Shingled Cell Interconnection: A New Generation of Bifacial PV-Modules

12 Pages Posted: 29 Mar 2018 Last revised: 20 Apr 2018

See all articles by Nils Klasen

Nils Klasen

Fraunhofer Institute for Solar Energy Systems (ISE)

Andrew Mondon

Fraunhofer Institute for Solar Energy Systems (ISE)

Achim Kraft

Fraunhofer Institute for Solar Energy Systems (ISE)

Ulrich Eitner

Fraunhofer Institute for Solar Energy Systems (ISE)

Date Written: April 15, 2018

Abstract

The idea to interconnect solar cells in a shingled manner like roof tiles dates back to the 1960’s. However, the standard interconnection technology in the PV industry nowadays is still the front to back series interconnection using solder coated copper ribbons. Shingle interconnection offers very high packing densities of solar cells and increases the module’s active area by eliminating busbars from the illuminated area. Direct interconnection of stripe-like solar cells by electrical conductive adhesives (ECA) replaces the front-to-back ribbon interconnection and therefore eliminates the interconnectors’ ohmic losses. Stripe-like solar cells additionally reduce the overall ohmic losses of the solar cell string by lower cell currents.

In this work we provide an overview of the scientific state of the art and a summary of the most important features for shingled cell interconnection. We compare two calculation approaches for the joint deformation due to thermal expansion of the module materials and identify the most relevant parameters. The results show that the thickness of the joint material typically ranging from ~ 20-100 µm is crucial to reduce the shear deformation and therefore enabling sufficient long-term stability. Other geometrical parameters like the overlap width or number of solar cells per string only show a small effect on shear strain for cell widths >20 mm. First experimental prototypes of shingled mini-modules of bifacial pSPEER solar cells using low temperature soldering (Sn42Bi58) show a total power loss of < 5 % after accelerated TC200 testing.

Keywords: Shingling, Bifacial Solar Modules, pSPEER

Suggested Citation

Klasen, Nils and Mondon, Andrew and Kraft, Achim and Eitner, Ulrich, Shingled Cell Interconnection: A New Generation of Bifacial PV-Modules (April 15, 2018). 7th Workshop on Metallization and Interconnection for Crystalline Silicon Solar Cells, 2017, Available at SSRN: https://ssrn.com/abstract=3152478 or http://dx.doi.org/10.2139/ssrn.3152478

Nils Klasen (Contact Author)

Fraunhofer Institute for Solar Energy Systems (ISE) ( email )

Heidenhofstrasse 2
Freiburg, DE 79110
Germany

Andrew Mondon

Fraunhofer Institute for Solar Energy Systems (ISE) ( email )

Heidenhofstrasse 2
Freiburg, DE 79110
Germany

Achim Kraft

Fraunhofer Institute for Solar Energy Systems (ISE) ( email )

Heidenhofstrasse 2
Freiburg, DE 79110
Germany

Ulrich Eitner

Fraunhofer Institute for Solar Energy Systems (ISE) ( email )

Heidenhofstrasse 2
Freiburg, DE 79110
Germany

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