The solar PV is a power source that produces electricity from renewable sources [ 1 ] obtained directly from solar radiation by a device semiconductor called photovoltaic cell , [ 2 ] or by a metal deposition on a substrate called a thin film solar cell . [ 3 ]
This type of energy is used mainly to produce electricity on a large scale through distribution networks , although it can also power countless applications and autonomous devices, as well as supply mountain shelters or homes isolated from the electricity grid . Due to the growing demand for renewable energy , the manufacture of solar cells and photovoltaic installations has advanced considerably in recent years. [ 4 ] [ 5 ]They began to be mass produced in 2000, when German environmentalists and the Eurosolar organization obtained funding for the creation of ten million solar roofs. [ 6 ]
Economic incentive programs, first, and later, photovoltaic self - consumption systems and net balance without subsidies , [ 7 ] have supported the installation of photovoltaics in a large number of countries. [ 8 ] As a result, photovoltaic solar energy has become the third most important renewable energy source in terms of installed capacity globally, after hydroelectric and wind energy . At the end of 2018, the total installed power worldwide reached 500 GW of photovoltaic power, and only in 2018 100 GW were installed.
Photovoltaic energy does not emit any type of pollution during its operation, helping to avoid the emission of greenhouse gases . [ 1 ] Its main disadvantage is that its production depends on solar radiation, so if the cell is not aligned perpendicular to the Sun between 10-25% of the incident energy is lost. Due to this, in grid connection plants the use of solar trackers has become popular to maximize energy production. [ 11 ]Production is also affected by adverse weather conditions, such as lack of sun, clouds or dirt that is deposited on the panels. [ 12 ] [ 13 ] This implies that to guarantee power supply is necessary to supplement this energy with other energy sources Manageable plants based on burning fossil fuels , hydropower or nuclear energy .
Thanks to technological advances, sophistication and economies of scale , the cost of solar photovoltaic energy has been reduced steadily since the first commercial solar cells were manufactured, [ 14 ] increasing efficiency, and achieving that its average cost of electricity generation is already competitive with conventional energy sources [ 15 ] in a growing number of geographic regions, reaching grid parity . [ 16 ] [ 17 ] [ 18 ]Currently the cost of electricity produced in solar installations is between $ 0.05-0.10 / kWh in Europe , China , India , South Africa and the United States . [ 19 ] In 2015, new records were reached in projects in the United Arab Emirates ($ 0.0584 / kWh), Peru ($ 0.048 / kWh) and Mexico ($ 0.048 / kWh). In May 2016, a solar auction in Dubai fetched a price of $ 0.03 / kWh. [ 19 ] In 2020, the record figure of $ 0.016 / kWh was reached in Saudi Arabia. [ 20 ]
The term "photovoltaic" began to be used in the United Kingdom in 1849. [ 21 ] It comes from the Greek φώς: phos , which means "light", and from -voltaic , which comes from the field of electricity, in honor of the Italian physicist Alejandro Volta . [ Note 1 ]
The photovoltaic effect was first recognized about ten years earlier, in 1839, by the physical French Alexandre-Edmond Becquerel , [ 22 ] [ 23 ] but the first solar cell was not manufactured until 1883. Its creator was Charles Fritts , who coated a sample of semiconductor selenium with gold leaf to form the junction. This early device had an efficiency of less than 1%, but it demonstrated in a practical way that, indeed, producing electricity with light was possible. [ 24 ] Studies conducted in the nineteenth centuryby Michael Faraday , James Clerk Maxwell , Nikola Tesla, and Heinrich Hertz on electromagnetic induction , electric forces, and electromagnetic waves , and above all, the work done by Albert Einstein in 1905, for which he was awarded the Nobel Prize in 1921, provided the theoretical and practical basis of the photoelectric effect , [ 25 ] which is the foundation of the conversion of solar energy into electricity.
When a doped semiconductor is exposed to electromagnetic radiation , an incident photon strikes an electron and rips it off, creating a hole in the atom. Normally, the electron quickly finds another hole to fill it again, and the energy provided by the photon is therefore dissipated as heat. The principle of a photovoltaic cell is to force electrons and holes to move towards the opposite side of the material instead of simply recombining in it: thus, a potential difference will be produced , and therefore, voltage between the two parts of the material. material, as in a pile .
- The top layer of the cell, which is made up of n-type doped silicon . [ note 2 ] In this layer, there are a greater number of free electrons than in a layer of pure silicon, hence the name of doping n, negative. The material remains electrically neutral, since both the silicon atoms and those of the doping material are neutral: but the crystal lattice globally has a greater presence of electrons than in a pure silicon lattice.
- The bottom layer of the cell, which is made up of p-type doped silicon . [ note 3 ] This layer therefore has a lower average number of free electrons than a layer of pure silicon. The electrons are bound to the crystal lattice, which is consequently electrically neutral, but has positive (p) holes . Electrical conduction is ensured by these charge carriers, which travel throughout the material.
At the time of pn junction creation, the free electrons from the n shell instantly enter the p shell and recombine with the holes in the p region. There will thus be throughout the life of the junction, a positive charge in the n region along the junction (because electrons are missing) and a negative charge in the p region along the junction (because the holes have disappeared); the set forms the «Space Charge Zone» (CEZ) and there is an electric field between the two, from n to p. This electric field makes the CEZ a diode , which only allows current to flow in one direction: electrons can move from region p to n, but not in the opposite direction,holes do not pass more than from n to p.
In operation, when a photon strikes an electron from the matrix, creating a free electron and a hole , under the effect of this electric field each one goes in the opposite direction: the electrons accumulate in the n region (to become a negative pole) , while the holes accumulate in the p-doped region (which becomes the positive pole). This phenomenon is more effective in the CEZ, where there are almost no charge carriers (electrons or holes ), since they are canceled, or in the immediate proximity to the CEZ: when a photon creates an electron-hole pair, they separate and it is unlikely to find its opposite, but if creation takes place farther from the junction, the electron (converted into a hollow) maintains a great opportunity to recombine before reaching zone n. But CEZ is necessarily very thin, so it is not useful to thicken the cell. [ note 4 ] Indeed, the thickness of layer n is very small, since this layer is only needed basically to create the CEZ that makes the cell work. On the other hand, the thickness of the layer p is greater: it depends on a compromise between the need to minimize electron-hole recombinations , and on the contrary allow the capture of the largest number of photons possible, for which a certain minimum thickness is required.
In short, a photovoltaic cell is the equivalent of a power generator to which a diode has been added . To achieve a practical solar cell, it is also necessary to add electrical contacts (which allow the energy generated to be extracted), a layer that protects the cell but allows light to pass through, an anti-reflective layer to guarantee the correct absorption of photons , and other elements that increase its efficiency.
First modern solar cell
The American engineer Russell Ohl patented the modern solar cell in 1946, [ 26 ] although other researchers had advanced in its development previously: the Swedish physicist Sven Ason Berglund had patented in 1914 a method that tried to increase the capacity of solar cells. photosensitive cells, while in 1931, the German engineer Bruno Lange had developed a photocell using silver selenide instead of copper oxide . [ 27 ]
The modern era of solar technology did not come until 1954, when researchers Americans Gerald Pearson, Calvin Fuller and Daryl S. Chapin, of Bell Labs , [ 28 ] discovered accidentally that semiconductor silicon doped with certain impurities were very sensitive to light. These advances contributed to the manufacture of the first commercial solar cell. They employed a diffuse p-n silicon junction, with a solar energy conversion of about 6%, an achievement compared to selenium cells that hardly reached 0.5%. [ 29 ] [ 30 ]
Later the American Les Hoffman, president of the Hoffman Electronics company, through his semiconductor division was one of the pioneers in the manufacture and large-scale production of solar cells. Between 1954 and 1960, Hoffman managed to improve the efficiency of photovoltaic cells up to 14%, reducing manufacturing costs to achieve a product that could be marketed. [ 31 ]
First applications: space solar energy
At first, photovoltaic cells were used in a minority way to electrically power toys and in other minor uses, since the cost of producing electricity by these primitive cells was too high: in relative terms, a cell that produced a watt of energy by Sunlight could cost $ 250 , compared to $ 2 to $ 3 for a watt from a coal- fired power plant .
Photovoltaic cells were rescued from oblivion thanks to the space race and the suggestion of using them in one of the first satellites to orbit the Earth . The Soviet Union launched its first space satellite in 1957 , and the United States would follow a year later. The first spacecraft to use solar panels was the North American Vanguard 1 satellite , launched in March 1958 (today the oldest satellite still in orbit). Solar cells created by Peter Iles in an effort spearheaded by the Hoffman Electronics company were used in its design. [ 32 ]The photovoltaic system allowed it to continue transmitting for seven years while the chemical batteries were depleted in just 20 days. [ 33 ]
In 1959, the United States launched the Explorer 6 . This satellite had installed a series of solar modules, supported on external structures similar to wings, made up of 9600 solar cells from the Hoffman company. [ 31 ] This type of device later became a common feature of many satellites. There was some initial skepticism about the operation of the system, but in practice solar cells proved to be a great success, and they were soon incorporated into the design of new satellites.
A few years later, in 1962 , the Telstar became the first communications satellite equipped with solar cells, capable of providing a power of 14 W . [ 34 ] This milestone generated great interest in the production and launch of geostationary satellites for the development of communications, in which the energy would come from a device for capturing sunlight. It was a crucial development that spurred research by some governments and prompted the improvement of photovoltaic panels . [ 35 ]Gradually, the space industry turned to the use of gallium arsenide (GaAs) solar cells , due to their higher efficiency compared to silicon cells. In 1970 the first highly efficient gallium arsenide heterostructure solar cell was developed in the Soviet Union by Zhorés Alfiórov and his research team. [ 36 ] [ 37 ]
As of 1971, the Soviet space stations of the Salyut program were the first manned orbital complexes to obtain their energy from solar cells , coupled in structures to the sides of the orbital module, [ 38 ] like the North American station Skylab , few years later. [ 39 ]
In the 1970s, after the first oil crisis , the United States Department of Energy and the NASA space agencythey began the study of the concept of solar energy in space, which sought to supply terrestrial energy through space satellites. In 1979 they proposed a fleet of satellites in geostationary orbit, each of which would measure 5 x 10 km and produce between 5 and 10 GW. The construction involved the creation of a large space factory where hundreds of astronauts would work continuously. This gigantism was typical of an era in which the creation of great space cities was projected. Leaving aside the technical difficulties, the proposal was rejected in 1981 for implying a crazy cost. [ 40 ] In the mid-1980s, with oil again at low prices, the program was canceled. [ 41 ]
However, photovoltaic applications on space satellites continued to develop. The production of equipment for the chemical deposition of metals by organic vapors or MOCVD ( Metal Organic Chemical Vapor Deposition ) [ 42 ] did not develop until the 1980s, limiting the capacity of companies in the manufacture of gallium arsenide solar cells. . The first company to manufacture solar panels in industrial quantities, from simple GaAs junctions, with an efficiency of 17% in AM0 ( Air Mass Zero ), was the North American Applied Solar Energy Corporation (ASEC). The cells double bondthey began their production in industrial quantities by ASEC in 1989, accidentally, as a consequence of a change from GaAs on GaAs substrates, to GaAs on germanium substrates .
Photovoltaic technology, although it is not the only one in use, continues to predominate in the early 21st century in Earth-orbiting satellites. [ 43 ] For example, probes Magellan , Mars Global Surveyor and Mars Observer , the NASA , photovoltaic panels used, [ 44 ] [ 45 ] [ 46 ] and the Hubble Space Telescope , [ 47 ] in orbit around the Earth . TheInternational Space Station , also in Earth orbit, is equipped with large photovoltaic systems that feed the entire space complex, [ 48 ] [ 49 ] to equal that once the space station Mir . [ 50 ] Other space vehicles that use photovoltaics to stock are the probe Mars Reconnaissance Orbiter , [ 51 ] Spirit and Opportunity , robots of NASA on Mars . [ 52 ] 
The Rosetta spacecraft , launched in 2004 in orbit towards a comet as far from the Sun as the planet Jupiter (5.25 AU ), also has solar panels; [ 54 ] previously, the most distant use of space solar energy had been that of the Stardust probe , [ 55 ] at 2 AU . Photovoltaic energy has also been used successfully in the European unmanned mission to the moon , SMART-1 , powering its Hall effect thruster . [ 56 ]The Juno space probe will be the first mission to Jupiter to use photovoltaic panels instead of a radioisotope thermoelectric generator , traditionally used in space missions outside the Solar System . [ 57 ] The potential of photovoltaics to equip spacecraft that orbit beyond Jupiter is currently being studied. [ 58 ]
First land applications
Since its appearance in the aerospace industry , where it has become the most reliable means of supplying electrical power in space vehicles , [ 59 ] photovoltaic solar energy has developed a large number of ground applications. The first commercial installation of this type was carried out in 1966, at the Ogami Island lighthouse ( Japan ), allowing the use of flare gas to be replaced by a renewable and self-sufficient electrical source. It was the world's first lighthouse to be powered by photovoltaic solar energy, and it was crucial in demonstrating the viability and potential of this energy source. [ Sixty ]
Improvements came slowly over the next two decades, with the only widespread use in space applications, where its power-to-weight ratio was greater than that of any competing technology. However, this success was also the reason for its slow growth: the aerospace market was willing to pay any price to get the best possible cells, so there was no reason to invest in lower-cost solutions if this reduced efficiency. Instead, the price of the cells was largely determined by the semiconductor industry; your migration to integrated circuit technologythe 1960s resulted in the availability of larger bars at relatively lower prices. As their price fell, the price of the resulting photovoltaic cells fell by the same amount. However, the cost reduction associated with this increasing popularization of photovoltaics was limited, and in 1970 the cost of solar cells was still estimated at $ 100 per watt ($ / Wp ). [ 61 ]
In the late 1960s, the American industrial chemist Elliot Berman was researching a new method for the production of silicon feedstock from a tape process. However, he found little interest in his project and was unable to obtain the necessary funding for its development. Later, in a chance meeting, he was introduced to a team from the oil company Exxon who were looking for strategic projects 30 years from now. The group had concluded that electric power would be much more expensive in 2000, and believed that this price increase would make new alternative energy sources more attractive., being solar energy the most interesting among these. In 1969, Berman joined Exxon's laboratory in Linden, NJ , called the Solar Power Corporation (SPC). [ 61 ]
His effort was directed in the first place to analyze the potential market to identify the possible uses that existed for this new product, and he quickly discovered that if the cost per watt were reduced from 100 $ / Wpat around $ 20 / Wp there would be a significant demand. Realizing that the "silicon tape" concept could take years to develop, the team began looking for ways to reduce the price to $ 20 / Wp using existing materials. The realization that the existing cells were based on the standard semiconductor manufacturing process was a first advance, even if it was not an ideal material. The process began with the formation of a silicon ingot, which was cut transversely into discs called wafers. Subsequently, the wafers were polished and then, for their use as cells, they were coated with an anti-reflective layer. Berman found that rough cut wafers already had a perfectly valid anti-reflective front surface,electrodes directly on this surface, two important steps in the cell manufacturing process were eliminated. [ 61 ]
His team also explored other ways to improve cell assembly in arrays, eliminating expensive materials and manual wiring previously used in space applications. His solution consisted of using printed circuits on the back, acrylic plastic on the front, and silicone glue between the two, embedding the cells. Berman realized that the silicon already on the market was already "good enough" for use in solar cells. Small imperfections that could ruin a silicon ingot (or individual wafer) for use in electronics, they would have little effect in solar applications. Photovoltaic cells could be manufactured from material discarded by the electronics market, which would bring as a consequence a great improvement in their price. [ 61 ]
Putting all these changes into practice, the company began to buy rejected silicon at very low cost from existing manufacturers. By using the largest wafers available, reducing the amount of wiring for a given panel area, and packing them into panels with their new methods, in 1973 SPC was producing panels at $ 10 / Wp and selling them at $ 20 / Wp, reducing the price of photovoltaic modules to a fifth in just two years. [ 61 ]
SPC began to contact the manufacturers of navigation buoys offering the product, but found a curious situation. The main company in the sector was Automatic Power , a manufacturer of disposable batteries. Realizing that solar cells could eat up part of the business and the profits that the battery industry was bringing, Automatic Power bought a solar prototype from Hoffman Electronics to end up cornering it. Seeing that there was no interest from Automatic Power , SPC then turned to Tideland Signal , another battery supply company made up of former Automatic Power managers . [61 ] Tideland brought a photovoltaic-powered buoy to market and was soon ruining Automatic Power's business .
The timing could not be more suitable, the rapid increase in the number of offshore oil rigs and other loading facilities produced a huge market among oil companies. Because Tideland had been successful, Automatic Power then began sourcing its own supply of photovoltaic solar panels. They found Bill Yerkes of Solar Power International (SPI) in California who was looking for a market to sell his product. SPI was soon acquired by one of its most important clients, the oil giant ARCO, forming ARCO Solar. ARCO Solar's factory in Camarillo ( California) was the first dedicated to the construction of solar panels, and was in continuous operation from its purchase by ARCO in 1977 until 2011 when it was closed by the SolarWorld company . [ 61 ]
This situation was combined with the 1973 oil crisis . Oil companies were now heavily funded due to their huge revenues during the crisis, but they were also keenly aware that their future success would depend on some other source of energy. In the following years, the large oil companies began creating a number of solar energy companies, and were for decades the largest producers of solar panels. The companies ARCO, Exxon , Shell , Amoco (later acquired by BP ) and Mobilthey maintained large solar divisions during the 1970s and 1980s. Technology companies also made significant investments, including General Electric , Motorola , IBM , Tyco, and RCA . [ 62 ]
Perfecting the technology
In the decades since Berman's breakthroughs, improvements have reduced production costs to below $ 1 / Wp, with prices below $ 2 / Wp for the entire PV system. The price of the rest of the elements of a photovoltaic installation is now a higher cost than the panels themselves. [ 63 ]
As the semiconductor industry developed into larger and larger ingots, older equipment became available at reduced prices. Cells grew in size when these older kits became available on the surplus market. The first ARCO Solar panels were equipped with cells 2 to 4 inches (51 to 100 mm ) in diameter. Panels in the 1990s and early 2000s generally incorporated 5-inch (125mm) cells, and since 2008 almost all new panels use 6-inch (150mm) cells. [ 64 ] Also , the widespread introduction of televisions of flat screenThe late 1990s and early 2000s led to a wide availability of large , high-quality glass sheets , which are used on the front of the panels. [ 65 ]
In terms of the cells themselves, there has only been one major change. During the 1990s, polysilicon cells became increasingly popular. [ 64 ] These cells are less efficient than monosilicon cells , but are grown in large vats that greatly reduce the cost of production. [ 64 ] In the mid-2000s, polysilicon dominated the low-cost panel market. [ 64 ]
Applications of photovoltaic solar energy
The large-scale industrial production of photovoltaic panels took off in the 1980s, and its many uses include:
Telecommunications and signaling
Photovoltaic solar energy is ideal for telecommunications applications, including those found for example local stations telephony , antennas of Radio and Television , relay stations microwaves and other electronic communication links. This is because, in most telecommunications applications, storage batteries are used and the electrical installation is normally carried out in direct current.(DC). On hilly and mountainous terrain, radio and television signals can be interfered with or reflected due to rolling terrain. In these locations, low power transmitters (LPT) are installed to receive and relay the signal among the local population. [ 66 ]
Photovoltaic cells are also used to power emergency communication systems , for example in SOS (Emergency Telephone) poles on roads, railway signaling , beacons for aeronautical protection , meteorological stations or monitoring systems for environmental data and air quality. water . [ 61 ]
The reduction in the energy consumption of integrated circuits, made possible in the late 1970s the use of solar cells as a source of electricity in calculators , such as the Royal Solar 1 , Sharp EL-8026 or Teal Photon . [ 67 ]
Also other fixed devices that use photovoltaic energy have seen their use increase in recent decades, in places where the cost of connecting to the electricity grid or the use of disposable batteries is prohibitively expensive. These applications include for example sunlamps, solar lamps , water pumps, parking meters , [ 68 ] [ 69 ] emergency telephones, trash compactors, [ 70 ] signals temporary or permanent traffic loading stations [ 71 ] [ 72 ] or remote monitoring systems.
In isolated environments, where little electrical power is required and access to the grid is difficult, photovoltaic panels have been used as an economically viable alternative for decades. To understand the importance of this possibility, it should be borne in mind that approximately a quarter of the world's population still does not have access to electricity. [ 73 ]
In developing countries, many towns are located in remote areas, several kilometers from the nearest power grid. Because of this, photovoltaic energy is increasingly being incorporated to provide electricity to homes or medical facilities in rural areas. For example, in remote parts of India a rural lighting program has provided lighting using solar-powered LED lamps to replace kerosene lamps. The price of the solar lamps was approximately the same as the cost of supplying kerosene for a few months. [ 74 ] Cubaand other Latin American countries are working to provide photovoltaic energy in areas far from the conventional electricity supply. [ 75 ] These are areas where the social and economic benefits for the local population offer an excellent reason to install photovoltaic panels, although these types of initiatives have typically been relegated to one-off humanitarian efforts. [ 76 ]
Photovoltaic pumping systems (as well as those powered by wind energy ) are very useful where it is not possible to access the general electricity network or it is prohibitively expensive. [ 79 ] Their cost is generally cheaper due to their lower operating and maintenance costs, and they present a lower environmental impact than pumping systems powered by internal combustion engines , which also have lower reliability. [ 80 ] [ 81 ]
The pumps used can be both alternating current (AC) and direct current (DC). Direct current motors are normally used for small and medium-sized applications of up to 3 kW of power, while for larger applications alternating current motors are used coupled to an inverter that transforms the direct current from the photovoltaic panels for use. This allows sizing systems from 0.15 kW to more than 55 kW of power, which can be used to supply complex irrigation or water storage systems. [ 82 ] [ 83 ]
Solar-diesel hybrid systems
Due to the decrease in costs of photovoltaic solar energy, the use of hybrid solar-diesel systems is also spreading, which combine this energy with diesel generators to produce electricity in a continuous and stable way. [ 84 ] This type of installation is normally equipped with auxiliary equipment, such as batteries and special control systems to achieve the stability of the electrical supply of the system at all times. [ 85 ]
Due to its economic viability (the transport of diesel to the point of consumption is usually expensive) in many cases, old generators are replaced by photovoltaics, while new hybrid installations are designed in such a way that they allow the use of the solar resource whenever it is available. minimizing the use of generators, thus reducing the environmental impact of electricity generation in remote communities and in facilities that are not connected to the electricity grid. An example of this are the companies mining , [ 84 ] [ 86 ]Whose farms are normally in open fields, far from large population centers. In these cases, the combined use of photovoltaics makes it possible to greatly reduce dependence on diesel fuel, allowing savings of up to 70% in the cost of energy. [ 87 ]
Although photovoltaics is not yet widely used to provide traction in transportation, it is increasingly being used to provide auxiliary power in ships and cars . Some vehicles are equipped with air conditioning powered by photovoltaic panels to limit the interior temperature on hot days, [ 89 ] while other hybrid prototypes use them to recharge their batteries without the need to connect to the electricity grid. [ 90 ] [ 91 ]Has amply demonstrated the practical ability to design and manufacture solar - powered vehicles and vessels [ 92 ] [ 93 ] and aircraft, [ 94 ] being considered the most viable road transport for photovoltaics. [ 95 ]
The Solar Impulse is a project dedicated to the development of an airplane powered solely by photovoltaic solar energy. The prototype can fly during the day powered by the solar cells that cover its wings, while also charging the batteries that allow it to stay aloft at night. [ 96 ] [ 97 ]
Solar energy is also used routinely in lighthouses, buoys and beacons of maritime navigation , recreational vehicles, charging systems for electric accumulators of ships , systems and cathodic protection . [ 61 ] The recharging of electric vehicles is becoming increasingly important. [ 95 ]
Photovoltaic integrated in buildings
Many photovoltaic installations are often located in buildings: they are usually located on an existing roof, or they are integrated into elements of the building structure itself, such as skylights, skylights or facades. [ 98 ]
Alternatively, a photovoltaic system can also be located physically separate from the building, but connected to the electrical installation of the building to supply energy. In 2010, more than 80% of the 9000 MW of photovoltaic that Germany had in operation at that time, had been installed on roofs. [ 99 ]
Building Integrated Photovoltaics ( BIPV ) is increasingly being incorporated as a primary or secondary source of electrical energy in new domestic and industrial buildings, [ 100 ] and even in other architectural elements, such as bridges. [ 101 ] Roof tiles with integrated photovoltaic cells are also quite common in this type of integration.
According to a study published in 2011, the use of thermal imaging has shown that solar panels, as long as there is an open gap through which air can circulate between the panels and the roof, provide a passive cooling effect in buildings during the day and also help to maintain the heat accumulated during the night. [ 102 ]
Grid connection photovoltaic
One of the main applications of photovoltaic solar energy more developed in recent years, consists of power plants connected to the grid for electricity supply, [ 103 ] as well as photovoltaic self - consumption systems , of generally lower power, but also connected to the power grid.
Although solar panels are usually installed on land, it is possible to install them floating on the waters of reservoirs or calm lakes. [ 104 ] Although it is more expensive, it has many advantages: it reduces the losses due to evaporation of the dammed water, improves its quality (because less algae grows) [ 105 ] , the installation is simpler, it facilitates the cooling of the panels themselves (thereby increasing the energy they produce) [ 104 ] and represents an alternative way for hydroelectric reservoirs to generate electricity, without wasting the water they store or occupying additional land. [ 105 ]
Components of a photovoltaic solar plant
A photovoltaic solar plant has different elements that allow its operation, such as photovoltaic panels for capturing solar radiation, and inverters for transforming direct current into alternating current . [ 106 ] There are others, the most important of which are mentioned below:
Photovoltaic solar panels
Generally, a photovoltaic module or panel consists of an association of cells, encapsulated in two layers of EVA (ethylene-vinyl-acetate), between a front sheet of glass and a back layer of a thermoplastic polymer (frequently used tedlar) or another glass sheet when you want to obtain modules with some degree of transparency. [ 107 ] Very frequently this set is framed in an anodized aluminum structure with the aim of increasing the mechanical resistance of the set and facilitating the anchoring of the module to the support structures. [ 107 ]
The cells most commonly used in photovoltaic panels are silicon, and it can be divided into three subcategories:
- The monocrystalline silicon cells are formed of a single crystal silicon, typically manufactured by the Czochralski process . [ 108 ] This cell type has a uniform dark blue color.
- The polycrystalline silicon cells (also called multicrystalline) are constituted by a set of silicon crystals, which explains their performance is somewhat lower than that of monocrystalline cells. [ 64 ] They are characterized by a more intense blue color.
- The amorphous silicon cells . They are less efficient than crystalline silicon cells but also less expensive. This type of cell is, for example, the one used in solar applications such as watches or calculators . [ 109 ]
The electric current continues to provide the photovoltaic modules can be converted into alternating current using an electronic device called inverter [ 106 ] and inject into the grid (for selling power) or in the internal network (for consumption ).
The simplified process would be as follows:
- The energy is generated at low voltages (380-800 V) and in direct current.
- It is transformed with an inverter in alternating current.
- In plants with a power lower than 100 kW, the energy is injected directly into the distribution network in low voltage (400 V in three-phase or 230 V in single-phase).
- And for powers greater than 100 kW, a transformer is used to raise the energy to medium voltage (up to 36 kV) and it is injected into the transmission networks for its subsequent supply.
In the initial stages of the development of photovoltaic inverters, the requirements of the operators of the electrical networks to which they were connected requested only the contribution of active energy and the disconnection of the inverter from the network if it exceeded certain voltage limits and frequency. With the progressive development of this equipment and the increasing importance of smart electrical grids , inverters are now capable of providing reactive energy and even providing stability to the electrical network. [ 110 ] [ 111 ]
The use of one or two-axis trackers allows a considerable increase in solar production, around 30% for the former and an additional 6% for the latter, in places with high direct radiation. [ 112 ] [ 113 ]
Solar trackers are quite common in photovoltaic applications. [ 114 ] There are several types:
- On two axes: the surface is always perpendicular to the Sun.
- On a polar axis: the surface rotates on an axis oriented south and inclined by an angle equal to latitude. The rotation is adjusted so that the normal to the surface coincides at all times with the terrestrial meridian that contains the Sun.
- On an azimuth axis: the surface rotates on a vertical axis, the angle of the surface is constant and equal to the latitude. The rotation is adjusted so that the normal to the surface coincides at all times with the local meridian that contains the Sun.
- On a horizontal axis: the surface rotates on a horizontal axis and oriented in a north-south direction. The rotation is adjusted so that the normal to the surface coincides at all times with the terrestrial meridian that contains the Sun.
It is the element that transports electrical energy from its generation, for its subsequent distribution and transport. Its sizing is determined by the most restrictive criterion between the maximum allowable voltage drop and the maximum allowable intensity . Increasing the conductor cross-sections that are obtained as a result of theoretical calculations provides added benefits such as:
- More discharged lines, which prolongs the life of the cables.
- Possibility of increasing the power of the plant without changing the conductor.
- Better response to possible short circuits .
- Improvement of the performance ratio (PR) of the installation.
Photovoltaic concentration plants
Another type of technology in photovoltaic plants are those that use a concentration technology called CPV for its acronym in English ( Concentrated Photovoltaics ) [ 115 ] to maximize the solar energy received by the installation, as in a solar thermal power plant . The photovoltaic concentration installations are located in locations with high direct solar irradiation, such as the countries on both shores of the Mediterranean , Australia , the United States , China , South Africa , Mexico, etc. Until 2006 these technologies were part of the research field, but in recent years larger facilities such as ISFOC (Institute of Concentration Photovoltaic Solar Systems) have been put into operation in Puertollano ( Castilla-La Mancha ) with 3 MW supplying electricity to the electricity grid. [ 116 ] [ 117 ] [ 118 ]
The basic idea of the photovoltaic concentration is the substitution of semiconductor material by reflective or refractive material (cheaper). The degree of concentration can reach a factor of 1000, [ 115 ] in such a way that, given the small surface of the solar cell used, the most efficient technology can be used (triple junction, for example). On the other hand, the optical system introduces a loss factor that makes it recover less radiation than flat photovoltaic. This, together with the high precision of the monitoring systems, constitutes the main barrier to be solved by the concentration technology.
The development of large plants (above 1 MW) has recently been announced. [ 119 ] Concentrating photovoltaic plants use a dual axis tracker to allow maximum use of the solar resource throughout the day.
The development of photovoltaic solar energy in the world
Between 2001 and 2016 there has been an exponential growth in photovoltaic production, doubling approximately every two years. [ 120 ] The total photovoltaic power installed in the world (connected to the grid) amounted to 16 gigawatts (GW) in 2008, 40 GW in 2010, 100 GW in 2012, 180 GW in 2014, 300 GW in 2016 and 500 GW in 2018. [ 121 ] [ 122 ] [ 123 ] [ 124 ] [ 125 ] [ 10 ] [ 9 ]
|Potencia fotovoltaica mundial instalada hasta 2018, en gigavatios (GW), expresada por región. |
Europa Asia-Pacífico América del norte y sur China África y Oriente MedioResto del mundo
Historically, the United States led the installation of photovoltaic energy from its inception until 1996, when its installed capacity reached 77 MW, more than any other country to date. In subsequent years, they were overtaken by Japan , which held the lead until Germany surpassed it in 2005, holding the lead ever since. At the beginning of 2016, Germany was approaching 40 GW installed. [ 128 ] However, at that time China , one of the countries where photovoltaics is experiencing the fastest growth, surpassed Germany, becoming the largest producer of photovoltaic energy in the world since then. [128 ] is expected to multiply your current installed capacity to 200 GW by 2020. [ 126 ] [ 129 ] [ 130 ]
The total installed capacity already represents a significant fraction of the electricity mix in the European Union , covering an average of 3.5% of electricity demand and reaching 7% in the periods of greatest production. [ 125 ] In some countries, such as Germany , [ 131 ] [ 132 ] Italy , [ 133 ] [ 134 ] [ 135 ] [ Note 5 ] UK [ 136 ] orSpain , [ 137 ] reaches maximums above 10%, as in Japan [ 138 ] or in some sunny states of the United States , such as California . [ 139 ] The annual production of electrical energy generated by this energy source worldwide was equivalent in 2015 to about 184 TWh , enough to supply the energy needs of millions of homes and covering approximately 1% of the world's electricity demand . [ 125 ]
|Total PV installed capacity in China (in GW) since 2007.|
Photovoltaic energy has become one of the largest industries in the People's Republic of China . The Asian country is the world leader in photovoltaic capacity, with an installed power at the beginning of 2019 of more than 170 GW. [ 140 ] It also has some 400 photovoltaic companies, including Trina Solar , Jinko Solar and JA Solar , world giants in the manufacture of solar panels.. In 2014, it produced approximately half of the photovoltaic products manufactured in the world (China and Taiwan together have more than 60% share). The production of photovoltaic cells and panels in China has increased notably over the last decade: in 2001 it held a share of less than 1% of the world market, while at the same time, Japan and the United States accounted for more than 70% of the World production. However, the trend has been reversed and today China far exceeds the rest of the producers.
Chinese solar panel production capacity practically quadrupled between 2009 and 2011, even exceeding global demand. As a result, the European Union accused the Chinese industry of dumping , that is, selling its panels at prices below cost, imposing tariffs on the import of this material. [ 141 ] [ 142 ]
The installation of photovoltaic energy has developed spectacularly in the Asian country in recent years, even exceeding initial forecasts. Due to such rapid growth, the Chinese authorities have been forced to re-evaluate their PV power target on several occasions.
The total installed power in China grew to 77 GW at the end of 2016, after connecting 36 GW in the last year, according to the country's official statistics. [ 143 ] By 2017, China had exceeded the government's 2020 target of 100 GW photovoltaic power. [ 144 ] For this reason, at the end of 2018 it was announced that China could raise its solar target for 2020 to more than 200 GW. [ 145 ]
This growth reflects the steep decline in the cost of photovoltaic energy, which is now becoming a cheaper option than other energy sources, both at retail and commercial prices. Chinese government sources have stated that photovoltaics will present more competitive prices than coal and gas (also providing greater energy independence) by the end of this decade. [ 146 ]
The United States has been one of the most active countries in the photovoltaic market since 2010, with large companies in the sector, such as First Solar or SolarCity , as well as numerous grid connection plants. At the beginning of 2017, the United States exceeded 40 GW of installed photovoltaic power, [ 147 ] enough to provide electricity to more than 8 million homes, after doubling its solar capacity in less than two years. [ 148 ]
Although the United States does not maintain a uniform national energy policy across the country when it comes to photovoltaics, many states have individually set renewable energy targets , including solar energy in different proportions in this planning. In this regard, California Governor Jerry Brown has signed legislation requiring that 33% of the state's electricity be generated by renewable energy by the end of 2020. [ 149 ]These measures have been supported from the federal government with the adoption of the Investment Tax Credit (ITC), a tax exemption established in 2006 to promote the development of photovoltaic projects, and has recently been extended until 2023. [ 150 ]
A private report [ 151 ] states that photovoltaic solar energy has expanded rapidly during the last 8 years, growing at an average of 40% each year. Thanks to this trend, the cost of the kWh produced by photovoltaic energy has been greatly reduced, while the cost of electricity generated by fossil fuels has not stopped increasing. As a result, the report concludes that PV will reach grid paritycompared to conventional energy sources in many regions of the United States in 2015. But to reach a 10% share of the energy market, the report continues, photovoltaic companies will need to further streamline installations, so that solar energy is become a plug-and-play technology . That is, it is easy to acquire the components of each system and its interconnection is simple, as well as its connection to the network. [ 151 ]
Currently, most of the facilities are connected to the grid and use net balance systems that allow the consumption of nighttime electricity from energy generated during the day. New Jersey leads the states with the least restrictive net balance law, [ 152 ] while California leads the total number of solar-powered homes. Many of them were installed during the million solar roof initiative . [ 153 ]
The current trend and pace of growth indicate that in the coming years a large number of photovoltaic plants will be built in the south and southwest of the country, where the available land is abundant, in the sunny deserts of California, Nevada and Arizona . Companies are increasingly acquiring large surfaces in these areas, with the intention of building larger plants on a large scale. [ 154 ]
Photovoltaic energy in Japan has been expanding rapidly since the 1990s. The country is one of the leaders in the manufacture of photovoltaic modules and ranks among the top in terms of installed power, with more than 23 GW at the end of 2014, most of it connected to the network. [ 155 ] [ 156 ] [ 157 ] Irradiation in Japan is optimal, at between 4.3 and 4.8 kWh · m² · day, making it an ideal country for the development of this type of energy.
The sale of photovoltaic modules for commercial projects has grown rapidly following the introduction by the Japanese government in July 2012 of a tariff for the incentive of photovoltaics following the Fukushima nuclear accident and the stoppage of most of the nuclear power plants that it has. the country.
Most of the modules come from local manufacturers, including Kyocera , Sharp Corporation , Mitsubishi or Sanyo , while a small part is imported, according to data from the Japan Photovoltaic Energy Association (JPA). ). [ 158 ] Traditionally, the photovoltaic market has been highly displaced to the residential segment, accounting for up to 97% of the installed capacity throughout the country until 2012. [ 159 ]Although this trend is reversing, still more than 75% of the cells and modules sold in Japan in early 2012 were destined for residential projects, while about 9% were used in commercial photovoltaic installations. [ 160 ]
In 2014, the total photovoltaic power installed in the country was around 23 GW, which contributed approximately 2.5% to the country's electricity demand. [ 125 ] During the summer of 2015, it was reported that photovoltaic production in Japan had at certain times covered 10% of the total national demand. [ 138 ] Two years later, in 2016, it stands at around 42 GW, [ 147 ] and the forecast is that the Japanese PV market will grow even more in the coming years. [ 161 ]
At the beginning of 2016, Germany had an installed capacity of close to 40 GW. [ 128 ] In 2011 alone, Germany installed about 7.5 GW, [ 162 ] and photovoltaics produced 18 TW · h of electricity, 3% of the total consumed in the country. [ 163 ] [ 132 ]
The photovoltaic market in Germany has grown considerably since the beginning of the 21st century thanks to the creation of a regulated tariff for the production of renewable energy, which was introduced by the " German Renewable Energy Act" , a law published in 2000. Since then, the The cost of photovoltaic installations has fallen by more than 50% in five years, since 2006. [ 164 ] Germany has set a goal of producing 35% of electricity from renewable energy by 2020 and reaching 100% by 2050. [ 165 ]
In 2012, the tariffs introduced cost Germany around 14 billion euros per year, for both wind and solar installations. This cost is distributed among all taxpayers through a surcharge of € 3.6 cents per kWh [ 166 ] (approximately 15% of the total cost of electricity for the domestic consumer). [ 167 ]
The considerable installed power in Germany has set several records in recent years. For two consecutive days in May 2012, for example, the photovoltaic solar plants installed in the country produced 22,000 MWh at noon, which is equivalent to the generating power of twenty nuclear power plants operating at full capacity. [ 168 ] [ note 6 ] Germany pulverized this record on July 21, 2013, with an instantaneous power of 24 GW at noon. [ 169 ] [ 170 ]Due to the highly distributed nature of German PV, approximately 1.3-1.4 million small PV systems contributed to this new brand. Approximately 90% of the solar panels installed in Germany are located on the roof. [ 171 ]
In June 2014, German PV again broke records for several days, producing up to 50.6% of all electricity demand in a single day, and surpassing the previous record for instantaneous power to 24.24 GW . [ 172 ] [ 173 ] [ 174 ]
In early summer 2011, the German government announced that the current regulated tariff scheme would end when installed power reached 52 GW. When this happens, Germany will apply a new injection fee scheme, the details of which are not yet known. [ 175 ]
However, aware that energy storage using batteries is essential for the massive deployment of renewables such as wind energy or photovoltaics, given their intermittency, on May 1, 2013 Germany launched a new aid program to encourage systems photovoltaic with storage batteries. [ 176 ] In this way, photovoltaic installations of less than 30 kW are financedthat install batteries and accumulate electricity, with 660 euros for each kW of battery storage. The program is endowed with 25 million euros per year distributed in 2013 and 2014, and in this way it is possible to have the energy available when the resource is not available —there is no wind or at night—, [ 176 ] in addition to facilitating the stability of the electrical system. [ 177 ]
India is densely populated and also has great solar irradiation, which makes the country one of the best candidates for the development of photovoltaics. In 2009, India announced a program to accelerate the use of solar installations in government buildings, as well as in hospitals and hotels . [ 178 ]
The fall in the price of photovoltaic panels has coincided with an increase in the price of electricity in India. Government support and the abundance of the solar resource have helped drive the adoption of this technology. [ 179 ]
The 345 MW Charanka solar park (one of the largest in the world) was commissioned in April 2012 and expanded in 2015, along with a total of 605 MW in the Gujarat region . [ 180 ] The construction of other large solar parks has been announced in the state of Rajasthan . [ 181 ] Also the solar park Dhirubhai Ambani, 40 MW, was inaugurated in 2012. [ 182 ]
In January 2015, the Indian government increased significantly its solar development plans, setting a target of 100 investments worth 000 million dollars and 100 GW of solar capacity by 2022. [ 183 ] [ 184 ]
At the beginning of 2017, the total installed power in India was above 10 GW. [ 185 ] India hopes to quickly reach 20 GW installed, [ 186 ] fulfilling its goal of creating 1 million jobs [ 187 ] and reach 100 GW in 2022. [ 188 ] [ 189 ]
Italy is among the first countries to produce electricity from photovoltaic energy, thanks to the incentive program called Conto Energia . [ 190 ] Growth has been exponential in recent years: installed power tripled in 2010 and quadrupled in 2011, producing 5.6% of the total energy consumed in the country in 2012. [ 133 ]
This program had a total budget of € 6,700 million, once this limit has been reached, the Government has stopped encouraging new facilities, as network parity has been reached . A report published in 2013 by Deutsche Bank concluded that network parity had indeed been achieved in Italy and other countries around the world. [ 191 ] The sector has managed to provide jobs for around 100,000 people, especially in the field of design and installation of such solar plants. [ 192 ]
New legislation has been in force since mid-2012 that requires the registration of all plants above 12 kW; those of lower power (rooftop photovoltaic in residences) are exempt from registration. [ 193 ] At the end of 2016, the total installed power was above 19 GW , [ 147 ] assuming such significant energy production that several gas plants were operating at half their potential during the day.
Solar power in the UK , although relatively unknown until recently, [ 194 ] has taken off very quickly in recent years, due to the drastic drop in the price of photovoltaic panels and the introduction of regulated tariffs as of April 2010. [ 195 ] In 2014, there were already around 650,000 solar installations in the British Isles, with a total capacity close to 5 GW. [ 196 ] The largest solar plant in the country is located on the Southwick Estate , near Fareham, with a capacity of 48 MW. It was inaugurated in March 2015. [ 197 ]
In 2012, the British government of David Cameron committed to supplying four million homes with solar energy in less than eight years, [ 198 ] which is equivalent to installing some 22 GW of photovoltaic capacity by 2020. [ 195 ] A By early 2016, the UK had installed more than 10 GW of solar PV. [ 199 ]
Between the months of April and September 2016, solar energy produced in the United Kingdom more electricity (6,964 GWh) than that produced by coal (6,342 GWh), both of which represent around 5% of demand. [ 136 ]
The French market is the fourth most important within the European Union , after the markets of Germany, Italy and the United Kingdom. At the end of 2014 it had more than 5 GW installed, and it currently maintains sustained growth, it is estimated that in 2015 it will connect an additional 1 GW to the electricity grid to the current capacity. [ 200 ] Recently, the Gallic country increased the quota of its auctions for photovoltaic energy from 400 to 800 MW, as a consequence of the government's recognition of the increasing competitiveness of solar energy. [ 200 ]
In France there is one of the largest photovoltaic plants in Europe, a 300 MW project called Cestas. [ 201 ] [ 202 ] [ 203 ] Its entry into operation took place in late 2015, providing the photovoltaic industry an example to follow for the rest of European industry. [ 201 ]
Spain is one of the European countries with the highest annual irradiation. [ 43 ] This makes solar energy more profitable in this country than in others. Regions such as the north of Spain, which are generally considered unsuitable for photovoltaic energy, receive more annual irradiation than the average in Germany, a country that has held the leadership in the promotion of photovoltaic solar energy for years. [ 43 ]
Since the early 2000s, in accordance with the support measures for renewable energies that were being carried out in the rest of Europe, the regulation that establishes the technical and administrative conditions had been approved, and that marked the beginning of a slow take-off of photovoltaics in Spain. In 2004, the Spanish government removed economic barriers to connecting renewable energy to the electricity grid. Royal Decree 436/2004 equalized the conditions for its large-scale production, and guaranteed its sale through generation premiums. [ 204 ]
Thanks to this regulation, and the subsequent RD 661/2007, [ 205 ] Spain was in 2008 one of the countries with the most installed photovoltaic power in the world, with 2708 MW installed in a single year. However, subsequent modifications in the sector legislation [ 206 ] slowed down the construction of new photovoltaic plants, in such a way that in 2009 only 19 MW were installed, in 2010, 420 MW, and in 2011 354 MW were installed, corresponding 2% of the total of the European Union . [ 131 ]
In terms of energy production, in 2010 photovoltaic energy covered approximately 2% of electricity generation in Spain, while in 2011 and 2012 it represented 2.9%, and in 2013 3.1% of electricity generation according to operator data, Red Eléctrica . [ 207 ] [ 208 ] [ 209 ] In 2018, the share of photovoltaic solar energy in Spain reached 3.2% of all energy produced nationally. [ 210 ]
At the beginning of 2012 , the Spanish Government approved a Royal Decree Law by which the installation of new photovoltaic plants and other renewable energies was paralyzed . [ 211 ] At the end of 2015, the photovoltaic power installed in Spain amounted to 4,667 MW. [ 212 ] In 2017 , Spain fell for the first time from the list of the ten countries with the highest installed photovoltaic capacity, after being surpassed by Australia and South Korea . [ 213 ]However, in July 2017, the Government organized an auction that awarded more than 3,500 MW of new photovoltaic power plants, [ 214 ] which will allow Spain to achieve the renewable energy generation targets set by the European Union for 2020 As a novelty, neither the construction of the awarded plants nor their operation will entail any cost for the system, except in the event that the market price falls below a land established in the auction. The large drop in the cost of photovoltaic energy has allowed large companies to bid at market prices. [ 215 ]
In 2019, photovoltaics increased the installed power in Spain by more than 3,000 MW with a total installed power of 7,800 MW. [ 216 ] Spain has the largest connected photovoltaic plant in Europe, located in the town of Mula (Murcia), with 494 MW. [ 217 ]
In Latin America , photovoltaics has started to take off in recent years. The construction of a good number of solar plants has been proposed in various countries, throughout the entire region. [ 218 ]
Mexico is the Latin American country with the highest installed capacity, and it still has enormous potential when it comes to solar energy. [ 219 ] [ 220 ] 70% of its territory has a higher irradiation 4.5 kWh / m² / day, which makes it a very sunny country, and implies that using the current photovoltaic technology, solar plant of 25 km² anywhere in the state of Chihuahua or the Sonora desert (which would occupy 0.01% of the surface of Mexico) could provide all the electricity demanded by the country. [ 221 ]
The Aura Solar project , located in La Paz (Baja California Sur) , inaugurated in early 2014, which intended to generate 82 GWh per year, enough to supply the consumption of 164,000 inhabitants (65% of the population of La Paz ), but it was devastated by Hurricane Odile in September of the same year and the plant stopped operating for several months. In 2016 the reconstruction of the plant was carried out, which was completed at the end of the same year and since 2017 to date it is in operation again. [ 222 ]
Another 47 MW photovoltaic plant is in the planning phase in Puerto Libertad (Sonora) . [ 223 ] The plant, originally designed to house 39 MW, was expanded to allow the generation of 107 GWh / year. [ 224 ]
Mexico already has more than 3,000 MW installed. It is expected to experience greater growth in the coming years, in order to reach the goal of covering 35% of its energy demand from renewable energy in 2024, according to a law approved by the Mexican government in 2012. [ 225 ] [ 226 ]
Chile led solar production in Latin America until a few years ago. The first photovoltaic solar plant in Chile was El Águila, 2.2 MWp located in Arica, completed in 2012. This country inaugurated a 100 MW photovoltaic plant in June 2014, which became the largest to date in Latin America. [ 227 ] The high price of electricity and the high levels of radiation that exist in northern Chile have promoted the opening of an important market free of subsidies. [ 228 ]At the end of 2018, the Andean country had 2,427 photovoltaic MW in operation. Chile has a potential of more than 1800 GW of solar energy possible in the Atacama desert, according to a study carried out by the German GIZ in Chile (German International Cooperation Agency, 2014). The Atacama desert is the place with the highest irradiation in the world with global irradiation levels (GHI), above 2700 kWh / m² / year.
Other South American countries have started installing large-scale photovoltaic plants, including Peru . [ 229 ] Brazil instead is experiencing slower growth of the sector, partly due to the high generation by hydropower in the country, [ 230 ] although the state of Minas Gerais leading the effort, after approval by the Brazilian government of a photovoltaic cell and panel factory in that region. [ 231 ] [ 230 ]
The following table shows the detail of the installed world power, broken down by each country, from 2002 to 2019:
|World total||2220||2798||3911||5340||6915||9443||15 772||23 210||39 778||73 745||104 015||139 523||176 089||222 213||296 155||389 411||488 739||587 134||713 970|
|China||-||-||-||-||-||-||-||-||893||3 108||6 719||17 759||28 399||43 549||77 809||130 822||175 287||204 996||254 355|
|USA||212,2||275,2||376||479||624||830,5||1168,5||1255,7||2519||5 644||8 613||13 045||17 651||23 442||34 716||43 115||53 184||60 682||75 572|
|Japan||636,8||859,6||1132||1421,9||1708,5||1918,9||2144||2627||3617||4 890||6 430||12 107||19 334||28 615||38 438||44 226||55 500||61 526||67 000|
|Germany||278||431||1034||1926||2759||3835,5||5340||9959||17 320||25 916||34 077||36 710||37 900||39 224||40 679||42 293||45 158||49 047||53 783|
|India||-||-||-||-||-||-||-||-||189||566||982||1 499||3 673||5 593||9 879||18 152||27 353||35 089||39 211|
|Italy||22||26||30,7||37,5||50||120,2||458,3||1157||3502||13 136||16 790||18 190||18 600||18 907||19 289||19 688||20 114||20 871||21 600|
|Australia||39,1||45,6||52,3||60,6||70,3||82,5||104,5||183,6||504||2 473||3 799||4 568||5 287||5 946||6 689||7 354||8 627||13 252||17 627|
|Vietnam||-||-||-||-||-||-||-||-||-||5||5||5||5||5||5||8||105||4 898||16 504|
|South Korea||5,4||6||8,5||13,5||35,8||81,2||357,5||441,9||662||730||1 024||1 555||2 481||3 615||4 502||5 835||7 130||10 505||14 575|
|Spain||7||12||23||48||145||693||3354||3438||3892||5 432||6 569||6 994||7 001||7 008||7 017||7 027||7 068||11 277||14 089|
|UK||4,1||5,9||8,2||10,9||14,3||18,1||22,5||29,6||72||1 000||1 753||2 937||5 528||9 601||11 914||12 760||13 073||13 346||13 563|
|France||17,2||21,1||26||33||43,9||75,2||179,7||335,2||1025||3 004||4 359||5 277||6 034||7 138||7 702||8 610||9 691||10 804||11 733|
|Netherlands||26,3||45,7||49,2||50,7||52,2||52,8||57,2||67,5||97||149||287||650||1 007||1 526||2 135||2 911||4 608||7 177||10 213|
|Brazil||-||-||-||-||-||-||-||-||2||2||3||8||20||41||148||1 296||2 470||4 615||7 881|
|Ukraine||-||-||-||-||-||-||-||-||3||188||372||748||819||841||955||1 200||2 003||5 936||7 331|
|Turkey||0,9||1,3||1,8||2,3||2,8||3,3||4||5||6||7||12||19||41||250||834||3 422||5 064||5 996||6 668|
|South Africa||-||-||-||-||-||-||-||-||40||6||11||262||1 163||1 352||2 174||3 447||4 801||4 905||5 990|
|Taiwan||-||-||-||-||-||-||-||-||32||130||231||410||636||884||1 245||1 768||2 738||4 150||5 817|
|Belgium||-||-||-||-||-||-||-||574||803||1 979||2 647||2 902||3 015||3 132||3 329||3 621||4 000||4 637||5 646|
|Mexico||16,2||17,1||18,2||18,7||19,7||20,8||21,8||25||31||39||60||82||116||173||389||674||2 555||4 440||5 644|
|Poland||-||-||-||-||-||-||-||-||-||1||1||2||27||108||187||287||562||1 539||3 936|
|Canada||10||11,8||13,9||16,7||20,5||25,8||32,7||94,6||200||497||766||1 210||1 843||2 517||2 661||2 913||3 100||3 310||3 325|
|Greece||-||-||-||-||-||-||-||55||206||612||1 536||2 579||2 596||2 604||2 604||2 606||2 652||2 834||3 247|
|Chile||-||-||-||-||-||-||-||-||-||-||2||15||221||576||1 125||1 809||2 236||2 654||3 205|
|Swiss||19,5||21||23,1||27,1||29,7||36,2||47,9||73,6||111||223||437||756||1 061||1 394||1 664||1 906||2 203||2 589||3 118|
|Thailand||-||-||-||-||-||-||-||-||28||79||382||829||1 304||1 425||2 451||2 702||2 967||2 988||2 988|
|United Arab Emirates||-||-||-||-||-||-||-||-||-||13||13||126||133||134||141||355||598||1 918||2 539|
|Austria||10,3||16,8||21,1||24||25,6||27,7||32,4||52,6||103||174||337||626||785||937||1 096||1 269||1 455||1 702||2 220|
|Czech Republic||-||-||-||-||-||-||-||463,3||1953||1 913||2 022||2 064||2 067||2 075||2 068||2 070||2 075||2 086||2 073|
|Hungary||-||-||-||-||-||-||-||-||-||4||12||35||89||172||235||344||728||1 400||1 953|
|Egypt||-||-||-||-||-||-||-||-||-||35||35||35||35||45||59||180||765||1 662||1 694|
|Israel||-||-||0,9||1||1,3||1,8||3||24,5||66||196||243||426||676||772||872||975||1 076||1 438||1 439|
|Russia||-||-||-||-||-||-||-||-||-||-||-||1||5||61||76||225||535||1 064||1 428|
|Romania||-||-||-||-||-||-||-||-||-||1||41||761||1 293||1 326||1 372||1 374||1 386||1 398||1 387|
|Jordan||-||-||-||-||-||-||-||-||-||-||-||-||-||6||296||406||809||1 101||1 359|
|Denmark||1,6||1,9||2,3||2,7||2,9||3,1||3,3||4,6||7,1||17||402||571||607||782||851||906||998||1 080||1 300|
|Bulgaria||-||-||-||-||-||-||-||5,7||18||154||1 013||1 020||1 026||1 029||1 028||1 036||1 033||1 048||1 073|
Photovoltaic power installed in the world (in GW). Historical data until 2014 and forecast until 2019.|
Historical facts Estimate for 2015 (+55 GW, 233 GW) Moderate forecast 396 GW in 2019 Optimistic forecast 540 GW in 2019Source: SPE , Global Market Outlook 2015, [ 240 ] : 14 along with industry forecasts for 2015. [ Note 7 ]
Installed photovoltaic power is estimated to have grown by around 75 GW in 2016, [ 127 ] and China has taken the lead against Germany, already being the largest producer of photovoltaic energy. By 2019, total power is estimated to reach 396 GW (moderate scenario) or even 540 GW (optimistic scenario) worldwide.
The consulting firm Frost & Sullivan estimates that photovoltaic power will increase to 446 GW by 2020, with China, India and the United States being the countries with the highest growth, while Europe will see its capacity double compared to current levels. [ 241 ] San Francisco-based market analyst and consulting firm Grand View Research published its estimates for the sector in March 2015. The photovoltaic potential of countries such as Brazil , Chile and Saudi Arabiait has not yet developed as expected, and is expected to be developed over the next few years. In addition to this, the increase in manufacturing capacity in China is expected to continue to help drive down declining prices further. The consultant estimates that global PV capacity reaches 490 GW by 2020. [ 242 ]
The PV Market Alliance (PVMA) organization, a consortium made up of several research entities, estimates that global capacity will be between 444-630 GW in 2020. In the most pessimistic scenario, it expects the annual installation rate to be between 40 and 50 gigawatts at the end of the decade, while in the most optimistic scenario, it estimates that between 60 and 90 GW will be installed annually during the next five years. The intermediate stage estimated to be between 50 and 70 GW, to reach 536 GW 2020. [ 243 ] [ 244 ] figures PVMA match those previously published by Solar Power Europe . In June 2015, Greentech Media (GTM) published its Global PV Demand Outlook reportby 2020, which estimates that annual installations will increase from 40 to 135 GW, reaching a total global capacity of almost 700 GW in 2020. GTM's estimate is the most optimistic of all those published to date, estimating that 518 will be installed GW between 2015 and 2020, which is more than double that of other estimates. [ 245 ]
For its part, EPIA also estimates that photovoltaic energy will cover between 10 and 15% of Europe's demand in 2030. A joint report by this organization and Greenpeace published in 2010 shows that by 2030, a total of 1845 GW Photovoltaics could generate approximately 2,646 TWh / year of electricity worldwide. Combined with energy efficiency measures , this figure would represent covering the consumption of almost 10% of the world's population. By 2050, it is estimated that more than 20% of the world's electricity could be covered by photovoltaic energy. [ 246 ]
Grid connection photovoltaic plants
In Europe and the rest of the world, a large number of large-scale photovoltaic plants have been built. [ 103 ] Currently the largest photovoltaic plants in the world are, according to their production capacity: [ 103 ]
|Bhadla Solar Park||India||2245 MW||2020|
|Qinghai Solar Plant||China||2200 MW||2020|
|Pavagada Solar Park||India||2050 MW||2019|
|Tengger Desert Solar Park||China||1547 MW||2016|
|Ben Ban Solar Park||Egypt||1500 MW||2019|
|Noor Abu Dhabi||United Arab Emirates||1177 MW||2019|
|Kurnool Solar||India||1000 MW||2017|
|Datong Solar Power Top Runner Base||China||1000 MW||2016|
|Yanchi Solar PV Station||China||1000 MW||2016|
|Longyangxia Hydro-solar PV Station||China||850 MW||2013-2017|
|Villanueva Solar Park||Mexico||828 MW||2018|
|Rewa Ultra Mega Solar||India||750 MW||2018|
|Charanka Solar Park||India||690 MW||2012-2019|
|Kamuthi Solar Power Project||India||648 MW||2016|
|Mohammed bin Rashid Al Maktoum||United Arab Emirates||613 MW||2019|
|Solar Star||USA||579 MW||2015|
|Copper Mountain Solar Facility||USA||552 MW||2016|
|Desert Sunlight Solar Farm||USA||550 MW||2015|
|Topaz Solar Farm||USA||550 MW||2014|
|Núñez de Balboa Solar Plant||Spain||500 MW||2020|
|Solar Plant From||Spain||494 MW||2019|
The largest solar plants in the world are located in China and India. Kurnool Solar , in the Indian state of Andhra Pradesh is home to 1 GW of capacity, equivalent in power to a nuclear power plant. The Yanchi Solar plant in Qinghai province (China) also has such capacity. Also among the top spots is Longyangxia Hydro-Solar PV Station , located next to the Longyangxia Dam in China. It consists of a hydroelectric macro-complexof 1280 MW, to which a 320 MW photovoltaic plant was subsequently added, completed in 2013. At the end of 2015, a second phase of 530 MW was inaugurated, which raised the total power of the solar plant to 850 MW. [ 247 ] [ 248 ] [ 249 ]
Other large-scale projects are located in the United States. Solar Star , has a power of 579 MW and is located in California. [ 250 ] [ 251 ] Plants Topaz Solar Farm and Desert Sunlight Solar Farm in Riverside County, California also also has a power of 550 MW. [ 252 ] [ 253 ] The project Blythe Solar Power is a 500 MW photovoltaic plant, also located in Riverside County, whose construction is expected soon. [ 254 ]In Europe, the largest plant is located in Murcia (Spain). It has a capacity of 494 MW and started operating in 2019. [ 216 ]
There are many other large-scale plants under construction. The McCoy Solar Energy Project , [ 255 ] [ 256 ] in the United States, will have a capacity of 750 MW when completed. [ 257 ] In recent years, it has been proposed to build several plants with powers greater than 1000 MW in different parts of the world. Quaid-e-Azam Solar Park plant in Pakistan and the first phase is already operational with 100 MW, [ 258 ] [ 259 ] [ 260 ]It plans to expand its capacity to 1,500 MW. [ 261 ] The United Arab Emirates is also planning the construction of a 1000 MW plant. [ 262 ] [ 263 ] [ 264 ] The Ordos Solar Project , [ 265 ] located in China, will reach 2000 MW. [ 266 ] The Westlands Solar Park project has a planned capacity of 2,700 MW, [ 267 ]To be completed in several phases. The Ladakh project in India plans to host 5 GW of photovoltaic capacity. [ 268 ]
With regard to rooftop photovoltaic installations, the largest installation is at the Renault Samsung Motors facilities in Busan ( South Korea ), and has 20 MW distributed over the different roofs, parking lots and infrastructures of the complex. Opened in 2013, it provides power to the factory and thousands of nearby homes. [ 269 ]
Storage of photovoltaic energy using batteries
Energy storage is presented as a major challenge to allow a continuous supply of energy, since solar energy cannot be generated at night. The rechargeable batteries have traditionally been used to store excess electricity in isolated systems. With the emergence of grid-connected systems, excess electricity can be transported through the electricity grid to points of consumption. When renewable energy production accounts for a small fraction of demand, other energy sources can adjust their production appropriately to support variability in renewables, but with the growth of renewables, control becomes necessary. more suitable for network balancing.
With the decline in prices, photovoltaic plants begin to have batteries to control the output power or store excess energy so that it can be used during the hours when renewable plants cannot generate directly. This type of battery allows to stabilize the electrical network by smoothing the demand peaks during minutes or hours. It is anticipated that in the future these batteries will play an important role in the electricity grid, since they can be charged during periods when generation exceeds demand and discharge this energy into the grid when demand is greater than generation.
For example, in Puerto Rico a system with a capacity of 20 megawatts for 15 minutes (5 megawatt hours) is used to stabilize the frequency of the grid on the island. Another system of 27 megawatts for 15 minutes (6,75 MWh) with nickel-cadmium was installed in Fairbanks ( Alaska ) in 2003 to stabilize the voltage transmission lines. [ 270 ]
Most of these battery banks are located next to the photovoltaic plants themselves. The largest systems in the United States include the 31.5 MW battery at the Grand Ridge Power plant in Illinois, and the 31.5 MW battery at Beech Ridge, Virginia. [ 271 ] Among the most prominent projects are the 400 MWh system (100 MW for four hours) of the Southern California Edison project and a 52 MWh project in Kauai ( Hawaii ), which allows to completely displace the production of a plant 13MW for use after sunset. [ 272 ] Other projects are located in Fairbanks (40 MW for 7 minutes using nickel-cadmium batteries) [273 ] and in Notrees ( Texas ) (36 MW for 40 minutes using lead-acid batteries). [ 274 ]
In 2015, a total of 221 MW was installed with battery storage in the United States, and it is estimated that the total power of this type of system will grow to 1.7 GW in 2020. Most of it installed by the market's own wholesale companies American. [ 275 ]
Self-consumption and net balance
Photovoltaic self-consumption consists of the individual small-scale production of electricity for one's own consumption, through photovoltaic panels. This can be complemented with the net balance . This production scheme, which makes it possible to compensate for electricity consumption through what is generated by a photovoltaic installation at times of lower consumption, has already been successfully implemented in many countries. It was proposed in Spain by the Photovoltaic Industry Association (ASIF) to promote renewable electricity without the need for additional financial support, [ 276 ] and was in the project phase by the IDAE . [ 277 ] It was later collected in theRenewable Energy Plan 2011-2020, [ 278 ] but it has not yet been regulated.
However, in recent years, due to the growing boom in small renewable energy facilities, self-consumption with a net balance has begun to be regulated in various countries of the world, being a reality in countries such as Germany, Italy, Denmark, Japan, Australia , United States, Canada and Mexico, among others.
Among the advantages of self-consumption compared to the consumption of the network are the following:
- With self-consumption systems becoming cheaper and electricity rates rising, it is becoming more profitable for you to produce your own electricity yourself. [ 17 ]
- Dependence on electricity companies is reduced.
- Photovoltaic self-consumption systems use solar energy, a free source, inexhaustible, clean and respectful with the environment.
- A distributed electricity generation system is generated that reduces the need to invest in new networks and reduces energy losses due to the transport of electricity through the network. [ 279 ]
- The energy dependence of the country with the outside is reduced.
- Problems to supply all the demand at rush hour, known for power cuts and power surges, are avoided.
- The impact of electrical installations on your environment is minimized.
- Companies reduce their energy costs, improve their image and reinforce their commitment to the environment. [ 280 ]
In the case of photovoltaic self - consumption , the return on investment time is calculated on the basis of how much electricity is no longer consumed from the grid, due to the use of photovoltaic panels.
For example, in Germany, with electricity prices of € 0.25 / kWh and insolation of 900 kWh / kWp, a 1 kWp installation saves about € 225 per year, which with installation costs of € 1,700 / kWp means that the system will pay for itself in less than 7 years. [ 281 ] This figure is even lower in countries like Spain, with irradiation higher than that existing in the north of the European continent. [ 43 ]
Efficiency and costs
The effect of temperature on photovoltaic modules is usually quantified by means of coefficients that relate variations in open circuit voltage, short circuit current and maximum power to changes in temperature. In this article, experimental guidelines integral to estimate the temperature coefficients [ 282 ]
The efficiencies of solar cells range from 6% of those based on amorphous silicon to 46% of multi-junction cells . [ 284 ] [ 285 ] The conversion efficiencies of the solar cells used in commercial photovoltaic modules (monocrystalline or polycrystalline silicon) are around 16-22%. [ 286 ] [ 287 ]
The cost of solar cells, crystalline silicon has dropped from $ 76.67 / Wp $ 1977 to about 0.36 / Wp in 2014. [ 288 ] [ 283 ] This trend is called Swanson's Law , a prediction similar to the well-known Moore's Law , which states that the prices of solar modules fall by 20% each time the capacity of the photovoltaic industry is doubled. [ 289 ]
In 2014, the price of solar modules had been reduced by 80% from the summer 2008, [ 290 ] [ 291 ] placing solar power first in an advantageous position with respect to the price of electricity paid for the consumer in a good number of sunny regions. [ 292 ] In this sense, the average cost of electricity generation of photovoltaic solar energy is already competitive with that of conventional energy sources in a growing list of countries, [ 293 ] particularly when considering the generation time of said energy, since electricity is usually more expensive during the day. [294 ] There has been stiff competition in the production chain, and further falls in the cost of photovoltaic energy are expected in the coming years, posing a growing threat to the dominance of generation sources based on fossil fuels. . [ 295 ] As time passes, renewable generation technologies are generally cheaper, [ 296 ] [ 297 ] while fossil fuels become more expensive:
The lower the cost of photovoltaic solar energy falls, the more favorably it competes with conventional energy sources, and the more attractive it is to electricity users around the world. Small-scale PV can be used in California at prices $ 100 / MWh ($ 0.10 / kWh) below most other types of generation, even those that run on low-cost natural gas . Lower costs in photovoltaic modules also stimulate the demand of private consumers, for whom the cost of photovoltaics already compares favorably to the final prices of conventional electrical energy. [ 298 ]
For large-scale installations, prices have already been reached below $ 1 / watt. For example, in April 2012 a price for photovoltaic modules was published at € 0.60 / Watt ($ 0.78 / Watt) in a 5-year framework agreement. [ 301 ] In some regions, photovoltaic energy has reached grid parity, which is defined when the costs of photovoltaic production are at the same level, or below, of the electricity prices paid by the final consumer (although in most cases still above the generation costs in the power plants coal or gas, excluding distribution and other induced costs). Photovoltaic energy is generated during a period of the day very close to peak demand (it precedes it) in electrical systems that make great use of air conditioning. More generally, it is clear that with a coal price of $ 50 / ton, which raises the price of coal plants to 5 cents / kWh, PV will be competitive in most countries. The falling price of photovoltaic modules has been quickly reflected in a growing number of installations, accumulating in all of 2011 about 23 GW installed that year. Although some consolidation is expected in 2012, due to cuts in economic support in the important markets of Germany and Italy, the strong growth will most likely continue for the rest of the decade. In fact, a study already mentioned that total investment in renewable energy in 2011 had exceeded investments in coal-based power generation.
The trend is for prices to decline further over time once PV components have entered a clear and straightforward industrial phase. [ 302 ] [ 303 ] At the end of 2012, the average price of photovoltaic modules had dropped to $ 0.50 / Wp, and forecasts suggest that the price will continue to fall to $ 0.36 / Wp in 2017. [ 304 ]
In 2015, the German Fraunhofer Institute for Solar Energy (ISE) conducted a study that concluded that most of the scenarios envisaged for the development of solar energy underestimate the importance of photovoltaics. [ 305 ] The study carried out by the Fraunhofer institute estimated that the levelized cost (LCOE) of photovoltaic solar energy for grid connection plants will in the long term be between € 0.02 and € 0.04 / kWh, levels below those of conventional energy sources. [ 306 ]
Excerpt from the conclusions of the study by Fraunhofer ISE: Current and Future Cost of Photovoltaics. Long-term Scenarios for Market Development, System Prices and LCOE of Utility-Scale PV Systems. Long-term Scenarios for Market Development, Pricing Systems and LCOE of Grid-Connected Photovoltaic Systems ) - February 2015 : [ 306 ]
- Photovoltaic solar energy is already a low-cost renewable generation technology today. The cost of large-scale photovoltaic plants connected to the grid fell in Germany from values above € 0.40 / kWh in 2005 to € 0.09 / kWh in 2014. Even lower costs have been published in other sunnier regions of the rest of the world, given that a good part of the components of photovoltaic plants are sold in global markets.
- Solar energy will soon become the cheapest source of energy in many regions of the world. Even assuming conservative projections and considering that there will be no major technological advances, a halt in the cost reduction that is currently taking place is not expected. Depending on the annual irradiation of the chosen site, the cost of photovoltaics will be between € 0.04-0.06 / kWh by 2025, reaching € 0.02-0.04 / kWh before 2050 (conservative estimate).
- The financial and regulatory environment will be the key to future cost reductions for this technology. The cost of components in global markets will decrease regardless of local conditions in each country. But inadequate regulation can lead to a cost increase of up to 50% due to the higher cost of financing. This can even negatively offset the fact of having a greater solar resource in some areas.
- Most of the scenarios envisaged for the development of solar energy underestimate the importance of photovoltaics. Based on outdated cost estimates, most projections for the future of domestic, regional and global energy systems foresee only a small production of solar energy. The results of our analysis indicate that a fundamental review of this aspect is necessary to achieve cost optimization.
Thin film or thin film photovoltaic energy
Another low cost alternative to crystalline silicon cells is thin film or film photovoltaic power which is based on third generation solar cells. [ 308 ] They consist of a solar cell that is manufactured by depositing one or more thin layers (thin film ) of photovoltaic material on a substrate.
Thin film solar cells are usually classified according to the photovoltaic material used:
- Amorphous silicon (a-Si) and other thin film silicon (TF-Si) [ 309 ]
- Cadmium telluride (CdTe) [ 310 ]
- Copper indium gallium selenide (CIS or CIGS) [ 311 ]
- Dye-sensitized solar cells (DSC) [ 312 ] and other organic solar cells. [ 313 ]
The Low Cost Solar Energy International Conference in Seville , held in February 2009, was the first showcase in Spain of these. [ 314 ] This technology caused great expectations in its early days. However, the sharp drop in the price of polycrystalline silicon cells and modules since late 2011 has caused some thin-film manufacturers to exit the market, while others have seen their profits greatly reduced. [ 315 ]
The amount of solar energy reaching the earth's surface is enormous, about 122 petawatts (PW), and is equivalent to almost 10,000 times more than the 13 TW consumed by humanity in 2005. [ 316 ] This abundance suggests that it is not It will be a long time before solar energy becomes the main source of energy for mankind. [ 317 ] Additionally, photovoltaic electricity generation has the highest energy density (a global average of 170 W / m²) of all renewable energies. [ 316 ]
Unlike power generation technologies based on fossil fuels , photovoltaic solar energy does not produce any harmful emissions during its operation, [ 1 ] although the production of photovoltaic panels also has a certain environmental impact . The final waste generated during the production phase of the components, as well as the emissions from the factories, can be managed through existing pollution controls. In recent years, recycling technologies have also been developed to manage the different photovoltaic elements at the end of their useful life, [ 318 ]And programs are being carried out to increase recycling among photovoltaic producers. [ 319 ]
The energy return rate of this technology, meanwhile, is increasing. With current technology, photovoltaic panels recover the energy necessary for their manufacture in a period between 6 months and 1 year and a half; taking into account that their average useful life is more than 30 years, they produce clean electricity for more than 95% of their life cycle. [ 320 ]
Emissions of greenhouse gases
Emissions greenhouse gases throughout the life cycle for photovoltaics are close to 46 g / kWh and can be reduced even to 15 g / kWh in the near future. [ 321 ] In comparison, a combined cycle gas plant emits between 400-599 g / kWh, [ 322 ] a diesel plant 893 g / kWh, [ 322 ] a coal plant 915-994 g / kWh [ 323 ] or with carbon capture technology about 200 g / kWh (excluding emissions during coal mining and transportation), and a geothermal power planthigh temperature, between 91-122 g / kWh. [ 322 ] The emission intensity for the lifecycle of hydropower , wind and nuclear energy is less than that of photovoltaics, according to data published by the IPCC in 2011. [ 322 ]
Like all energy sources whose emissions depend primarily on the construction and transportation phases, the transition to a low-carbon economy could further reduce carbon dioxide emissions during the manufacture of solar devices.
A photovoltaic system of 1 kW of power saves the combustion of approximately 77 kg (170 pounds) of carbon, avoids the emission into the atmosphere of about 136 kg (300 pounds) of carbon dioxide, and saves monthly the use of about 400 liters (105 gallons) of water. [ 324 ]
Recycling of photovoltaic modules
A photovoltaic installation can operate for 30 years or more [ 325 ] with little maintenance or intervention after commissioning, so after the initial investment cost required to build a photovoltaic installation, its operating costs are very low in comparison with the rest of existing energy sources. At the end of their useful life, most of the photovoltaic panels can be treated. Thanks to technological innovations that have been developed in recent years, it is possible to recover up to 95% of certain semiconductor materials and glass, as well as large amounts of ferrous and non-ferrous metals used in the modules. [ 326 ] Some private companies [327 ] and non-profit organizations, such as PV CYCLE in the European Union, are working on collecting and recycling panels at the end of their useful life. [ 328 ]
Two of the most common recycling solutions are:
- Silicon panels: Aluminum frames and junction boxes are manually dismantled at the beginning of the process. The panel is crushed and the different fractions are separated: glass, plastics and metals. [ 329 ] More than 80% of the incoming weight can be recovered [ 330 ] and, for example, mined mixed glass is readily accepted by the foam glass and insulation industries. This process can be carried out by flat glass recyclers, since the morphology and composition of a photovoltaic panel is similar to the flat glass used in the construction and automobile industries.
- Panels made of other materials: Today there are specific technologies for recycling photovoltaic panels that do not contain silicon, some techniques use chemical baths to separate the different semiconductor materials. [ 331 ] For cadmium tellurium panels , the recycling process begins by crushing the module and subsequently separating the different parts. This recycling process is designed to recover up to 90% of glass and 95% of semiconductor materials. [ 332 ] In recent years, some private companies have set up recycling facilities on a commercial scale. [ 333 ]
Since 2010 an annual conference has been held in Europe that brings together producers, recyclers and researchers to discuss the future of photovoltaic module recycling. In 2012 it took place in Madrid . [ 334 ] [ 335 ]
- Net balance
- Photoelectric cell
- Thin film solar cell
- solar thermal plant
- International committees for the normalization of photovoltaic solar energy
- Photoelectric effect
- Renewable electricity
- Renewable energies in the European Union
- Solar energy in Spain
- Thermal solar energy
- Photovoltaic integrated in buildings
- Solar garden
- Solar Energy Institute at the Polytechnic University of Madrid
- Spanish electricity market
- Photovoltaic panel
- Smart grid
- Physicist Alejandro Volta also provides the term volt to the unit of measure for the potential difference in the International System of Measurements.
- A small proportion of silicon atoms is replaced by an element of higher valence in the periodic table , that is, it has more electrons in its valence shell than silicon. Silicon has 4 electrons in its valence shell: elements from column 15 can be used , for example phosphorus .
- By an element of valence less than silicon. It can be boron (B) or another element from column 13 .
- However, it can be given a wavy shape, to increase the active surface.
- Photovoltaics supplied 8.4% of electricity demand in Italy in August 2012. The Italian grid operator Terna SpA reported that, in August 2012, 8.4% of the country's electricity demand it was supplied with electricity produced by photovoltaic systems. Terna's monthly reports on the country's electricity system showed that the power generated by photovoltaic sources increased from 1,501 gigawatt hours generated in August 2011 to 2,240 gigawatt hours reached in August 2012, representing an increase of 49.2 %. Source: Terna SpA
- And these figures continue to grow: due to the increase in the photovoltaic power installed in the country, from January to September 2012 6.1% of the German electricity demand was covered with energy produced by photovoltaic systems, according to the German Association of the energy and water industries (BDEW).
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