Photovoltaic Basic Knowledge Collation

1.

What is photovoltaic power generation? What is distributed photovoltaic power generation?

Photovoltaic power generation refers to the power generation method that directly converts solar radiation into electrical energy. Photovoltaic power generation is the mainstream of solar power generation today. Therefore, what people often say about solar power generation is photovoltaic power generation.

Distributed power generation refers to photovoltaic power generation facilities built near the user's site. The operation mode is mainly for self-use on the user side, and the excess power is connected to the grid, but the balance adjustment of the power distribution system is characteristic of photovoltaic power generation facilities.

Distributed power generation follows the original test of adapting measures to local conditions, clean and efficient, decentralized layout, and nearby utilization, making full use of local solar energy resources, and replacing and reducing fossil energy consumption.

 

2.

Do you know the historical origin of photovoltaic power generation?

In 1839, when 19-year-old French Becquerel was doing physical experiments, he found that the current of two metal electrodes in the conductive liquid would be strengthened when they were irradiated with light, thus discovering the "photovoltaic effect". In 1930, Lange proposed for the first time to use the "photovoltaic effect" to manufacture solar cells, turning solar energy into electricity.

In 1932 Odubot and Stola made the first "cadmium sulfide" solar cell.

In 1941 Audou discovered the photovoltaic effect on silicon.

In May 1954, Chapin, Fuller, and Pearson of Bell Laboratories in the United States developed a monocrystalline silicon solar cell with an efficiency of 6%, which was the first solar cell with practical value in the world. In the same year, Wick first discovered arsenic Nickel has a photovoltaic effect, and a nickel sulfide film is deposited on the glass to make a solar cell. The practical photovoltaic power generation technology that converts sunlight into electrical energy was born and developed.

 

3.

How do photovoltaic cells generate electricity?

A photovoltaic cell is a semiconductor device with light and electricity conversion characteristics. It directly converts solar radiation energy into direct current. It is the most basic unit of photovoltaic power generation. The unique electrical characteristics of photovoltaic cells are obtained by doping certain Elements (such as phosphorus or boron, etc.), thus causing a permanent imbalance in the molecular charge of the material, forming a semiconductor material with special electrical properties, free charges can be generated in semiconductors with special electrical properties under sunlight, these free charges Orientation moves and accumulates, so that electric energy is generated when its two ends are closed. This phenomenon is called the "photovoltaic effect" or the photovoltaic effect for short.

 

4.

What components does the photovoltaic power generation system consist of?

A photovoltaic power generation system consists of a photovoltaic square array (a photovoltaic square array is composed of photovoltaic modules connected in series and parallel), a controller, a battery pack, a DC/AC inverter, and other parts. The core component of a photovoltaic power generation system is a photovoltaic module, and the photovoltaic module is made of photovoltaic cells connected in series, parallel, and packaged. It converts the light energy of the sun directly into electric energy. The electricity generated by photovoltaic modules is a direct current. We can use it or use an inverter to convert it into an alternating current for use. From a perspective, the electric energy generated by the photovoltaic system can be used immediately, or it can be stored in energy storage devices such as batteries, and released for use at any time as needed.

 

5.

What is a distribution network? What is the relationship between the distribution network and distributed photovoltaic power generation?

The distribution network is a power network that receives electric energy from the transmission network or regional power plants and distributes it locally through power distribution facilities or to various users step by step according to voltage. It is composed of overhead lines, cables, towers, distribution transformers, isolating switches, The reactive power compensation capacitor, a metering device, and some auxiliary facilities generally adopt a closed-loop design and run in parallel. Its structure is radial. The structure changes from a radial structure to a multi-power supply structure, and the magnitude, flow direction, and distribution characteristics of the short-circuit current all change.

 

6.

Why is photovoltaic power a green and low-carbon energy?

Photovoltaic power generation has significant energy, environmental protection, and economic benefits, and is one of the highest-quality green energy sources. Installing a 1 kilowatt photovoltaic power generation system under the average sunshine conditions in my country can generate 1200 kilowatt-hours of electricity in one year, which can reduce the use of coal (standard coal) According to the research results of the World Wide Fund for Nature (WWF): In terms of the effect of reducing carbon dioxide, installing a photovoltaic power generation system of 1 square meter is equivalent to planting 100 square meters of trees. Currently, renewable energy such as photovoltaic power generation is being developed. Energy is one of the effective means to fundamentally solve environmental problems such as smog and acid rain.

 

7.

What do you think of the news that "a large amount of energy is consumed in the production of photovoltaic cell modules"?

Photovoltaic cells do consume a certain amount of energy in their production process, especially in the three links of industrial silicon purification, high-purity polysilicon production, monocrystalline silicon rod, and polycrystalline silicon ingot production. Energy can be continuously generated within. It is estimated that under the average sunshine conditions in my country, the energy return of the photovoltaic power generation system in the whole life span exceeds its energy consumption by more than 15 times. The energy recovery period of a 1 kW rooftop photovoltaic grid-connected system installed at an optimal inclination angle in Beijing is 1.5-2 years, which is much lower than the service life of the photovoltaic system. That is to say, the electricity generated by the photovoltaic system in the first 1.5-2 years is used to offset the energy consumed in its production and other processes, and the energy emitted after 1.5-2 years is pure output, so photovoltaic cells should be evaluated from the perspective of the entire life cycle energy consumption.

 

8.

What do you think of the news that "the production of photovoltaic cell modules will produce a lot of pollution?"

The production of photovoltaic cell modules includes polysilicon, silicon ingots, photovoltaic cells, and photovoltaic modules. The reports of related pollution mainly refer to the raw materials of photovoltaic modules, by-products produced in the production of high-purity polysilicon, and the production of high-purity polysilicon. Mainly use the improved Siemens method, which converts metallurgical grade silicon into trichlorohelium silicon, and then reduces it to solar grade polysilicon by adding hydrogen. In addition, silicon chloride will be formed as a by-product, and silicon tetrachloride will decompose into silicic acid when it meets humid air. Hydrogen chloride, if not handled properly will cause pollution problems, but the improved Siemens method adopted by China's polysilicon production enterprises can achieve closed-loop production, and the by-product silicon tetrachloride and tail gas can be recycled to achieve clean production. In December 2010, the state issued the "Polysilicon Industry Access Conditions", which stipulated that the recovery and utilization rates of silicon tetrachloride and chlorine in the reduction tail gas should not be lower than 98.5% and 99%, so the mature improved Siemens production technology fully meets the environmental protection requirements. There will be no environmental pollution problems.

 

9.

How much sunlight do we have available? Can it become the dominant energy source in the future?

The solar radiation received by the earth's surface can meet 10,000 times the global energy demand. The average annual radiation received per square meter of the earth's surface varies from 1000-2000KWH depending on the region. According to data from the International Energy Agency, in 4% of the world's deserts Installing solar photovoltaic systems in the world is enough to meet global energy demand. Solar photovoltaics enjoy a broad space for development, and their potential is huge.

According to preliminary statistics, the market potential of photovoltaic power generation in my country is more than 3 trillion kilowatts only by using existing buildings. With technological progress and large-scale application, the cost of power generation will be further reduced, and it will become a more competitive energy supply method, gradually changing from supplementary energy to alternative energy, and it is hoped to become the dominant energy in the future.