Solar cells are the first monocrystalline silicon solar cells. Silicon is a very rich element of the Earth, almost everywhere has the existence of silicon, Solar panel structures can be said to be inexhaustible, with silicon to make solar cells, raw materials are no shortage. But refining it is not easy, so people in the production of monocrystalline silicon solar cells at the same time, also studied polycrystalline silicon solar cells and amorphous solar cells, so far commercial-scale production of solar cells, has not jumped out of silicon series. In fact, there are many semiconductor materials for the manufacture of solar cells, with the development of the material industry, the variety of solar cells will be more and more.
A solar cell is a device that responds to light and converts sunlight into electricity. There are many kinds of materials which can produce photovoltaic effect, Solar panel structures such as: monocrystalline silicon, polysilicon, amorphous si, gallium arsenide, selenium and indium copper, etc. Their power generation principle is basically the same, and now crystalline silicon is an example to describe the process of light generation. P-Type crystalline silicon can get N-type silicon through doped phosphorus, forming N junction.
When the light shines on the surface of the solar cell, some of the photons are absorbed by the silicon material; the energy of the photon is transferred to the silicon atom, which makes the electrons move more and more, becoming the free electrons in the n junction formed the potential difference, Solar panel structures when the external circuit is connected, under the action of the voltage, the current will flow through the external circuit to produce a certain output power. The essence of this process is: the process of converting photon energy into electricity.
A positive charge represents a silicon atom, and a negatively charged four electrons surround the silicon atom. The yellow indicates that the boron atom is doped, because there are only 3 electrons around the boron atom, so the Blue Hole is produced.
When the P-type and N-type semiconductors are combined, a special thin layer is formed in the junction area of the two semiconductors. The electrons in the N region will spread to the P area, and the holes in the P region will spread to n regions, and once the diffusion is formed a "internal electric field" of n pointing to P, thus preventing the diffusion. Until the balance is reached, Solar panel structures a special thin layer forms a potential difference, which is the PN knot.
Since semiconductors are not good conductors of electricity, when electrons flow through a n junction if they are in a semiconductor, a metal mesh is generally used to cover the n knot (such as a comb-shaped electrode) to increase the area of the incident light.
In addition, the silicon surface is very bright, will reflect a large amount of solar light, can not be used by the battery, the scientists gave it a layer of very small reflection coefficient of protective film.
Application prospects of silicon-based solar cells at present, silicon-based batteries have been widely used in industry, agriculture, commerce, Solar panel structures communications, military, aviation and other fields. It also includes household appliances and utilities. The application of silicon-based batteries can be divided into 3 types: grid-connected, Off-grid and home appliances.
Since entering the 21 century, the global grid-connected PV grid-connected generation has increased 44.1 times times. From 2000, the 7MW was increased to 2008 's. 85MW, the average annual growth rate of 60.99%, Solar panel structures year-on-year 2007 growth of 72.65%. The cumulative total of grid-connected photovoltaic grid-connected PV plants grew 10.5 times times, from 2000 1.435G to 2008.4GW, annual growth rate of 35.6%. All over the world the use of solar cells in buildings and home roofs, the radio and television can be connected to the grid.
2. Off-Grid application
Compared with the well network power generation, the power generation has the characteristics of flexibility and so on, and always occupies the market share, such as the power supply for communication relay station and the power consumption in remote mountainous area. In many remote areas such as far away from the city of farms, mountainous areas, vineyards use of the network way to generate electricity, such as water pump power supply system. Power can be up to $number. 3KW.
3. Appliance Application
Although solar power is affected by day and night, rain, and season, it can be dispersed, so it is suitable for decentralized generation of households and connected to the power supply network. Solar cells increasingly become the "energy heart" of household appliances.
(1) Solar telephone. Wireless telephones, powered by solar energy, have been launched in a British radio company. It uses the top-mounted solar receiving board to recharge the battery continuously. The user's voice enters a nearby telephone switch through a radio wave and transmits it to a local telephone network. Solar panel structures The solar-powered public telephone, produced by the Dewarth company in Paris, is extremely low in power consumption, and can be used for more than 10 days if it is recharged in the sun for a few hours.
(2) Solar refrigerator. France's solar refrigerator with methanol for ice-making, every 24 hours can be 10 kilograms of ice, fresh 30 kilograms of food. India has developed a large solar refrigerator for storage, with a parabolic mirror of the upper part concentrating sunlight in the semiconductor mesh hole
, the light into the current, the temperature in the box in-2 Shan, can be refrigerated 500 kilograms of food, a day can also produce 25 kg of ice. (3) Solar air conditioner. Solar panel structures The air conditioner, made by the Japanese Sharp Electric Company, uses a general power supply when the weather is clear, with all the power supplied by the sun, cloudy or cloudy. The period of conversion by the control system automatically completed, with it can make a 18 square meters of room room temperature to maintain in 20 Shan around, Solar panel structures and more than the general air conditioner to save more than 60%.
(4) Solar TV. The solar TV set developed in Finland can watch TV at night without the power supply, as long as the semiconductor silicon light cell converter is placed on a sunny windowsill during the day. The converter stores electrical energy that can be used for 3-4 hours for a TV set with a working voltage of 12 volts. India's solar-powered television, the energy absorption system for only 4 hours a day, Solar panel structures even if there is no sun for 3 consecutive days, can normally receive signal broadcast programs.
(5) Solar camera. Japan produced the world's first solar camera, weighing only 475 grams, equipped with advanced solar cell systems, the battery can be used continuously for 4 years.