|Basic structure of silicon based solar cell|
Photovoltaics is the field of technology and research related to the practical application of photovoltaic cells in producing electricity from light, it is often used specifically to the generation of electricity from sunlight.
The solar cell works in three steps:
- Photons in sunlight hit the solar panel and are absorbed by semiconducting materials, such as silicon.
- Electrons (negatively charged) are knocked loose from their atoms, causing an electric potential difference. Current starts flowing through the material to cancel the potential and this electricity is captured.
- Due to the special composition of solar cells, the electrons are only allowed to move in a single direction.
The efficiency of a solar cell may be broken down into reflectance efficiency, thermodynamic efficiency, charge carrier separation efficiency and conductive efficiency. The overall efficiency is the product of each of these individual efficiencies.
Silicon based solar cell
This diagram shows a typical crystalline silicon solar cell. The electrical current generated in the semiconductor is extracted by contacts to the front and rear of the cell.
The top contact structure which must allow light to pass through is made in the form of widely-spaced thin metal strips it is also called as fingers that supply current to a larger bus bar.
The cell is covered with a thin layer of dielectric material - the anti-reflection coating, ARC - to minimise light reflection from the top surface.