The sun light on the semiconductor pn junction to form a new hole - electron pairs in the role of the pn junction electric field, the holes from the n region to the p zone, n area of ??electron flow by p zone connected to the circuit after the formation of current. This is the photoelectric effect of solar cell works.
A solar power generation solar power in two ways, one is tube solar water heater - heat - electricity conversion mode, and the other is the direct conversion of light - electric.
(1) light - heat - electricity conversion mode through the use of thermal energy generated by solar radiation, is usually converted by the solar collectors to absorb the heat of the refrigerant vapor, and then drive a steam turbine power generation. Before a process - thermal conversion process; after a process of heat - electricity conversion process, with the ordinary thermal power. Disadvantage of solar thermal power generation efficiency is low and the high cost, estimated investment of at least than the average fire power plants of 5 to 10 times more expensive. a 1000MW of solar thermal power plants need 20 to $ 2.5 billion investment, average 1kW investment of 2000 to $ 2500. Therefore, only a small scale used in special occasions, large-scale use in the economy is very uneconomical, but also can not compete with the ordinary power plant or nuclear power plants.
(2) light - electric conversion is the use of the photoelectric effect, solar radiation will be converted directly into electrical energy, light - electric conversion device is the solar cell. Solar cell is a photovoltaic effect and solar energy directly converted into electrical energy device, a semiconductor photodiode, when the sun solar powered indoor lights to the photodiode, the photodiode of the sun's light energy into electrical energy, resulting in currents. When many cells in series or parallel can be a relatively large output power of solar cell matrix. Solar cell is a promising new type of power supply, with a permanent, clean, and the flexibility of the three major advantages of solar battery life, as long as there is sun, the solar cells can be an investment in long-term use; and thermal power, nuclear power generation compared to solar cells does not cause environmental pollution; solar cells can be both medium and small, large to medium-sized plant of one million kilowatts, small enough to only a solar battery pack, which is unmatched by other power.