Technologies for using regenerative energy sources are considered a real market of the future. Generation of solar energy is currently very popular. But the effectiveness and the manufacturing costs of industrial solar cells are currently far from optimum. Laser technologies should now provide for increases in efficiency and reductions in costs...

The trend in manufacturing solar cells is currently going in the direction of thinner and larger silicon wafers. Too many wafers break during production using traditional screening methods. But the reject rate can be reduced using lasers - even when working thinner or larger silicon wafers - because it works contact-free. In addition, the degree of automation can be increased further using laser technologies and consequently production costs can be reduced.

Among others, the Laser Center Hanover (LZH) and the Institute for Solar Energy Research (ISFH), Hameln/Emmerthal are working on corresponding concepts. The goal of the joint research project is also to create new solar cell concepts with a high degree of efficiency suitable for industrial use as well as optimum utilization of the cell surface.

In this way, for example, the contacts can be placed on the back using tiny laser drillings and the available surface increased by approximately 6 percent. Or the surface is structured like a pyramid using laser processing, which increases absorption of sunrays and consequently the efficiency of solar cells.

The increase of solar cell efficiency and consequently cost-cutting in solar cell production across the complete value-added chain is also a goal of the "SolarFocus" project, in which 12 companies of the German photovoltaics industry and 12 research partners have teamed up.

The focus of the project, which is subsidized by the German Ministry of the Environment with 4.1 million euros, is the silicon material used in solar cell production. Among other things, the currently used silicon material is being investigated in a "defect analysis" here, for example, with large-area imaging measurement techniques such as electroluminescence (EL) and LightBeam - InducedCurrent (LBIC) in combination with local investigations into material segments using transmission electron microscopy (TEM). This makes it possible to identify and analyze areas with poor material quality and consequently develop new strategies for crystallizing and processing silicon.

You can find additional information about the projects at www.laser-zentrum-hannover.de and www.solarfocus.org.