Stable passivation of cut edges in encapsulated n-type silicon solar cells using Nafion polymer

Stable passivation of cut edges in encapsulated n-type silicon solar cells using Nafion polymer

Chen, N. (TU Delft Photovoltaic Materials and Devices; International Solar Energy Research Center (ISC))
Tune, Daniel (International Solar Energy Research Center (ISC))
Buchholz, Florian (International Solar Energy Research Center (ISC))
Roescu, Razvan (International Solar Energy Research Center (ISC))
Zeman, M. (TU Delft Electrical Sustainable Energy)
Isabella, O. (TU Delft Photovoltaic Materials and Devices)
Mihailetchi, Valentin D. (International Solar Energy Research Center (ISC))

Electrical Sustainable Energy

2023

In this study, the edge passivation effectiveness and long-term stability of Nafion polymer in n-type interdigitated back contact (IBC) solar cells are investigated. For new module technologies such as half-cut, triple-cut, or shingled modules, cutting of the cells introduces unpassivated edges with a high recombination rate and this limits the module power. These cut edges can be “repassivated” after cutting and in this work Nafion polymer is used to achieve this. First, different edge types, namely emitter edges (n+/n/p+) and back surface field (BSF) edges (n+/n/n+), as well as different cutting techniques such as laser cut and cleave (L&C), thermal laser separation (TLS), and mechanical cleaving are evaluated. It is found that TLS and mechanical cleaving enable good repassivation on both BSF and emitter edges. Second, industrial-size IBC solar cells are made to assess the effect of the edge repassivation on performance. On 1/4-cut M2 size IBC cells with two emitter edges, efficiency is improved by over 0.3%abs. However, an efficiency improvement was not observed for similar cells with BSF edges, due to an insufficient passivation at the bulk edges. Last, the real-world stability of the Nafion repassivation is evaluated in industrially relevant module stacks by laminating the repassivated wafers with ethylvinylacetate (EVA) or polyolefin elastomer (POE) encapsulants and then exposing them to industry standard testing of 1000 h under damp heat conditions (85 °C, 85% relative humidity). The tests reveal that the repassivation is stable in EVA encapsulants but not in POE.

Edge passivation
Laser cut
Cut loss
Silicon solar cell
Back contact
Nafion

http://resolver.tudelft.nl/uuid:a5b4a4c2-c438-43d6-aa77-0e2be9aea1b6

https://doi.org/10.1016/j.solmat.2023.112401

2023-12-12

0927-0248

Solar Energy Materials & Solar Cells, 258

Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Institutional Repository

journal article

© 2023 N. Chen, Daniel Tune, Florian Buchholz, Razvan Roescu, M. Zeman, O. Isabella, Valentin D. Mihailetchi