Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Bottom-to-top process: Thick film metallisation

ECN applied improved processing for texturing, emitter formation and BSF on material from three batches of TOPSICLE material. The best efficiency obtained is 16.7%. This cell has a single layer SiNx:H coating. With an additional MgF2 coating the efficiency could be improved with about 0.5% absolute.

Bottom-to-top approach using screen printing ECN optimized the process on Topsicle material (mainly Topsicle I material) in phases:
- Optimizing texturing and emitter formation
Texturing using in-line acidic etching was adjusted for the Topsicle I material. After texturing an emitter of 80 Ohm/sq emitter was applied. Firing optimization and using a single layer SiNx:H ARC resulted in a best cell efficiency of 16.7%. After applying an additional MgF2 layer the efficiency should increase with about 0.5%. On other material (commercially available) an independently confirmed efficiency of 17.0% was reached.

- Improved BSF formation
The optimized BSF process found in WP2 was applied on Topsicle I material. The efficiency gain using the improved BSF formation was about 0.2%. The improved BSF formation is used to obtain 17.0%. With an additional MgF2 coating the efficiency could be improved with about 0.5% absolute. The 17.0% process was applied on a larger amount mc-Si wafers and the average efficieny obtained was 16.8%. A first full size module made of these cells has an encapsulated cell efficiency of 16.8% corresponding to a power of 94.3 Wp.

The knowledge developed on this topic, will on one hand be assessed by the industrial partner SCHOTT Solar, and on the other hand contribute to the basic knowledge of the researchers.

SCHOTT Solar GmbH is a direct end-user and will exploit the results of the project. One important step achieved within the project was the development of a high-efficiency mc Si solar cell process sequence based on isotexturing and screen-printing together with the consortium partner ECN. Comprehensive assessment at SCHOTT Solar and common experiments with ECN and UKON within the project revealed that both, enhancement of efficiency and decrease of depreciation and consumables cost, help to reduce the solar cell production cost per Wp significantly. The isotexturing cell process adaptation to industrial boundary conditions was already started at SCHOTT Solar during the project and is now under development. Approval for introduction into solar cell production is expected with the next year.

The researchers will exploit the public knowledge through publications and conferences, and the specific knowledge through their knowledge position.

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