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Presentation photovoltaic panels

History

Photovoltaic efect is the main underlying physical proces building techjnologies solar cells, which convert solar light in electricity.
In 1893 ,Edmund Becquerel , french physicist the age 19 years, discover photovoltaic effect during an experiment with an electrolytic cell made of two metal electrodes. He discovered that certain materials can produce small amounts of electricity when exposed to light.

The first solar cell was built by Charles Fritts which covered semiconductor selenium with a thin film of gold to form a metal semiconductor junction .
The device had an efficiency  of 1 % .Solar cells have become practical use as energy sources after the Ohl Russel , in 1941, has developed technology junction p/n allowed attainment of effective above 5 % by 1950-1960 . Today solar cells developed at laboratory level reached above 20 % efficient .

Modern age of solar technologies came in 1954 at Bell Laboratories who develop experiments with semiconductors , accidentally found that silicon doped with certtain impurities was sensitive to light. Daryl Chapin , Calvin Fuller and Gerald Pearson in 1954 invented the first practical device for converting solar energyj into electricity with an efficiency of 6% first solar cell battery was built In april 1954. First solar panel was used on the Vanguard I satellite launched in march 1958 and was composed of solar cells produced by Hoffman Electronics . This event created interest in producing and launcing geostationary communications satellites supplied with electricity from solar panels .

In 1970 was created first for GaAs heterostructures on or built high efficiency solar cells.
Zhores Alferov  , I. Protasov and V.G. Trofim who created the first heterotranzistor who develop  mobile phones and satellite communications.
The technology-MOCVD –Layer from the vapor phase chemical compounds metaloorganic –developed in 1980 has allowed the development of solar cells on GAAs .
Dual junction cells on GaAs structures in 2007 reached 30 % amo efficiency .

Principle of operation

From a physical  device that converts solar radiation  as light , into electricity is composed of :
  • One cut plate silicon cristal  doped with some metals to form a junction type semiconductor p/n or n/p .
  • Electrodes.
On the two sides of the silicon cristal plate are disposed in form of strips of metal film electrodes for collecting electricity.
The system consists of two junctions , one p/n and n/p.
When the silicon cristal surface is irradiated by light, photons going troughh the cristal atoms  and forming a electrons current. This phenomenon can be observed from the principle diagram below.


principiu functionare

Types of photovoltaic panels

Photovoltaic panels are classified according to the structure of the solar plate so that there are the following types:

MONOCRYSTALINE

panouri fotovoltaice monocristalineMonocrystalline photovoltaic cells differ in that they are made by cutting very thin slices approx. 100-200 micron thickness of silicon single crystals .Color dark black.
Advantages:
  • High yield approx. 24% lab and 16% - 17% in practice.
  • Higher energy production on the same surface of land.
Disadvantaged :
  • Higher cost-price compared to other options.




POLYCRYSTALLINE

panouri fotovoltaice policristalinePolycrystalline solar cells are made from single crystals melted, with the appearance of composite material consisting blue color .
Advantages:
  • Price smaller than the monocrystal.
  • Efficiency of 17% In lab and 12.5% -14.5% in practice.




THIN FILM

panouri fotovoltaice thin filmThin Film cells (thin-film) are constructed by depositing extremely thin layers of semiconductor photovoltaic material support such as glass, stainless steel or plastic, show stable efficiencies range from 7% to 13 %. Thin film materials are used commercially amorphous silicon (a-Si), cadmium telluride (CdTe) and copper-indium-gallium-diselenide (CIGS).
Advantages:
  • There are potentially cheaper to manufacture than (monocrystalline or polycrystalline).
  • Have a greater customer appeal due to design elements because of their uniform appearance .
Disadvantages
  • Present disadvantages such as low efficiency and require conversion large areas of photovoltaic arrays and more material (cables, support structures) to produce the same amount of electricity.

Photovoltaic Systems

Sistem conectat la retea  - grid de mica si medie  putere   - Medium power solution


sisteme fotovoltaice banner

  1. sisteme fotovoltaice schema Photovoltaic panels
  2. inverter
  3. Indicator electricity production
  4. electric meter
  5. consumer
  6. Communication device blue tooth
  7. Internet communications device
  8. three-phase inverter
  9. Panel Network Connection

Sistem conectat la retea –grid

Centrala solara - POWER PLANT

centrala solara
  • Central inverter
  • Medium voltage transformer
  • monitoring controller
  • Central grid connection
  • Control room operator solar plant
  • Field lines of solar panels
  • Medium voltage grid

Sistem autonom off grid

sistem autonom off gridOff grid autonomous system consists of solar panels, inverter, controller, battery batteries
and network customers. If you translate off greed means no network, these systems are used in remote areas where no electricity supply network. The inverter transforms dc current from batteries into AC voltage.The charge controller  loading batteries from photovoltaic cells and determines the optimum time and charge .



SISTEM TRACKING

sistem solar trackingSolar radiation is the morning and afternoon from east to west in winter also has an angle of 20 degrees from the horizontal and 60 degrees in summer. A system consists of steel structure, mechanisms and electronic devices built with solar panels to keep the position most favorable solar radiation, from morning to evening and throughout the year is called tracking system.





sisteme fotovoltaice poza 1sisteme fotovoltaice poza 2sisteme fotovoltaice poza 3sisteme fotovoltaice poza 4


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ELTEX SOLAR a participat in perioada 21-23.11.2012 la "Al V-lea targ international pentru energie al Romaniei"