wafer. While Longi’s first step towards n-type manufacturing appears to be switching to TOPCon for at least some of its PERC production lines, the company may adopt HJT in the near future and is devoting significant R&D resources to this technology.
It should also be noted that HJT’s capacity will be installed outside of China. Resurgent European PV manufacturers, led by Meyer Burger and Enel Green Power, are also continuing their efforts in this technology. Singapore-based manufacturer REC has one of the oldest traditions of HJT production among this second wave of manufacturers with their award-winning Alpha range.
Translation provided by Christelle Taureau.
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