PERC solar cells
Currently PERC technology is by far the most widespread solar cell structure. At least every second newly installed solar system is equipped with PERC cells. The reason for this is the efficiency: In general PERC solar cells generate around 10% more energy than conventional solar cells even tough the production process differs only slightly and largely uses the same production equipment. This gives cell manufacturers the opportunity to switch very quickly and easily from standard solar cell processing to PERC technology. Solar module assembly also does not deviate from standard technology.
PERC is therefore currently the most cost-effective cell technology with highly efficient energy conversion and maximum energy yield.
What makes a PERC solar cell?
PERC stands for "Passivated Emitter and Rear Contact". Compared to standard solar cells, PERC cells are provided with a dielectric passivation layer on the cell rear side, which usually consists of aluminum oxide (AlOx). This layer plays a significant role for the increase in conversion efficiency:
Reduction of recombination losses
Recombination blocks the free flow of electrons through the cell and thus reduces cell efficiency. Passivation makes the electron flow more uniform and consistent and ensures that more electrical current is generated.
Maximization of light absorption
The rear side passivation layer reflects unabsorbed solar radiation partially back into the solar cell. This again opens the possibility of light absorption and conversion into electrical energy.
Reduction of heat concentration within the cell
Long wavelength light in the range of more than 1,180 nm is not absorbed in the silicon and causes heat generation in the metallization on the back surface. The temperature increase has a negative effect on cell efficiency. This effect can be reduced with backside passivation: the long wavelength light is reflected before it hits the aluminum metallization and exits through the cell. This keeps the PERC solar cell at a lower operating temperature, which has a positive effect on its energy yield.
How does centrotherm process technology contribute?
We provide the thermal key processes such as diffusion and PECVD for the production of PERC solar cells, and are the global technology leader for rear side AlOx passivation.
