Functional characteristics of solar photovoltaic power generation

[Abstract]

The reason why the solar photovoltaic industry can maintain a high growth trend is that solar energy, as a renewable and clean energy source, is the development direction of new energy in the world. In the future world energy structure, renewable energy, especially solar photovoltaic power generation will occupy an increasing proportion. In 2030, solar power will account for 10% of the global energy structure. By 2050, this proportion will rise to 25%. It will reach 64% by 2100.

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 (1) The basic structure of the sun

Solar energy is a sphere composed of hot gases, mainly composed of hydrogen and helium, of which hydrogen accounts for 80% and niobium accounts for 19%.

(2) Solar constant

The solar constant refers to the value of solar radiant energy per unit area and unit time in a plane perpendicular to the sun's rays above the Earth's atmosphere, in addition to the average distance between the sun's earth. This value is a constant, generally 1367 watts/m2. (4920 kJ/m2).

(3) Solar radiant energy and solar energy reaching the earth

The energy released by the entire sun every second is enormous, as high as 3.826 × 1033 ergs or 37.3 × 106 megajoules, equivalent to the energy emitted by burning 128 million tons of standard coal per second.

The energy of solar radiation reaching the Earth's land surface is about 17 trillion kilowatts, accounting for only 10% of the total radiation reaching the outer surface of the Earth's atmosphere. Even so, it is equivalent to 35,000 times the total energy consumption in the world in one year.

(4) China's solar energy resources

China's solar energy resources are very rich. There are more than two-thirds of the country's regions. The total annual radiation is more than 5.02 million kJ/m2, and the annual sunshine hours are over 2000 hours.

(5) The characteristics of solar energy

The advantages of solar energy

As a new energy source, solar energy has three major advantages compared to conventional energy:

First, it is the most abundant energy available to humans. It is estimated that in the long period of 1.1 billion years, the sun consumed 2% of its own energy, which can be said to be inexhaustible.

Second, on the earth, wherever there is solar energy, it can be developed and utilized on the spot. There is no transportation problem, especially for rural areas, islands and remote areas with underdeveloped traffic.

Third, solar energy is a clean energy source. When it is developed and utilized, it will not produce waste residue, waste water, waste gas, no noise, and will not affect the ecological balance.

Shortcomings of solar energy

The use of solar energy has its drawbacks:

First, the energy flow density is low, and the sunshine is good. The energy of 1 square meter on the ground receives only about 1 kilowatt. It is often necessary to have a relatively large light collecting surface to meet the requirements of use, so that the device has a large area, a large amount of materials, and an increased cost.

Second, the atmosphere has a large impact, which brings a lot of difficulties to the use.

(6) Technical field of solar energy utilization

There are three major technical fields in which humans directly use solar energy, namely, photothermal conversion, photoelectric conversion, and photochemical conversion. In addition, there are energy storage technologies.

There are many products for solar thermal conversion technology, such as water heaters, water heaters, dryers, heating and cooling, greenhouses and solar houses, solar cookers and high temperature furnaces, desalination plants, water pumps, thermal power plants and solar medical devices.

[Conclusion]

In recent years, the international photovoltaic power generation has developed rapidly. More than 10 megawatt-scale photovoltaic power generation systems and 6 megawatt-scale connected photovoltaic power plants have been built in the world.

The United States was the first country to develop a development plan for photovoltaic power generation. In 1997, the “Million Roof” project was proposed. Japan launched the new sunshine program in 1992. By 2003, Japan's PV module production accounted for 50% of the world's total, and four of the world's top 10 manufacturers were in Japan. The German New Renewable Energy Law stipulates the on-grid price of photovoltaic power generation, which greatly promotes the development of the photovoltaic market and industry, making Germany the fastest growing country in the world after Japan. 

Switzerland, France, Italy, Spain, Finland and other countries have also developed photovoltaic development plans, and invested heavily in technology development and accelerated industrialization.