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Sunday, October 27, 2019

What is Concentrator Photovoltaic (CPV) Technology? - Benefits and Challenges

Concentrator Photovoltaic Technology
Concentrator photovoltaic (CPV) solar technology which will shape the future of solar energy

What is Concentrator Photovoltaic (CPV) Technology? - Benefits and Challenges

Overview
Concentrator photovoltaic (CPV) technology is an outstanding high-efficiency system in the world of photovoltaic solar technologies. CPV technology uses optical instruments such as curved mirrors or lenses to focus a large amount of sunlight onto a small area of multi-junction (MJ) solar cells (photovoltaic panels) to generate electricity. When compared with non-concentrated solar modules, concentrator photovoltaic (CPV) systems can reduce the cost of solar cells because of the reduced space required for photovoltaic materials. This technology has many benefits but there are some challenges regarding manufacturing costs and other perspectives.


What is Concentrator Photovoltaic (CPV)?

Concentrator photovoltaic (CPV) is a photovoltaic technology that uses optical instruments such as lenses or curved mirrors to concentrate a large amount of sunlight onto a small area of highly efficient photovoltaic (PV) (multi-junction-MJ) solar cells and converts visible light into direct current (DC) electricity. Because of the low amount of photovoltaic materials required, concentrator photovoltaic technologies can use the most cost-effective tandem solar cells.
Concentrating photovoltaic systems are classified according to their solar concentration, and measured in "suns" (the square of the magnification). Concentrator photovoltaic (CPV) systems can be regarded as telescopes oriented towards the position of the sun, feeding the cell with concentrated light. In CPV system designs, the magnification ratio varies considerably, it has been developed into three categories: • + Low concentration (LCPV), where the magnification ratio is less than 10X. • + Medium concentration (MCPV), between 10X and 100X. • + High concentration, where the ratio is higher than 100X but is usually less than X 1000.

Concentrator Photovoltaics vs. Conventional Photovoltaics

Concentrating photovoltaics (CPV) system converts optical energy into electrical energy in the same way as conventional photovoltaic technology. The difference between concentrator photovoltaic technology and conventional photovoltaic technology is the addition of an optical instrument system in CPV technology to focus a large amount of sunlight on each cell. In order to concentrate sunlight on the limited area of photovoltaic panels, concentrator photovoltaic systems require more money to be spent on concentrated optical instruments (lenses or mirrors) and sometimes on solar tracking and cooling systems. Because of these additional costs, concentrator photovoltaic (CPV) technology is currently much less common than non-concentrated solar modules. Concentrator photovoltaics technology is increasingly recognized as the most promising technology to meet the energy challenges facing the world.
Concentrator photovoltaics (CPV) panels have become a recognized science since the 1970s, but have only recently become commercially marketable, the latest technology in solar energy sector.



Benefits of Concentrator Photovoltaic (CPV) Technology

The most important scientific and commercial benefit generated by concentrating photovoltaic technology is mainly due to the huge energy yield of these cells, especially in high-radiation areas. This benefit is also due to the large potential of these cells in reducing costs compared not only with other solar technologies but also with other renewable energy sources. These characteristics can make the concentrator photovoltaics technologies the most widely used solar carriers in future power plants. The solar added value represents a high degree of technical specialization in understanding CPV technologies and functional principles. Concentrating photovoltaics (CPV) modules typically use multi-junction (MJ) solar cells. These cells are actually composed of many solar cells - called sub-cells - connected in series and made of different semiconductors.
The advantage of this configuration is that it allows increased energy use from photons in the solar spectrum, providing the system with a higher degree of conversion of light into DC electricity. Furthermore, multi-junction (MJ) solar cells can be especially designed and calibrated for a specific optical spectrum in order to perform a more efficient light conversion.
Currently, the most commonly used multi-junction cell (MJ) is the three-link cell, which typically exhibits a conversion rate efficiency of more than 40 percent, which is much higher than any other commercially used photovoltaic panel technology.
All CPV systems include an optical focus instrument and a solar cell. With the exception of very low concentrations, a solar tracking system is also essential.  Low concentration systems often include a simple reflection booster that can increase solar electricity production by more than 30 percent of photovoltaic systems without concentrations.

Challenges Regarding Concentrator Photovoltaic Technology

The challenges for many solar technologies are to get CPV products out of the laboratory and take them to market. The most important thing that will make CPV technology successful or fail is the ability to manufacture products in the required quantity while keeping costs down.
In concentrating photovoltaic systems, the optical light concentrators are used to increase the incidental capacity of solar cells. The semiconductor properties allow solar cells to operate more efficiently in concentrated light, as long as the temperature of the cell junction is maintained by appropriate heat sinks. The solar cell area is relatively small, thus requires the use of more sophisticated, more expensive, multi-junction solar cells and the systems need careful tracking to keep the light focused on solar cells as the sun moves during the day. This adds additional system costs and complexities and also increases the maintenance load during operation.
If companies intend to manufacture photovoltaic products, they face many challenges because the photovoltaic process requires the use of advanced materials, optical alignment of various stages with micrometer precision, the integration of microscopic systems in large areas, the manipulation, and interconnection of thousands of elements per square meter.  Therefore, alternative renewable energy storage technologies should be explored to achieve small CPV units at low manufacturing cost.



Conclusion
 The research-developed multi-junction photovoltaic cells are currently 44 percent efficient and are constantly increasing to 50 percent in the coming years. Scientific journals are full of reports on recent developments in solar cell efficiency. Although this is very encouraging, it is difficult to know how well these innovations are doing outside the laboratory and when they will succeed in the market. The concentrating photovoltaic technology market seems ready to take off and grow rapidly due to feed-in tariff laws adopted in many sunny countries.

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