The operation of the CPV is based on solar cells made of compound semiconductors such as gallium arsenide, using solar radiation with an efficiency of 40%, double the conventional. However, as the materials needed are very expensive, very small cells are installed (two millimeters square and two inches square). To counter this small size, used various means such as mirrors, lenses, prisms, etc.., Which concentrate sunlight on the cells and extended to a thousand times.
Concentration photovoltaic technology (CPV) uses the solar radiation with an efficiency of 40%, double that of conventional solar cells
The CPV is one more example of the many practical applications that have space research. This technology is used for years in the panels of the satellites and spacecraft, where plates are required to obtain maximum solar energy in the minimum possible surface. United States (U.S.) was a pioneer in the creation of these cells, while from the 80’s decline was its drive to focus on the aerospace industry.
At present, the increasing development of renewable energy is returning the interest in this technology. Proponents claim that with technological advancement and a proper legal framework, the CPV can be competitive in a few years. For example, CPV Today, an initiative created to generalize this scheme, envisaged that the third generation of new cells reach an efficiency of 50% by 2015, thus helping to decrease its cost by 62%.
When the market these plates, but can be used individually as conventional photovoltaic systems, with a power of a few kilowatts (KW), its promoters believe that today the main economic output is the use on an industrial scale. In this case, the idea would be to build plants with a lot of solar power and thereby achieve above 100 megawatts (MW). In this way, we could supply the energy to the grid, or use it to produce hydrogen, one of the great hopes for clean energy.
Besides the U.S., Germany and Spain are the countries most advanced in the world in this field. For example, in 2006 established the Institute of Concentration Photovoltaic Systems (ISFOC). Headquartered in Puertollano (Ciudad Real) is an R & D center in the world pioneer who has launched, according to its makers, a pilot CPV installation of three MW.
For his part, as those responsible for the ISFOC, there are several plants that are already operating in Spain are connected to the network with a total power of 15 MW. These plants are tested in the various technologies available, with a concentration based on both silicon cells and in cells with high efficiency. For example, the Photon Guascor, with financial support from the Institute for the Diversification and Saving of Energy (IDEA), put up the first commercial installation of its kind in Europe.
Outside of Spain, but with Spanish participation, the project NACIR is another interesting initiative in the field of CPV. Its aim is to use this technology in the countries of North Africa, with unbeatable position to take advantage of sunlight. The project, launched this year, is scheduled to run for four years and has a budget of over seven million euros, partly financed by the European Commission. Among its main challenges highlighted in the installation of a system of Morocco SVC connected to the mains, an autonomous system of water pumping and irrigation in Egypt and the creation of a database to increase efficiency and reduce costs.
The project also NACIR emerges through the collaborative efforts of three bands: university-industry-institution, as part of the Solar Energy Institute of the Polytechnic University of Madrid, the ISFOC, Fraunhoffer Institute for Solar Energy in Germany, companies Concentrix Solar (Germany) and Isofoton (Spain), the Moroccan National Electricity (ONE) and the Ministry of Water Resources of Egypt. Besides NACIR, ISFOC makers explained that they expect to realize over 2009 various collaborative projects in the Middle East, Asia and U.S.
Disadvantages of concentration photovoltaics
The drivers of the CPV today recognize that this technology is still in a pre-condition. Also, the technology presents a number of characteristics that limit their generalization. For example, the cells function properly only on clear days and with direct radiation, which reduces its use to optimally very sunny and located on the equator of the planet. For example, since the ISFOC explained that one of the criteria for choosing Puertollano as a test bed was the high amount of direct radiation.
However, the disadvantage of lack of sunlight prevents the use of solar followers two axes high precision, but of course makes the final product. Moreover, while there are followers of concentration for its location on roofs, their drivers do not consider that option is more interesting for this technology. Moreover, the efficiency losses of up to one thousand times the sun’s light on the hub are also important, although lower than other solar technologies, such as the foil.
As costs of CPV, ISFOC responsible for ensuring that at present are similar to those of conventional photovoltaics, although they estimate that in the short term, technology development and market growth, coupled with legislation appropriate, will place the cost of generating electricity under the CPV conventional photovoltaics.