We know in today’s market different types of solar cells are available, mono-crystalline, Poly Crystalline, amorphous silicon (α-Si), copper indium gallium selenide (CIGS), and cadmium telluride (CdTe), Crystalline silicon solar cell, Thin film solar cell, and multi-junction solar cell.
What we understand from the above names is that the solar cells can be manufactured from different materials and by different process technologies.
The name of a particular solar cell or solar cell technology depends on the name of the material used in that particular technology. properties of different materials used in different type of solar cells are different. hence different types of solar cells have different values of solar cell parameters like efficiency, short circuit current, open circuit voltage, and fill factor.
In this article we will learn the basics of various solar photo voltaic technologies, solar cell types, materials used and various parameters of these solar cells.
Types of Solar Photo voltaic technologies
Crystalline Solar cells :
These are traditional solar cells made up of silicon crystals. These are usually flat-plate, and generally are the most efficient. These can be mono-crystalline or poly crystalline or multi crystalline in nature.
Materials used to produce solar cells of this type are mono crystalline silicon and poly crystaline silicon.
Thin film Solar cells :
These are second-generation solar cells. Thsese are called thin-film solar cells because they are made from amorphous silicon or nonsilicon materials such as Cadmium telluride or Amorphous silicon, or Copper-Indium-Gallium-Selenide(CIGS) or de-sensitized solar cells.
Thin film solar cells use layers of semiconductor materials only a few micrometers thick. Because of their flexibility, thin film solar cells can be used in rooftops and in tiles, building facades, or the glazing for skylights.
Materials used to manufacture thin-film solar cells are Amorphous silicon, cadmium and tellurium, and copper, indium, gallium, selenium accordingly.
Multi-junction Solar cells :
Multi-junction solar cells consist of multiple thin film solar cells, with one solar cell grown on top of another. Each layer has a different band gap energy to allow it to absorb electromagnetic radiation over a different portion of the spectrum.
Multi-junction solar cells were originally developed for special applications such as satellites and space exploration, but are now used increasingly in terrestrial Concentrator photovoltaics (CPV), an emerging technology that uses lenses and curved mirrors to concentrate sunlight onto small, highly efficient multi-junction solar cells.
multi-junction solar cells are generally made up of Galliium, Arsenic, Indium, Pohsphorous, Germanium etc.
Efficiency of Solar Cells
The efficiency of solar cells varies from one technology to other technology and from one manufacturer to other manufacturer.
Crystalline solar cells have an efficiency of 14% to 16%, whereas the thin-film solar cells give an efficiency of 6 to 11 %.
Among all the thin film solar cell types, Amorphos solar cells give efficiency of 6-9% where as CadmiumTelluride solar cells and Copper-Indium-Gallium-Selenium solar cells(CIGS) give an efficiency of 8-11%.
Multi-junction solar cells are the most efficient types. They generally have an efficiency of 30 -35%.
Typical Solar cell parameters of commercial solar cells
|Solar cell Type||Efficiency(%)||Cell Area(in cm²)||Output Voltage(Voc)||Output Current(Ioc)||Fill Factor(FF)(in %)|
|Mono-crystalline Silicon||14-17||5-156||0.55 – 0.68 V||30 – 38||70 – 78|
|Poly or Multi-crystalline silicon||14-16||5-156||0.55 – 0.65 V||30 – 35||70 – 76|
|Amorphous Silicon||6-9||5-200||0.70 – 1.1 V||8 – 15||60 – 70|
|Cadmium Teluride||8-11||5-200||0.8 – 1.0 V||15 – 25||60 – 70|
|Copper-Indium-Gallium-selenide(CIGS)||8-11||5-200||0.5 – 0.7 V||20 – 30||60 – 70|
|GAlium Indium Phosphide/ Galium Arsenide/ germaniumc(GaLnP / GaAs/Ge)||30-35||1-4||1.0 – 2.5 V||15 – 35||70 – 85|