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Berlin, Germany

Hamann L.,University of Stuttgart | Benstetter G.,Deggendorf University of Applied Sciences | Hofer A.,Deggendorf University of Applied Sciences | Mattheis J.,Solsol GmbH | And 2 more authors.
IEEE Journal of Photovoltaics | Year: 2015

Reducing the amount of silver is one of the most important ways to reduce the cost of photovoltaic cells. The common way to reduce silver consumption on a cell is the reduction of the metal content in the paste. We present a new paste with silver-coated nickel particles, reducing the silver amount and still keeping the properties of silver related to oxidation and sintering. This paper shows the limits in conductivity due to porosity and oxidation of coated-metal particle pastes in comparison with silver pastes. Simulations and cell tests show that coated-metal particle pastes reduce silver consumption without decreasing the cell efficiency replacing busbar pastes. Coated-metal particle pastes are able to decrease silver consumption for rear-side busbars to cAg < 1.4 mg/cm2, leading to a conductivity σBB = 1.1105 S/cm, without decreasing cell or module efficiency. The conductivity of coated-metal particle pastes is too low using pastes with coated-metal particles as a replacement for the metallization paste for grid fingers but good enough to replace the silver paste for busbars with a cheap alternative. © 2015 IEEE. Source


Hamann L.,University of Stuttgart | Haas M.,Solsol GmbH | Wille W.,Solsol GmbH | Mattheis J.,Solsol GmbH | Zapf-Gottwick R.,University of Stuttgart
Energy Procedia | Year: 2013

With decreasing module prices on the spot market, the cost of silver is getting more and more important in solar cell fabrication. Silver is necessary for the front side metallization and the rear side bus bar metallization in a solar cell. The front side benefits from the good conductivity of silver whereas the rear side bus bars need the low oxidation degree and thus the good solderability of this noble metal. We replace silver bus bars by a metal paste containing a combination of different metals with a silver content below 40%. Thus we reach a silver reduction of 30% compared to conventional rear bus bar metal paste. Multi crystalline silicon solar cells with the new paste achieve identical efficiencies compared to cells with silver reference pastes, tested on 150 cells per batch. The new paste simply replaces conventional rear bus bar metal pastes and passes the common tests. Reliability tests are in progress at the moment. As a pretest, cells with the paste passed a hot-water test. Losses in efficiency of the cells due to corrosion are comparable to the losses of cells with reference silver paste. © 2013 The Authors. Source

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