Photovoltaic industry is technical branch concerning the process of direct exchange of sunlight into electric energy. The name is derived from the words photo (light) and volt (electric tension unit). The process of transformation takes place in photovoltaic cell.
Solar cells (used in solar power) and light-sensitive diodes use a variant of the photoelectric effect, but not ejecting electrons out of the material. In semiconductors, light of even relatively low energy, such as visible photons, can kick electrons out of the valence band and into the higher-energy conduction band, where they can be harnessed, creating electric current at a voltage related to the band gap energy.
Photovoltaic industry is a very dynamic branch. It was discovered by Alexander Edmond Becquerel in 1839. In 1958 the first solar cells were used for electric energy production in cosmic programs and since then it has been its integral part.
There are various types of solar panels. Monocrystalline panels (14-17% efficiency) and polycrystalline panels (12-15% efficiency) are the most common in these days. The cheaper panels on the basis of amorphous silicon (5-9% efficiency) are less and less popular. The newest solar panels with efficiency up to 28% are being tested in laboratories and are being prepared for mass production. The most efficient commercially produced panels have efficiency 20%.
The solar panels power output depends on direct sunlight and therefore the output is expressed by peak output (the ideal conditions), with sunshine intensity 1 000 W/m2. The cell with 17 % efficiency and size of 1 m2 peak output 170 Wp.
Inverter
Solar panels produce direct current (DC), which must be alternated for the purpose of distribution into alternate current (AC). The unit, where the alternation takes place is called inverter. Inverter is the control center of the solar power station, which reports information about the amount of produced energy, or faults etc. through gsm or internet.
Solar power in Europe
Obviously, the solar energy highly depends on the sunlight. The amount of produced energy is determined by several characteristics: season, geographical latitude etc. Southern states of Europe offer the best conditions for solar parks, but the newest panels can operate with high efficiency even during cloudy and foggy weather. That makes solar power stations commercially interesting even in the countries, where the sunny days are less often than in the southern states.
