Within the course of technological development that solar photovoltaic field has experienced in the last 25 years, various commercially applicable technologies have emerged. The shortage of silicon and high capital cost of photovoltaic systems has been a major driving force for these advancements. Today, we see thin film materials like CIGS (Cadmium-Indium-Gallium-Selenide) and amorphous silicon giving equal competition to the long established crystalline silicon market.
Commercially used solar photovoltaic technologies:
Silicon Crystalline Cells
The cells uses crystalline silicon as the semiconductor in a thick and single layer of ribbon or ingot. On the basis of generation process, theses cells are further of two types:
- Monocrystalline Cells, which uses mono-crystals of silicon, produced from pure silicon by float zone method or Czochralski method, forming perfect crystals. It delivers an efficiency of 15-18%.
- Polycrystalline Cells, which uses the silicon in form of imperfect crystals, formed by heating and cooling of pure silicon to get the fibrous structured silicon. Efficiency delivered by same occupies a range of 13-15%.
Thin Film Cells
These cells were created with aim to reduce costs of the cells by using the semiconductor in the wafer or thin layer form. These cells are cheaper but occupy more space for equivalent power generation.
Two major categories are:
- Amorphous Silicon which is made of non-crystalline or powder form of the silicon. The added advantage of these cells is its usage on flexible surfaces like plastic. Their efficiency ranges from 5-8 %.
- Another category makes use of material other than silicon in order to reduce manufacturing cost. Popular material available commercially include Cd-Te, CIGS and Cu/ In/ di-Se. Efficiency ranges from 9-11%.
These are made of different semiconductor layers stacked on one another. Since one material absorbs light of a particular wavelength, the underneath material absorbs the other and so on thereby making the best use of solar spectrum. Through this filtering process and also due to the maximum internal reflection in-between the gap, the complete solar spectrum is efficiently utilized. It usually uses concentrating structures and often designated as concentrating PV cell.
|Silicon Crystalline PV||
|Thin film PV||
|Solar Thermal Concentrating||
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