2023-12-13 ニューサウスウェールズ大学(UNSW)
◆UNSWは、これらの故障モードに対処するための高速試験法を開発し、信頼性向上が持続可能で経済的なエネルギーのソリューションに寄与し、再生可能エネルギーテクノロジーへの信頼を維持するのに重要であると述べています。
＜関連情報＞
- https://newsroom.unsw.edu.au/news/science-tech/sun-derperfoming-why-new-wave-solar-panels-may-lose-their-spark-too-soon
- https://www.sciencedirect.com/science/article/pii/S0927024823004257?via%3Dihub
- https://www.sciencedirect.com/science/article/pii/S0927024823003756?via%3Dihub
ナノスケールバリア層の適用によるSHJ電池のナトリウムイオン関連劣化への対処 Addressing sodium ion-related degradation in SHJ cells by the application of nano-scale barrier layers
Xinyuan Wu, Chandany Sen, Haoran Wang, Xutao Wang, Yutong Wu, Muhammad Umair Khan, Lizhong Mao, Fangdan Jiang, Tao Xu, Guangchun Zhang, Bram Hoex
Solar Energy Materials and Solar Cells Available online: 20 October 2023
DOI:https://doi.org/10.1016/j.solmat.2023.112604
Highlights
•NaCl reduces SHJ solar cell performance by ∼30% after 20 h of damp heat testing.
•Both the front and rear cell sides of SHJ cells degrade due to an increasing series resistance (Rs) and recombination.
•AlOx capping layer effectively safeguards SHJ cell performance by reducing NaCl-induced losses to only ∼3.3%rel.
•Ultra-thin AlOx layer reduces Rs and recombination losses, and protects SHJ cells from Na ions.
•AlOx deposition is compatible with existing industrial tools, providing a practical solution for SHJ cell preservation.
Abstract
Silicon heterojunction (SHJ) solar cells are renowned for their high efficiency. However, SHJ solar cells are susceptible to various contaminants, leading to significant performance degradation when exposed to damp-heat conditions (e.g., 85 °C and 85% relative humidity). Sodium (Na) has been identified as one of the main contributors to degradation in silicon solar modules subjected to damp-heat conditions. This work investigates the role of an ultra-thin AlOx capping layer (∼10 nm) in preventing the failure in SHJ cells caused by Na-related contaminants. NaCl is applied directly to the solar cell, and the unencapsulated cell undergoes a damp heat test at 85 °C and 85% relative humidity (DH85). It is found that without the AlOx barrier layer, the SHJ cells experience a relative reduction in power of ∼30%rel after only 20 h at DH85. Both the front and rear sides of the cell degrade when exposed to NaCl. This is primarily due to a deterioration of the Ag contact resulting in increased series resistance (Rs), and decrease in fill factor (FF), and an increase in recombination, leading to a significant drop in open-circuit voltage (Voc), particularly when NaCl is applied on the rear side. However, when an AlOx barrier layer is applied to the SHJ cells, the performance losses caused by NaCl are significantly reduced to only ∼3.3%rel. The loss in Voc on the rear side is completely suppressed, and there is only a slight increase in Rs of ∼50%rel compared to ∼300%rel increase in Rs for cells without the AlOx barrier layer. These findings indicate that the ultra-thin AlOx barrier layer provides effective protection for SHJ cells against Na ions, mitigating both Rs and recombination losses. This AlOx barrier layer depositing method is compatible with existing industrial mass-production ALD tools and thus presents a viable solution at the cell level for SHJ cells.
塩化ナトリウムを用いた二面シリコンHJT、PERC、TOPCon太陽電池のセルレベルでの促進耐湿熱試験 Accelerated damp-heat testing at the cell-level of bifacial silicon HJT, PERC and TOPCon solar cells using sodium chloride
Chandany Sen, Xinyuan Wu, Haoran Wang, Muhammad Umair Khan, Lizhong Mao, Fangdan Jiang, Tao Xu, Guangchun Zhang, Catherine Chan, Bram Hoex
Solar Energy Materials and Solar Cells Available online :12 September 2023
DOI:https://doi.org/10.1016/j.solmat.2023.112554
Highlights
•TOPCon cells degrade the most (Pmax loss of ∼75%rel), followed by HJT cells (Pmax drops ∼50%rel) and PERC (Pmax drops ∼10%rel).
•The front of the PERC and the TOPCon solar cell’s rear are stable.
•These degradation effects can primarily be attributed to the increased series resistance (Rs) observed on the front side of TOPCon cells, both sides of HJT cells, and the rear side of PERC cells.
•Rs rises due to metal contact corrosion caused by Na+ and Cl– ions penetration.
Abstract
Bifacial passivated emitter and rear cells (PERC) currently have the highest share in the photovoltaic market. However, heterojunction (HJT) and tunnel oxide passivated contact (TOPCon) solar cells are expected to gain significant market share shortly. Despite technological advancements, concerns about the reliability of HJT and TOPCon technologies when deployed in the field still need to be addressed. This work investigates the impact of sodium chloride (NaCl) on damp-heat-induced degradation in bifacial HJT, PERC, and TOPCon solar cells by exposing the solar cells to NaCl before damp heat (DH) testing. It is found that among all investigated cell technologies, TOPCon solar cells degrade the most with maximum power (Pmax) loss of up to ∼75%rel, followed by HJT (Pmax drops ∼50%rel), and PERC cells (Pmax drops only ∼10%rel) after 20 h of DH testing, mainly attributed to an increase in Rs on the front side of TOPCon cells, both sides of HJT cells and the rear side of PERC cells. The front of the PERC and the rear of the TOPCon solar cell are found to be stable. The rise in Rs is attributed to the corrosion of the metal contact, which is caused by a high amount of Na+ and Cl− ions penetrating the metal contact. This corrosion leads to increased porosity, detachment of the contact from the silicon interface, and increased recombination loss in some cases. These results are crucial for all cell technologies as they highlight the potential failures that could occur in the field. Na+ and/or Cl− ions are common contaminants present in solar glass, human fingerprints, soldering flux, rainwater, soil/dust, and seawater. During field operation, these ions have the potential to penetrate and directly interact with solar cells. In our view, the preferred solution is for the solar cells to be corrosion-resistant, which can be rapidly assessed using the method presented in this work.
