As PERC battery technology approaches its conversion efficiency limit, many companies have turned their attention to more efficient battery technologies, among which TOPCON and heterojunction battery technologies have received the most attention and have the greatest potential for industrialization.
In terms of manufacturing processes, PERC cells require 10 steps: cleaning and texturing, diffusion, laser SE, removal of PSG and back junction, oxidation, front surface SiNx, back surface AlOx/SiNy, screen printing and sintering, photoregeneration, and testing. TOPCON cells have even more, with 12 steps. In contrast, heterojunction cells only require 5 steps: cleaning and texturing, double-sided PECVD a-Si deposition, double-sided PECVD TCO film deposition, double-sided screen printing and sintering, and testing.
In other words, from a manufacturing process perspective, heterojunction solar cells, with fewer steps, should theoretically be cheaper. However, data shows that the current production cost of PERC cells is 0.7-0.75 yuan/W, while the production cost of heterojunction solar cells is 0.9-1 yuan/W, making the latter more expensive.
The main reason for this situation is that heterojunction solar cells require low-temperature silver paste, which is very expensive.
Currently, PERC and BSF cells in the photovoltaic market use high-temperature silver paste, while the low-temperature silver paste required for heterojunction cells is very niche, and naturally, the price is higher.
More importantly, domestic manufacturers have not yet fully mastered the low-temperature silver paste technology. Instead, it is almost "monopolized" by Kyoto ELEX (KE), which has a market share of over 90%, resulting in a slow localization process. This is the fundamental reason for the slow cost reduction of low-temperature silver paste.
Of course, the low level of localization of heterojunction solar cell production equipment also limits the reduction of its cost. The cooperation of the upstream and downstream industrial chains is needed to achieve large-scale mass production of heterojunction solar cells as soon as possible.
