Germany has taken a leading role in the direct generation of electricity from the sun. In terms of sales of newly installed photovoltaic installations Germany took first place in the world in 2007; in regard to production of solar cells it occupies third place with a worldwide share of 20.5 percent. According to a study conducted by the Swiss Bank Sarasin the market for photovoltaic systems, which has increased by 41 percent on average since 2001, will increase further and grow by around 50 percent in the coming years.

Crystalline structures are still dominant. However, the bottleneck in supplies of the raw material silicon has created a boost in investments in thin-layer technology, which uses much less raw material. Currently, the share of second generation solar modules is ten percent, but the European Photovoltaic Industry Association (EPIA) expects to see a rapid increase in this technology in module production to 20 percent by 2010.

In thin-layer technology glass is used as a carrier material and as a cover. The module can be compared to a double-glazed window, explains Siegfried Glaser, Chairman of the glass technology forum in the German Engineering Federation (VDMA), however, instead of gas solar cells are used between the two sheets of glass. The glass technology forum is part of the VDMA portal, photovoltaic production materials, in which all the specialist branches involved with photovoltaics in the VDMA work together.

"The glass industry has adjusted to photovoltaics," says Susanne Schartz-Laux, speaker for the glass technology forum, about the dynamics in the industry, although the special glass is only a "small but important part" in the overall production of glass. This includes, for example, considerable advances in automation. Grenzebach Maschinenbau GmbH, Asbach-Bäumenheim (Germany), offers new systems to mass produce solar cells. It does not matter which type of thin-layer modules are being produced: robots handle the solar modules. Egbert Wenninger, member of the Grenzebach management board, is convinced that this system can reduce the cost per installed watt from the current three to five euros to less than one euro.

Production of thin-layer cells has also taken a leap forward. Lenhardt Maschinenbau GmbH, Neuhausen-Hamberg (Germany), has developed the first solar module in the world that does not have to be laminated. This does away with several minutes processing time in which the very thin films of the solar cells are bonded with the glass sheet.

Flat glass finishing is becoming increasingly important for the glass industry. This also includes the production of glass that is precisely coordinated to the needs of the solar industry. "The production of solar cells is becoming more efficient, faster and less expensive," is how Schartz-Laux summarizes the benefits of the new systems. There are virtually no limits for the new products in terms of shape, size and color. Especially as thin-layer technology is very suitable for countries with predominantly indirect sunlight.

The glass industry reckons that orders for special glass for solar installations will rise considerably. The expert does not expect that there will be a glass shortage: "The right machines and systems are already on the market; this should ensure that the required volumes of glass can be produced."
Robots are used to manufacture thin-layer solar cells.
Photo: Grenzebach.

Robots are invaluable for producing laminate-free thin-layer solar modules.
Photo: Lenhardt Maschinenbau