Technological change path of TOPcon, HJT, IB three kinds of photovoltaic cells
Jun 02, 2022
The main concern of the photovoltaic industry is to reduce the cost of electricity per kilowatt hour. Therefore, the direction of change in battery technology revolves around the determinant factor of cost reduction and efficiency increase. In the past two years, the mass production efficiency of PERC has approached the limit, which has led to various companies attaching great importance to the research and development of next-generation technologies. At present, the main technology paths in the market are TOPcon (PERC + transformation), HJT (heterojunction), IBC (Interdigitated Back Contact Solar Cell).
Comparing the principles of the three technical routes, from illumination to current transmission, optical loss and electrical loss will occur in the middle, thereby reducing the conversion efficiency. Therefore, in order to reduce electrical losses, HJT uses intrinsic amorphous silicon + doped amorphous silicon for electron and hole selection, and TOPcon uses silicon dioxide + doped polysilicon for electron and hole selection. In order to reduce the optical loss, the IBC adopts structures such as adding an antireflection layer and trapping light to form a back-contact battery.
Comparing the above three technical routes, the conversion efficiencies produced by different technical routes are different.
The average efficiency of the current TOPcon production line is 23.5%~24.5%, and the laboratory efficiency is 26% (the domestic Zhonglai conversion efficiency is the highest at 25.4%). The main reason why TOPcon is put into production faster than HJT and IBC is that the production line can be transformed on the PERC line, which brings less investment.
The mass production efficiency of the HJT production line is 24%, mainly because there are not many production lines on a large scale at present, and the highest conversion efficiency in the laboratory is 26.30% of LONGi. The advantages of HJT are short process flow (4 links) and high conversion efficiency. However, due to the current high cost (the investment of a single GW equipment is 400-450 million yuan), it has not yet been industrialized on a large scale (but the cost reduction path is clear: equipment cost reduction, silver paste cost reduction, target material and silicon wafer cost reduction ). Figure HJT capacity planning.
The BC process is compatible with HJT equipment and processes, and the mass production conversion efficiency is 25%~26.5%. In the latest research, the efficiency of PSC-IBC cells combined with IBC and perovskite has exceeded 30%, and the efficiency of PSG-IBC tandem cells has exceeded 35%. %. However, due to the complex and expensive production process of IBC batteries, only a few companies have production lines (Aixu has 6.5GW and 2GW in Zhuhai and Yiwu respectively, and LONGi has 4GW in Taizhou).
In general, the short-term TOPcon industry chain is the most mature and leading in mass production. At this stage, HJT has difficulties in mass production and high investment costs. In the medium term, it is expected that the three routes will coexist, and the mainstream in the future will be IBC batteries (TBC or HBC) with higher efficiency and lower silver consumption. From the perspective of technological change, investment ideas should be grasped: one is to grasp the major changes in photovoltaic cell technology, and leading technology companies have the advantage of increasing market share + technology premium. The second is the rapid release of performance in related technical supporting links (low-temperature silver paste, targets, etc.)
