Thin-film silicon tandem (MICROMORPH™) module design and key reliability topics

• Published in: Solar energy materials and solar cells Vol. 152; pp. 170 - 179
• Main Authors: Cervetto, V., Brunner, A., Caglar, O., Cashmore, J.S., Gauckler, J., Hötzel, J.E., Iwahashi, T., Janot, R., Krull, S., Lindic, M.-H., Nishimaniwa, O., Psimoulis, I., Ristau, S., Roth, F., Schoech, H., Schuhmacher, T., Sellner, S., Sinicco, I.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-08-2016
• Subjects: Contact; Contamination; Deposition; Encapsulation; Laser scribe; Lasers; Modules; Photovoltaic; Reliability; Silicon; Solar cells; TCO; Thin films; Thin-film; ZnO; Encapsulation; TCO; Photovoltaic; Thin-film; ZnO; Laser scribe; Reliability; Contamination
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2016.03.029

Thin-film silicon tandem (MICROMORPH™) module design optimization process for performance maximization is described together with an analysis of some key reliability topics.
In the first part, the procedure for module layout optimization to achieve the maximum module power output is described. In monolithic thin-film modules the layout is realized through a laser scribing interconnection process: a well-controlled laser scribing process is therefore essential to ensure optimal module performance and to minimize unwanted losses.
The second part of the paper focuses on some of the materials used in the fabrication of a solar cell and module of such technology and the processes used to achieve such module assembly, as well as a description of some of the possible failure modes. Special attention is paid to the zinc oxide transparent conductive oxide (ZnO TCO) layers used for the front and back contacts.
The bottom cell (BoCe) and its stability is also analyzed in detail: the influence of process parameters on the BoCe degradation behavior including the differences observed using different thin-film silicon (TF-Si) deposition reactor types, different lamination foils and the impact using different front contact haze is discussed.
In the final part of the paper the effect of particle contamination on the module performance is reviewed: specifically contamination by particles generated during deposition and handling processes. Finally relevant countermeasures to prevent additional module performance loss are discussed.
•Optimization of electrical performance by module layout selection and laser process.•Sensitivity of ZnO:B contact layers and stability improvements.•Degradation due to microcrystalline layer quality and particle contamination.