Home > Knowledge > Content
Basic knowledge of photovoltaic
- Apr 13, 2018 -

1. What is photovoltaic power generation? What is distributed photovoltaic power generation?


Photovoltaic power generation refers to the power generation method that uses solar radiation to directly convert electricity into electricity. Photovoltaic power generation is the mainstream of today's solar power generation. Therefore, it is often said that solar power generation is photovoltaic power generation.


Photovoltaic distributed generation is a new type of power generation and comprehensive energy utilization mode with broad development prospects. It advocates the principle of near-infrared power generation, on-site grid connection, near-to-near conversion, and proximity use, and can not only effectively increase the amount of power generated by photovoltaic power plants of the same scale. At the same time, it effectively solved the problem of power loss during boosting and long-distance transportation. However, distributed generation also imposes stringent requirements on how to maximize the amount of solar power generation and how to ensure the safety of the power grid. In this process, the functionality and stability of the photovoltaic inverter also appear to be extremely critical. Distributed generation follows the principles of adapting to local conditions, clean and efficient, decentralized layout, and proximity utilization, making full use of local solar energy resources to replace and reduce fossil energy consumption.


Distributed generation and grid-connected power grids can be used for self-use, extra power online, or they can be purchased and sold in a unified manner (fully sold to the grid).


2. Do you know the historical origin of photovoltaic power generation?


In 1839, when Becquerel, a 19-year-old French physicist, conducted a physical experiment, he discovered that the two metal electrodes in the conductive fluid irradiate with light, and discovered a "photovoltaic effect." In 1930, Former first proposed the use of "photovoltaic effect" to manufacture solar cells and turn solar energy into electrical energy.


In 1932 Odubot and Stora made the first “cadmium sulphide” solar cell.


In 1941 Audu discovered the photovoltaic effect on silicon.


In May 1954, the US Bell Labs Chabin, Fuller, and Peel released the single-crystal silicon solar cell with an efficiency of 6%. This is the world's first practical solar cell, and Wick first discovered arsenic in the same year. Nickel has a photovoltaic effect, and a thin film of nickel sulfide is deposited on the glass to make a solar cell. Practical photovoltaic power generation technology that converts sunlight into electricity is born and developed.


In early 2014, Jinzhai County, our province, to implement the provincial government's new requirements for accurate poverty alleviation, implementation of industrial poverty alleviation "to the village, to the home, to the people, to the industry", in the province took the lead in carrying out photovoltaic power generation poverty alleviation projects.


3. How does a photovoltaic cell generate electricity?


Photovoltaic cell is a kind of semiconductor device with optical and electrical conversion characteristics. It directly converts solar radiation energy into direct current. It is the basic unit of photovoltaic power generation. The unique electrical characteristics of photovoltaic cells are through the incorporation of some of the crystalline silicon. Elements (such as phosphorus or boron, etc.), causing permanent imbalances in the molecular charge of the material, forming semiconductor materials with specific electrical properties, which can generate free charges in semiconductors with special electrical properties under sunlight exposure. Directional movements and accumulations generate electrical energy when they are closed at both ends. This phenomenon is known as the "photovoltaic effect" or photovoltaic effect.


4. What components constitute the photovoltaic power generation system?


Photovoltaic power generation system consists of photovoltaic phalanx (photovoltaic array consists of photovoltaic modules connected in series and in parallel), controllers, battery packs, and DC/AC inverters. The core components of photovoltaic power generation systems are photovoltaic modules, and photovoltaic modules It is made up of photovoltaic cells, connected in parallel and encapsulated. It converts the solar energy directly into electrical energy. The electricity generated by photovoltaic modules is direct current. We can use it to convert it into alternating current and use it from the inverter. From an angle of view, the electricity generated by the photovoltaic system can be used immediately, and it can also be stored with a storage device such as a battery, and can be released at any time for use.


Equipped with accumulators and other energy storage devices will greatly increase the cost of the photovoltaic power generation system. In addition to special applications, it is generally not suitable for promotion.


5. Why PV power is green and low-carbon energy?


Photovoltaic power generation has remarkable energy, environmental protection and economic benefits. It is one of the highest quality green energy. Installation of a 1 kW photovoltaic power generation system under the average sunshine conditions in China can release 1200 kWh power in one year, which can reduce the use of coal (standard coal). About 400 kilograms, reducing CO2 emissions by about 1 ton. According to the results of the World Wide Fund for Nature (WWF) study, the installation of 1 square meter of photovoltaic power generation system is equivalent to 100 square meters of afforestation, and current development of photovoltaic power generation is renewable. Energy is one of the effective means to fundamentally solve environmental problems such as haze and acid rain.


In the mountainous areas of our province, the majority of farmers have always had the habit of burning wood and consume a lot of firewood every year, which has a great impact on the ecological environment. After the implementation of photovoltaic power generation, each household can reduce the consumption of 5,000 kilograms of firewood each year. By developing the photovoltaic industry, farmers can be reduced to payroll. Demand, protect forests, increase forest cover, protect green mountains and green waters.


6. How do you see the news that “the production of photovoltaic modules consumes a lot of energy”?


Photovoltaic cells do consume a certain amount of energy in their production process, especially the energy consumption of industrial silicon purification, high-purity polysilicon production, monocrystalline silicon rods and polycrystalline silicon ingot production, but the photovoltaic cells in 20 years of service life Energy can be continuously generated during the period. It is estimated that under the average sunshine condition in China, the energy return of the photovoltaic power generation system exceeds 15 times of its energy consumption during the whole life span. The energy recovery period for a 1-kilowatt rooftop PV grid-tied system installed in Beijing at an optimal tilt angle is 1.5-2 years, which is far below the lifetime of the PV system. In other words, the amount of electricity emitted in the first 1.5-2 years of the PV system is used to offset the energy consumed in its production and other processes. The energy emitted after 1.5-2 years is pure output. Therefore, the photovoltaic battery should be evaluated from the perspective of the whole life cycle. Energy consumption.


7. How do you view the news that "the production of photovoltaic modules will produce a lot of pollution" news?


Photovoltaic module production includes several industrial chain links including polysilicon, silicon ingot silicon wafers, photovoltaic cells and photovoltaic modules. The related pollution reports mainly refer to the raw materials of photovoltaic modules, the byproducts produced in the production of high-purity polysilicon, and the production of high-purity polysilicon. The main method is to use the modified Siemens method, which converts metallurgical grade silicon into silicon trichlorosilane, which is reduced to hydrogen by solar grade polysilicon. In addition, by-product silicon chloride is formed, and silicon tetrachloride is decomposed into silicic acid in the presence of moist air. With hydrogen chloride, if it is handled improperly, it will cause pollution problems. However, at present, the modified Siemens method adopted by China's polysilicon production enterprises can already achieve closed-loop production, recycling by-product silicon tetrachloride and exhaust gas, and achieve clean production. In December 2010, the State issued the "Polysilicon Industry Access Requirements", which stipulated that the recovery of silicon tetrachloride and chlorine in exhaust gas should be no less than 98.5% and 99%. Therefore, the mature Siemens production technology can fully meet environmental protection requirements. There will be no environmental pollution problems.


8. How much sunlight is available to us? Can it become the dominant energy in the future?


The solar radiation received on the surface of the earth can meet 10,000 times the global energy demand. The average annual radiation received per square meter on the surface of the earth is approximately 1000-2000 KWH depending on the area. The IEA data show that 4% of the world's deserts The installation of solar photovoltaic systems is sufficient to meet global energy needs. Solar PV enjoys a vast space for development and its potential is enormous.


According to preliminary statistics, the market potential of our country to use only existing building-installed photovoltaic power generation is approximately 3 trillion kilowatts or more, plus the potential of the vast Gobi photovoltaic power generation market in the western part is about several billion kilowatts or more, with photovoltaic power generation. With technological advancement and large-scale application, the cost of power generation will be further reduced, and it will become a more competitive energy supply method. It will gradually increase from complementary energy sources to alternative energy sources and hopefully become the dominant energy source in the future.