![]() Ancestors of the Pueblo people, called the Anasazi, in North America lived in south-facing cliff dwellings that captured the winter sun.ġ767 Swiss scientist, Horace de Saussure, was credited with building the world’s first solar collector, later used by Sir John Herschel to cook food during his South Africa expedition in the 1830s.ġ876 William Grylls Adams and Richard Evans Day discovered that selenium produces electricity when exposed to light. had large south-facing windows to let in the sun’s warmthġ200s A.D. The famous Roman bathhouses in the first to fourth centuries A.D. A magnifying glass is used to concentrate the sun’s rays to make fire and to burn ants.ġst to 4th Century A.D. Today, we have everything from solar powered buildings to solar-powered vehicles.ħth Century B.C. We started out concentrating the sun’s heat with glass and mirrors to light fires. Its history spans from the 7th Century B.C. Solar energy is captured in a variety of ways, the most common of which is with photovoltaic solar panels that convert the sun’s rays into usable electricity. If you connect the n-type and p-type layers with a metallic wire, the electrons will travel from the n-type layer to the p-type layer by crossing the depletion zone and then go through the external wire back of the n-type layer, creating a flow of electricity.Solar power is usable energy generated from the sun in the form of electric or thermal energy. ![]() If this happens in the electric field, the field will move electrons to the n-type layer and holes to the p-type layer. When sunlight strikes a solar cell, electrons in the silicon are ejected, which results in the formation of “holes”-the vacancies left behind by the escaping electrons. The presence of these oppositely charged ions creates an internal electric field that prevents electrons in the n-type layer to fill holes in the p-type layer. When all the holes are filled with electrons in the depletion zone, the p-type side of the depletion zone (where holes were initially present) now contains negatively charged ions, and the n-type side of the depletion zone (where electrons were present) now contains positively charged ions. This creates an area around the junction, called the depletion zone, in which the electrons fill the holes (Fig. Near the junction of the two layers, the electrons on one side of the junction (n-type layer) move into the holes on the other side of the junction (p-type layer). ![]() In the n-type layer, there is an excess of electrons, and in the p-type layer, there is an excess of positively charged holes (which are vacancies due to the lack of valence electrons). Instead, it is free to move inside the silicon structure.Ī solar cell consists of a layer of p-type silicon placed next to a layer of n-type silicon (Fig. It bonds with its silicon neighbor atoms, but one electron is not involved in bonding. Phosphorus has five electrons in its outer energy level, not four. The n-type silicon is made by including atoms that have one more electron in their outer level than does silicon, such as phosphorus. ![]() Because boron has one less electron than is required to form the bonds with the surrounding silicon atoms, an electron vacancy or “hole” is created. The p-type silicon is produced by adding atoms-such as boron or gallium-that have one less electron in their outer energy level than does silicon. A solar cell is made of two types of semiconductors, called p-type and n-type silicon. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |