Solar, Storage

Copper PV metallization yields 18% solar cell efficiency

SCHOTT Solar AG, RENA GmbH, and CiS Forschungsinstitut have created a solar cell with 18% power conversion efficiency manufactured with copper backside metallization.

November 28, 2011 — SCHOTT Solar AG, RENA GmbH, and CiS Forschungsinstitut have created a solar cell with 18% power conversion efficiency manufactured with copper backside metallization.

The partners have been working under the Las VeGaS project for 6 months, aiming to replace the silver contacts used on the front side of solar cells with less-expensive nickel-copper plating. Las VeGaS partners say they can cut photovoltaics manufacturing costs by more than 50% with the copper-based process.

Only a very thin electroplated silver layer is needed to solder the cells to the copper tabs to make a module. This lowers the consumption of silver by at least 95%.

Nickel-copper plating faces the efficiency-reducing challenge of copper diffusion into the silicon solar cell. The team uses an electroplated nickel layer for both a diffusion barrier and as part of the copper contact application. RENA’s InCellPlate technology was used with standard industrial tools for fabrication. The copper-based process meets EU RoHS Directive requirements, avoiding lead and solvents.

This same week, Kaneka and imec announced silver-free heterojunction silicon solar cells fabbed by electroplating a copper grid over the transparent conductive oxide layer. imec measured conversion efficiency at more than 21%.

Las VeGaS’ solar cells will now be used to fabricate test modules to investigate long-term stability.

The team is also developing the technology for use with monocrystalline solar cells, targeting 19%+ efficiency.

The Las VeGaS project that focuses on the long-term stability of front side metallization of solar cells using environmentally friendly electroplated layers, receives funding support from the Federal Ministry of Education and Research as part of the “Innovation Alliance on Photovoltaics.”

SCHOTT Solar manufactures solar wafers, cells and modules. Further information about SCHOTT AG can be found on www.schottsolar.com.

RENA GmbH is one of the largest suppliers of process technology for wet chemical applications, mainly for use in the photovoltaic industry.

CiS Forschungsinstitut für Mikrosensorik und Photovoltaik GmbH is an institution dedicated to application-oriented research and development in the areas of silicon-based sensor technology, microsystems technology and photovoltaics.

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