Solaranlage mit Sonne

Economic efficiency

As the economical efficiency is depending of various items, we are spotting on the panel itself here.




Effieciency of solar cells



Today’s commercial solar cells, most often made from silicon, typically convert sunlight into electricity with an efficiency of only 10 percent to 20 percent. Given their manufacturing costs, modules of today’s cells incorporated in the power grid would produce electricity at a cost roughly 3 to 6 times higher than current prices.
Current standard cells have a theoretical maximum efficiency of 31 percent because of the electronic properties of the silicon material. New materials, arranged in a new way, can evade that limit, with some multilayer cells reaching 34 percent efficiency.
Experimental cells have exceeded 40 percent efficiency.
Another idea for enhancing efficiency involves developments in nanotechnology, the engineering of structures on sizes comparable to those of atoms and molecules, measured in nanometers.
Recent experiments brought up intriguing advances in the use of nanocrystals made from the elements lead and selenium. In standard cells, the impact of a particle of light (a photon) releases an electron to carry electric charge, but it also produces useless excess heat. Lead-selenium nanocrystals enhance the chance of releasing a second electron rather than the heat, boosting the electric current output.
Other experiments state this phenomenon could occur in silicon as well. Theoretically the nanocrystal approach could reach efficiencies of 60 percent or higher. Engineering advances will be required to find ways of integrating these nanocrystal cells into a system that can transmit the energy into a circuit.

New materials for solar cells help reduce fabrication costs


A key issue is material purity. Current solar cell designs require high-purity, and therefore expensive materials, because impurities block the flow of electric charge. This problem would be reduced if charges had to travel only a short distance, through a thin layer of material. But thin layers do not absorb as much sunlight to begin with.
A possibility to solve this problem would be to use materials thick in one dimension, for absorbing sunlight, and thin in another direction, so that charges could travel. One such strategy envisions cells made with tiny cylinders, or nanorods. Light could be absorbed down the length of the rods, while charges could travel across the rods’ narrow width. Another approach involves a combination of dye molecules to absorb sunlight with titanium dioxide molecules to collect electric charges. But to make such systems competitive a large improvement in efficiency will be needed.