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Lossen J.,International Solar Energy Research Center Konstanz | Matusovsky M.,Utilight Ltd. | Noy A.,Utilight Ltd. | Maier C.,CiS Research Institute for Micro Sensors and Photovoltaics | Bahr M.,CiS Research Institute for Micro Sensors and Photovoltaics
Energy Procedia | Year: 2015

Pattern Transfer Printing (PTPTM) is a patented novel non-contact printing technology developed and commercialized by Utilight for advanced front side metallization of c-Si PV solar cells. As PTPTM is based on laser induced deposition from a polymer substrate, the geometry of the printed features is not restricted by the characteristics of a printing screen, allowing for much finer, higher and uniform fingers. We present the results achieved by printing the front side finger lines and bus bars of mono- and multi-crystalline solar cells with PTPTM technology and compare these with results of neighboring cells manufactured by state-of-the-art screen printing technology. Finger lines with high aspect ratio and uniform line shape down to 20 μm width could be printed. Solar cells with 29 μm wide double printed PTP finger lines show an efficiency increase of up to 0.4%abs. © 2015 The Authors.


Yusufoglu U.A.,RWTH Aachen | Lee T.H.,RWTH Aachen | Pletzer T.M.,RWTH Aachen | Halm A.,International Solar Energy Research Center Konstanz | And 4 more authors.
Energy Procedia | Year: 2014

Bifacial solar modules are becoming increasingly more attractive stimulated by the development of new solar cell structures enabling to capture solar insolation on both front and rear surfaces. The possibilities to be installed in the conventional south facing orientation or even vertically are further advantages. Although the potential of bifacial modules have been already shown in specific time intervals and for various ground albedos there is a lack in simulation studies up to now. In this study, we simulated the annual energy yield (AEY) of south facing bifacial modules using a rigorous calculation method of the ground reflected radiation reaching the rear module surface. The necessary tilt angle optimization is done incorporating the influence of module elevation and considering the inherent albedo coefficient. These simulations are able to reproduce measurement observations and show that at optimum tilt angles produced annual energy can be increased by 30% compared to a standard module simply by positioning modules two meters above ground instead of a close to ground installation. Furthermore, a linear relationship between albedo coefficient and AEY is demonstrated. © 2014 The Authors. Published by Elsevier Ltd.


Koduvelikulathu L.J.,International Solar Energy Research Center Konstanz E.V | Mihailetchi V.D.,International Solar Energy Research Center Konstanz E.V | Comparotto C.,International Solar Energy Research Center Konstanz E.V | Buck T.,International Solar Energy Research Center Konstanz E.V | Kopecek R.,International Solar Energy Research Center Konstanz E.V
Energy Procedia | Year: 2014

In this study we investigate, using a two dimensional simulation tool, the characteristics of the metal-Si emitter interface of screen printed and firing through contacts. In the model we assumed that the metal contact to n+ or p+ emitters is either Ohmic or Schottky and the dominant current conduction mechanism flow is directly through Ag-crystallite. The simulation results were then compared with the experimental data for the contact resistance (ρc) and fill factor (FF) of p-type cells with an n+ phosphorous diffused emitter and n-type cells with a p+ boron diffused emitter. The emitters of p-type and n-type cells were metalized using an Ag paste or, in case of p+ doped emitters, by an AgAl paste. From the modeling of Si-emitters contacted by a screen printed Ag paste, a Schottky contact, assuming literature value for Ag work function, agrees with the experimental IV data for n+ emitters, but does not agree for the p+ emitters. Assuming only a Schottky contact at metal-p+ emitter interface, the model fails to estimate simultaneously VOC and FF of the cells contacted by an Ag paste. Thus, the current transport mechanism at Agp+ emitter interface may not be dominated by direct metal-Si contact through Ag-crystallites imprints but, possibly, by tunneling through a thin interface glass layer that resulted ( in this case) in high contact resistance as observed experimentally. Therefore modeling Ag-p+ emitter interface using an Ohmic contact with a high contact resistance agrees better with the experimental IV data. © 2014 The Authors. Published by Elsevier Ltd.


Patent
International Solar Energy Research Center Konstanz E.V. | Date: 2016-12-14

The invention provides a method for doping of silicon wafers (8) using a diffusion oven (1), said diffusion oven (1) having a door (2) for loading and unloading of the silicon wafers (8), an inner volume (6), gas inlets (4) for a reaction gas, a doping gas and a carrier gas and means for modifying the flow rate of said reaction gas, said doping gas and said carrier gas into the interior volume (6) of the diffusion oven (1), said method comprising the steps of loading silicon wafers (8) into the diffusion oven (1), heating the diffusion oven (1) in accordance with a predetermined temperature profile at least during a deposition time, letting reaction gas, doping gas and carrier gas flow simultaneously into the inner volume (6) and unloading the doped silicon wafers (8) from the diffusion oven (1), wherein during the deposition time in which reaction gas, doping gas and carrier gas flow simultaneously into the interior volume (6) of the diffusion oven (1), the ratio of the flow rate of reaction gas and flow rate of doping gas is changed at least once from a first ratio to a second ratio and/or the flow rate of the carrier gas is changed at least once from a first flow rate to a second flow rate.


Patent
INTERNATIONAL SOLAR ENERGY RESEARCH CENTER KONSTANZ e.V. | Date: 2014-05-28

The invention relates to a method for producing a solar cell composed of crystalline silicon, as well as a solar cell of said type. The substrate of said solar cell has, in a first surface, a first doping region produced by boron diffusion and, in a second surface, a phosphorus-doped second doping region.

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