The sun is a natural source of energy. Every living thing on the earth has the ability to function, and indeed its existence, because of energy directly or indirectly from the sun. Comparing with other traditional energy, there are three main advantages of solar energy:
First, it is the most abundant source of energy available to mankind. It's estimated that over the last 1.1 billion years, the sun has consumed about 2% of its energy, which is an inexhaustible supply.
Second, solar energy is available everywhere on the earth, which can be developed and utilized locally without transportation problems. It is especially valuable for rural areas, islands and remote areas with underdeveloped transportation.
Third, solar energy is a kind of clean energy, in the development and utilization, will not produce waste slag, waste water, waste gas, no noise, not to affect the ecological balance.
Our Earth is about 100 million miles away from the sun. The amount of radiation it intercepts is incredibly small (about three parts per million), a tiny amount of energy that is actually 100,000 times greater than the entire world's current generating capacity. At present, the whole world especially the industrial developed countries begin to feel the shortage of energy, so people begin to turn to solar energy to solve the energy crisis.
Solar energy is a kind of radiant energy, we can not use directly, so we have to convert the sunlight to use it.
At present, the most widely used is the conversion of solar energy into electricity. The process of converting light energy directly into electricity is precisely called the photovoltaic effect. Without the aid of any other mechanical part, the energy in the light is captured by the electrons of the semiconductor device, and electricity is produced. This kind of energy converter, which converts light energy into electricity, is the solar cell. Solar cells, like transistors, are made of semiconductors. Its main material is silicon, but there are also some other alloys. The high-purity silicon used to make solar cells is specially purified. As long as the solar cell is illuminated by sunlight or lights, it can convert light energy into electric energy, so that the current flows from one side to the other side, and generally can emit electricity equivalent to 10% ~ 20% of the received light energy.
At present, the application of solar cells from the military field, aerospace field into industrial, commercial, agricultural and other industries and communication, household appliances and public facilities, especially in remote areas, mountains, deserts, islands and rural areas to save the cost of high power transmission lines. But at this stage, it is expensive, costing tens of thousands of dollars to generate a kilowatt of electricity, so large-scale use remains economically limited.