New solar cell batteries can generate electricity on both sides of the module

With a simple tip the solar power industry can increase solar power plant productivity by up to 25%: the back of solar panels can also attract sunlight .

People who used to ski know this well: on a Sunday they don't apply sunscreen carefully - then on that evening saw burns on the skin because of sunburn. This is likely to happen because white snow reflects the sun. So the skin must receive a large amount of ultraviolet (UV) rays compared to sitting in the sun on a balcony in the winter.

The photovoltaic industry wants to exploit this effect to increase the productivity of solar power plants. Common solar panels have one drawback: they can only generate electricity on the sun's side, which means that on the front of the battery the sunlight cannot be used.

So research institutes as well as businesses are considering a solar battery capable of turning the solar energy in the back into electricity. Depending on the installation location and its type, it can increase productivity by up to 25% compared to conventional solar panels.

The solar power plant of Ökostrom-Saar.

Large enterprises in the industry such as SolarWorld, Trina Solar, Yingli or LG have launched the first modules of this type to the market. The most obvious difference compared to conventional energy panels is that the back of the panels has a thin glass plate, which is weathered, but still allows the reflected rays to pass through. Types of conventional modules cover a transparent thin film.

The second difference: a metal contact point for conducting electricity - usually made of Aluminum - behind the solar panel, does not cover the entire area as usual."Instead, the contact points [in the new module type] are made of aluminum or silver just like hair fibers, no more than 100 microns thick. Therefore, reflected light rays are easily accessible to the battery no obstacle " , TS. Thorsten Dullweber, at the Hameln Solar Power Research Institute (ISFH) explained.

How much productivity increases depends primarily on the reflectivity on the back of the solar panel and the space at the back of the panels is wide or narrow. If installed on the roof of a dark-colored saddle, these new batteries are not effective. But if installed on a light base or white gravel spread on flat roof, the productivity increases from 10% to 15% compared to conventional panels, according to TS. Dullweber.

For solar power parks in the desert or in other places where the ratio of sand in the ground is high, the effect is as big as the light or white gravel. Mounting solar panels on the price side toward the sun, the level of productivity increases even up to 25%."The reason is mainly because the amount of sunlight that impacts the front of the modules increases. Also behind the modules are more light rays attracted , " Dr Dullweber said.

While the cost of these new solar panels is not too high, it is only 4% to 7% higher than the standard system, compared to increasing productivity from 10% to 15%. It was too good, according to the scientists at ISFH.

In addition, this new plan to use solar panels is also attractive for another reason: the modules here allow electricity to be generated twice a day. A small field experiment conducted by Start Up Next2Sun in Berlin in Saarland, Germany, uses vertical installation in the east-west direction, the front of solar panels produces electricity in the morning, the back provides electricity in the afternoon.

However, compared to wind power plants or other solar power plants, these new solar panels use more area - the range of modules must stand apart to prevent each other. However, this may also be an advantage, according to Heiko Hildebrand, CEO of Next2Sun: Because the range of modules that are far away from each other is in a standing state, the area for these modules is not lost. They can handle ecological functions or serve agricultural production. For example, these solar power parks can dump cattle or plant trees as animal feed.

"For Germany, this option is really appropriate , " said Forscher Kopecek of the ISC Energy Research Center in Konstanz. Next2Sun is currently preparing to continue building these solar power parks. This summer, the Saarland area will have an additional 2 Megawatt solar power plant.