Even though heterojunction (HJT) solar cell technology is known to generate higher module efficiencies, its high cost vis-à-vis TOPCon gives the latter an edge when it comes to replacing PERC. Nonetheless, work is ongoing to reduce HJT costs with reduced use of silver, finger width and wafer thickness. Now, HJT cell manufacturers count the use of phototransfer film as contributing to improving its power generation capacity and lower costs.
HJT cells typically cannot make use of the ultraviolet (UV)-portion of the light, which is mainly due to the losses incurred by the absorption of this portion of light by TCO and doped silicon thin film layers. The mean UV band of the incident light does not actively contribute to charge carriers' generation. The phototransfer film overcomes this issue.
As the name suggests, phototransfer film, commercialized by Cybrid Technologies in 2022, converts UV rays into visible light and actively contributes to photovoltaic generation in HJT cells, thereby enhancing power output by 1.5% to 2% or 10 to 12 W per module. An indirect benefit of technology is that it simply avoids UV portion of the light reaching the PV device, thereby reducing the UV-induced degradation of HJT modules, a root cause for accelerated aging mechanism of HJT. To put it simply, the phototransfer film, in addition to improving the performance of the HJT modules, also helps in expanding the life of a HJT module by reducing its degradation. The film technology is adapted on to the encapsulation materials and the beauty of the approach is that it can be applied on to any encapsulation material platform.
TÜV Rheinland conducted tests to determine the impact of phototransfer films on HJT module performance in October 2022. It took measurements within an irradiance range of 100-1100W/m² and a temperature range of 15-75° Celsius and determined an increase of 1.22% in the power output of HJT modules as against those using conventional cut-off film.
According to leading HJT solar cell manufacturers like Akcome, these films push up a module's power output as well, by as much as 10 W.
According to Cybrid's collection of thoughts from various industry experts, the HJT module shipments would reach 10 GW in 2023 and grow 5-folds to 50 GW by 2024. As for capacities, Cybrid's phototransfer film customer Huasun Energy forecasts global HJT module production capacity to increase to between 150 GW and 200 GW by 2025. Cybrid calculates that roughly estimated at 1,200 effective sunlight hours/watt, phototransfer film is predicted to bring an additional power generation of 1.476 billion kWh to 1.968 billion kWh annually. It explains that this amount is comparable to the annual power generation of the world's largest hydro-solar hybrid power station on Yalong River.
Citing research in the field of HJT cell technology, Cybrid believes there is scope for future cost reduction of phototransfer films through increased localization and yield improvement. "This anticipated decrease in cost holds significant appeal for HJT manufacturers, making the adoption of this technology highly attractive," it added.
With increasing demand from other manufacturers as well, like Risen Energy and WINHITECH, Cybrid expects to ship around 5 GW of phototransfer films annually.
Earlier in November 2023, Cybrid announced plans to set up a 50 GW solar film + PV cell packaging material facility in Xuancheng, China (see China Solar PV News Snippets).
Cybrid will be part of TaiyangNews Virtual Conference on High Efficiencies Solar Technologies-Today, Tomorrow and Beyond where on December 14, 2023 it will talk about the company's breakthrough encapsulation solution to mitigate the UV-absorption losses for HJT cells. The virtual conference is scheduled to be held on December 13 and 14 with a focus on TOPCon and HJT, and on December 19 and 20 to discuss TOPCon and XBC and next generation technologies, respectively. Registrations to the event are free and can be done here.
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