The sun is a fantastic source of renewable energy, and the technologies to capture this energy are ever improving. Perhaps the most well-known of these technologies is the solar panel, which transforms light energy into electric potential energy. But how does a solar panel work? This article that I’ve written explains the workings of the solar cell, the small discrete components that make up solar panels. Enjoy the read!
The solar cell converts electromagnetic radiation energy into electrical energy. It utilizes the photovoltaic effect to create electron-hole pairs, which, under the influence of the electric field created by the diode of the cell, moves apart to the opposite ends of the diode. This movement leads to a current when the ends of the diode are connected to an external circuit. The photovoltaic effect occurs when a photon of sufficient energy is absorbed by a valence electron in an atom, and the electron gains the necessary energy to become unrestrained from the atom and move freely in the material. This effect leads to the creation of a pair of charge carriers: the electron and the positive ion from which the electron left. The ion is viewed as a hole – a position that is missing an electron. In order to harness the energy of these electron-hole pairs, they need to move in opposite directions to an external circuit. This is where the diode becomes crucial. Solar cell consists of two distinct semiconducting silicon plates. These plates are doped with small amounts of foreign elements: one contains elements such as phosphorus, antimony, or arsenic so that for each of these foreign atoms, there is an extra electron that is not used to bind with adjacent silicon atoms in the crystal lattice; the other contains elements such as boron, aluminum, and gallium so that for each of these foreign atoms, there is the lack of an electron required to bind with adjacent silicon atoms. These are called the negative and positive type materials, respectively, which is abbreviated to n-type and p-type. When these two plates are put in contact, a diode is formed. In the contact region of a diode, some of the electrons from the n-type moves to the holes in the p-type. Thus, the n-type becomes positively charged, while the p-type becomes negatively charged. This creates an electric field from the n-type to the p-type, and any free electrons in this region will move to the n-type, while any holes will move to the p-type. When an electron-hole pair is created by an incident photon through the photovoltaic effect, the electron and the hole will move to the opposite ends of the diode, as described above. Thus, when the ends of the diode are connected to an external circuit, the electron will move through the external circuit before returning to the other end of the diode, instead of simply crossing over to the other side of the diode. The hole moves oppositely to the electron, although at this point, both simply describe the current. When enough photons of sufficient energy are hitting the solar cell, a significant current would be generated. The direction of the conventional current is from the p-type to the n-type. This is the solar cell's process of electricity generation.
Comentarios