solar cell process is always only a part of sunlight to electricity which strikes them. The rest goes through the cells or is reflected directly from the surface. Against the reflective coating has been devised which is a standard in production long ago. And the light that passes through the cells? This can be exploited when they can generate electricity even on their back. Bifazial or both sides to call such cells and the resulting manufactured modules, explains Stephan Hotz by the machine manufacturer Singulus Technologies AG.
“That is, in a bifacial module is about the reflection of solar energy from a light background or a light entered ground on the back of the light in the cell and thereby achieves a much better utilization of the energy of solar radiation and a higher module performance. “
Singulus has machines developed that every manufacturer of solar cells and modules made of crystalline silicon can convert its production to the new technology. The efficiency of solar cells is increasing by one to two percentage points. The main reason is that bifacial cells require very high quality silicon, as it needs the semiconductor industry.
More Power “harvest”
The additional costs will be outweighed by the higher power. By using the light on the back of a solar module can also bifaziales achieve higher energy yields. How much higher – it depends on whether the cell is equally refined on the back as on the front. More importantly, what material is the back of the module. SolarWorld AG showed the trade fair Intersolar Europe bifaziales a module with a back glass. Only in this way the potential could be fully realized, says development manager Holger Neuhaus. How much more power can be harvested on the same area, the company is testing yet.
“We have built several test fields, both in Germany and in the US. We believe that for normal installations it so will be about ten to 15 percent more. If you have very optimal conditions that can be sometimes 20 percent. “
Optimum conditions mean that the modules are mounted on a light floor or a bright facade , The darker the surface, the weaker the effect of the power-generating back. Rainer Ruschke holds the two side modules just for roof systems for rewarding. He had produced his Algatec GmbH five years ago first brands. At that time, the market for it is not but have been ripe, he says.
“I need a relatively small area to enhance the performance of the solar module. The performance improvement I can achieve those by developing highly efficient cells, but which also cost more money and that’s a way to generate more power at least square meters today. “
Two-sided modules just for roof systems suitable
The fact that now is also a good demand for bifacial modules there, witnessed LG Electronics. Two years ago, the South Korean company introduced two other power-generating modules and builds up the production capacity of today. One distinguishes LG from the other producers: Back closes a white film, the module explains the Head of Sales for Germany, Bastian Roesch:
“We catch the light in the cell interstices in which then almost on the white back sheet is reflected and thus reaches the bottom of the cell. In the module composite captured light so we can thus exploit better. “
The current production let so increase by two to three percent. Bifacial modules are in the industry now apparently in the world’s most widely used silicon technology to make a breakthrough. Because the change in the production succeeds relatively simple and involves a significant added value for the user, says Holger Neuhaus of SolarWorld. Fueled by spreading plant engineers from Germany and Switzerland, who presented their concepts for the Intersolar. The company Singulus recorded so far ten customers worldwide, says Stephan Hotz.
“The Bifazial cell concept is in development until six months ago, nine months and is now installed at the first customer. This means that first systems have been installed. I would say it is still at the stage of pilot production. The customers are now looking how to increase efficiency and cost optimization takes place and then go into mass production and there convert their other systems. This is the moment the trend . “