Solar PV Technology
The solar PV is the direct conversion of Sun‘s radiation into Direct Current (DC). Solar PV systems shall be designed with either mono/ poly crystalline silicon modules or using thin film photovoltaic cells or any other superior technology having higher efficiency.
Three key elements in a solar cell form the basis of their manufacturing technology.
- First is the semiconductor, which absorbs light and converts it into electron-hole pairs.
- The second is the semiconductor junction, which separates the photo-generated carriers (electrons and holes), and
- The third is the contacts on the front and back of the cell that allow the current to flow to the external circuit.
The two main categories of technology are defined by the choice of the semiconductor: Crystalline Silicon is in wafer form and thin films are composed of other materials.
- Crystalline Technology
Crystalline silicon (c-Si) has been used as the light-absorbing semiconductor in most solar cells, even though it is a relatively poor absorber of light and requires a considerable thickness (several hundred microns) of material.
- Mono crystalline
Produced by slicing wafers (up to 150mm diameter and 350microns thick) from a high-purity single crystal.
- Multi crystalline
silicon is made by sawing a cast block of silicon first into bars andthen wafers. The main trend in crystalline silicon cell manufacture is toward multi crystalline technology.
- Thin film Technology
The materials costs are significantly reduced. The thin film semiconductor layers are deposited on to either coated glass or stainless steel sheet.
- Amorphous silicon
It is the well-developed of the thin film technologies. Disadvantage is such cells suffer from significant degradation in their power output (in the range 15-35%) when exposed to the sun. Better stability requires the use of thinner layers in order to increase the electric field strength across the material. However, this reduces light absorption and hence cell efficiency.