One way of reducing the cost is to develop cheaper methods of obtaining silicon that is sufficiently pure. Silicon is a very common element, but is normally bound in silica, or. Processing silica (SiO2) to produce silicon is a very high energy process - at current efficiencies, it takes one to two years for a conventional solar cell to generate as much energy as was used to make the silicon it contains. More energy efficient methods of synthesis are not only beneficial to the sola.
The first step in producing silicon suitable for solar cells is the conversion of high-purity silica sand to silicon via the reaction SiO 2 + 2 C → Si + 2 CO, which takes place in a furnace at temperatures above 1900°C, the carbon being supplied usually in the form of coke and the mixture kept rich in SiO 2 to help suppress formation of SiC.
Ultimately, every solar cell begins its life as quartz sand. Also known as silica sand, quartz sand consists of at least 95% pure silicon dioxide, which is also known as silica or as SiO 2. But we don't need silica for solar cells, but silicon, which means we need to get rid of the oxygen, to leave behind pure silicon.
Silica is used to produce metallurgical grade silicon, which then undergoes several stages of purification and refining steps to produce silicon of high purity for applications in the photovoltaic (PV) industry. Apart from its abundance, there are other reasons why silicon remains the material of choice for PV applications.
An essential prerequisite for the growth of crystalline silicon from the raw materials is the availability of silicon of the highest purity attainable. 17 Impurities or defects in the single crystals can lower the performance of the solar cell device due to recombination of charge carriers.
How crystalline silicon is a high efficiency solar cell?
The solar cell efficiency of crystalline silicon is limited by three loss mechanisms: optical losses, carrier losses and electrical losses. The back contact silicon solar cell is another high efficiency device, where all the metallisation on the front surface is removed.
As materials go, pure silicon is remarkably hard. This means you need to get out your (very clean) diamond wire saw to cut the cylindrical crystal of silicon into an ingot with the footprint of a solar cell.