Efficiency of solar panels. The whole truth about the efficiency of solar panels (10 photos)

Solar panels are a unique system that allows you to convert solar rays into electrical and thermal energy. The growing demand for solar products today is determined by their quick payback, durability, and availability of coolant. But what voltage can solar panels produce? Read the article about how effective solar systems are and what their efficiency depends on.

High efficiency solar panels: types of converters

The efficiency of solar batteries is a value that is equal to the ratio of the power of electricity to the power of solar rays incident on the panel of the device. Modern solar cells have an efficiency ranging from 10 to 45%. This large difference is due to differences between the materials used and the design of the battery plates.

So, solar panel plates can be:

• Thin film;
• Multi-junction.

The latter type of solar panels, today, are the most expensive, but also the most productive. This is due to the fact that each junction in the plate absorbs waves of a certain length. Thus, the device covers the entire spectrum of sunlight. The maximum efficiency of batteries with multijunction panels, obtained in laboratory conditions, is 43.5%.

Energy experts say with confidence that in a few years this figure will increase to 50%. The efficiency of thin-film plates depends, to a large extent, on the material they are made of.

Thus, thin-film solar batteries are divided into the following types:

• Silicon;
• Cadmium.

The most popular solar batteries that can be used for domestic purposes are those with silicon film wafers. The volume of such devices on the market is 80%. Their efficiency is quite low - only 10%, but they are affordable and reliable. The efficiency index is several percent higher for cadmium plates. Films with particles of selenide, copper, indium and gallium have a higher efficiency, which is equal to 15%.

What determines the efficiency of solar panels?

The efficiency of photoelectric converters is influenced by many factors. So, as noted above, the amount of energy generated depends on the structure of the converter panel and the material of their manufacture.

In addition, the efficiency of solar inverters depends on:

• Forces of solar radiation. Thus, with a decrease in solar activity, the power of solar installations decreases. In order for the batteries to provide the consumer with energy at night, they are supplied with special batteries.
• Air temperatures. Thus, solar panels with cooling devices are more productive: heating the panels negatively affects their ability to convert energy into current. So, in frosty, clear weather, the efficiency of solar batteries is higher than in sunny and hot weather.
• The angle of inclination of the device and the incidence of sunlight. To ensure maximum efficiency, the solar panel should be aimed directly at the sun's radiation. The most effective models are those whose inclination level can be changed relative to the location of the Sun.
• Weather conditions. In practice, it has been noted that in areas with cloudy, rainy weather, the efficiency of solar converters is much lower than in sunny regions.

In addition, the efficiency of solar converters is also affected by their level of cleanliness. In order for the device to work productively, its plates must consume as much solar radiation as possible. This can only be done if the devices are clean.

The accumulation of snow, dust and dirt on the screen can reduce the efficiency of the device by 7%.

It is recommended to wash screens 1-4 times a year, depending on the degree of contamination. In this case, you can use a hose with a nozzle for cleaning. Technical inspection of converter elements should be carried out every 3-4 months.

Solar power per square meter

As noted above, on average, one square meter of photovoltaic converters provides the generation of 13-18% of the power of the sun's rays falling on it. That is, under the most favorable conditions, you can get 130-180 W per square meter of solar panels.

The power of solar systems can be increased by increasing the panels and increasing the area of ​​photoelectric converters.

You can also get more power by installing panels with higher efficiency. However, the rather low (in comparison, for example, with induction converters) efficiency of available solar cells is the main obstacle to their widespread use. Increasing the power and efficiency of solar systems is the primary task of modern energy.

The most efficient solar panels: rating

The most efficient solar converters today are produced by Sharp. Three-layer, high-power, concentrating solar panels have an efficiency of 44.4%. Their cost is incredibly high, so they are used only in the aerospace industry.

The most affordable and effective are modern solar panels from the following companies:

• Panasonic Eco Solutions;
• First Solar;
• MiaSole;
• JinkoSolar;
• Trina Solar;
• Yingli Green;
• ReneSola;
• Canadian Solar.

Sun Power produces the most reliable solar inverters with an efficiency of 21.5%. The company's products are absolutely popular in commercial and industrial facilities, second only to devices from Q-Cells.

Efficiency of solar panels (video)

Modern solar panels, as environmentally friendly energy conversion devices with inexhaustible coolant, are gaining increasing popularity. Already today, devices with photoelectric converters are used for household purposes (charging phones, tablets). The efficiency of solar installations is still inferior alternative ways obtaining energy. But increasing the efficiency of converters is the primary task of modern energy.

Recently, solar energy has been developing at such a rapid pace

Recently, solar energy has been developing at such a rapid pace that in 10 years, the share of solar electricity in global annual electricity generation has increased from 0.02% in 2006 to almost one percent in 2016.

Dam Solar Park is the largest solar power plant in the world. Power 850 megawatts.

The main material for solar power plants is silicon, the reserves of which on Earth are practically inexhaustible. One problem is that the efficiency of silicon solar cells leaves much to be desired. The most efficient solar panels have an efficiency of no more than 23%. And the average efficiency rate ranges from 16% to 18%. Therefore, researchers around the world involved in the field of solar photovoltaics are working to free solar photoconverters from the image of a supplier of expensive electricity.

A real struggle has unfolded to create a solar supercell. The main criteria are high efficiency and low cost. The National Renewable Energy Laboratory (NREL) in the USA even periodically issues a newsletter reflecting the interim results of this struggle. And each episode shows the winners and losers, the outsiders and the upstarts who accidentally got involved in this race.

Leader: solar multilayer cell

These helium converters resemble a sandwich of different materials, including perovskite, silicon and thin films. In this case, each layer absorbs light only of a certain wavelength. As a result, these multilayer helium cells, with an equal working surface area, produce significantly more energy than others.

The record-breaking efficiency of multilayer photoconverters was achieved at the end of 2014 by a joint German-French research team led by Dr. Frank Dimroth at the Fraunhofer Institute for Solar Energy Systems. An efficiency of 46% was achieved. This fantastic efficiency value was confirmed by an independent study at NMIJ/AIST - the largest metrology center in Japan.

Multilayer solar cell. Efficiency – 46%

These cells are made up of four layers and a lens that concentrates sunlight onto them. The disadvantages include the presence of germanium in the structure of the substrate, which slightly increases the cost of the solar module. But all the shortcomings of multilayer cells can ultimately be eliminated, and researchers are confident that in the very near future their development will leave the walls of laboratories and enter the big world.

Rookie of the Year - Perovskite

Quite unexpectedly, a newcomer intervened in the race of leaders - perovskite. Perovskite is the general name for all materials that have a certain cubic crystal structure. Although perovskites have been known for a long time, research into solar cells made from these materials only began between 2006 and 2008. Initial results were disappointing: the efficiency of perovskite photoconverters did not exceed 2%. At the same time, calculations showed that this figure could be an order of magnitude higher. Indeed, after a series of successful experiments, Korean researchers in March 2016 received a confirmed effectiveness of 22%, which in itself became a sensation.

Perovskite solar cell

The advantage of perovskite cells is that they are more convenient to work with and easier to produce than similar silicon cells. With mass production of perovskite photoconverters, the price of one watt of electricity could reach $0.10. But experts believe that as long as perovskite helium cells reach maximum efficiency and begin to be produced in industrial quantities, the cost of a “silicon” watt of electricity can be significantly reduced and reach the same level of $0.10.

Experimental: quantum dots and organic solar cells

This type of solar photoconverter is still at an early stage of development and cannot yet be considered as a serious competitor to existing helium cells. However, the developer, the University of Toronto, claims that according to theoretical calculations, the efficiency of solar cells based on nanoparticles - quantum dots - will be above 40%. The essence of the invention of Canadian scientists is that nanoparticles - quantum dots - can absorb light in different spectral ranges. By changing the size of these quantum dots, it will be possible to select the optimal operating range of the photoconverter.

Solar cell based on quantum dots

And considering that this nanolayer can be applied by spraying onto any, including transparent, substrate, promising prospects are visible in the practical application of this discovery. And although today laboratories have achieved an efficiency rate of only 11.5% when working with quantum dots, no one doubts the prospects of this direction. And the work continues.

Solar Window – new solar cells with 50% efficiency

The Solar Window company from Maryland (USA) has introduced a revolutionary “solar glass” technology that radically changes traditional ideas about solar panels.

Previously, there were reports about transparent helium technologies, as well as that this company promises to significantly increase the efficiency of solar modules. And, as recent events have shown, these were not just promises, but 50% efficiency - no longer just the theoretical delights of the company's researchers. While other manufacturers are just entering the market with more modest results, Solar Window has already presented its truly revolutionary high-tech developments in the field of helium photovoltaics.

These developments pave the way for the production of transparent solar cells, which have significantly higher efficiency compared to traditional ones. But this is not the only advantage of the new solar modules from Maryland. New helium cells can be easily attached to any transparent surfaces (for example, windows), and can work in the shade or under artificial lighting. Due to their low cost, investments in equipping a building with such modules can pay for themselves within a year. By comparison, the payback period for traditional solar panels ranges from five to ten years, which is a huge difference.

Solar cells from the Solar Window company

The Solar Window company announced some details of the new technology for producing solar panels with such high efficiency. Of course, the main know how was left out of the equation. All helium cells are made primarily of organic material. The layers of elements consist of transparent conductors, carbon, hydrogen, nitrogen and oxygen. According to the company, the production of these solar modules is so environmentally friendly that it has 12 times less environmental impact than the production of traditional helium modules. Over the next 28 months, the first transparent solar panels will be installed in some buildings, schools, offices and skyscrapers.

If we talk about the prospects for the development of helium photovoltaics, it is very likely that traditional silicon solar cells can become a thing of the past, giving way to highly efficient, lightweight, multifunctional elements that open up the broadest horizons for helium energy. published

Date added: 04/30/2015

Nowadays, renewable energy, especially where solar energy is used, is developing very intensively. In this regard, an active search for methods and devices to increase productivity continues existing systems, allowing the most efficient conversion of solar energy into electricity. Here two directions can be distinguished - direct conversion of solar radiation into electric current, and repeated conversion of solar energy - into heat, then into mechanical work, and then into electricity. So far, better results have been achieved in the second direction - industrial solar plants with concentrators, turbines or Stirling engines show excellent productivity in converting solar energy. Thus, at a solar station operating in New Mexico with solar concentrators and Stirling engines, an output efficiency of 31.25% was obtained, taking into account energy consumption for the orientation system, etc.

But such solar installations are extremely complex and expensive, effective in conditions of very high solar insolation, and have not yet received sufficient development in the world. Therefore, direct converters of solar radiation - solar panels , occupy a leading position in the world of solar energy in terms of installations and range of applications. Productivity of serial industrial solar panels today, depending on the technology, it ranges from 7 to 20%. Technologies do not stand still, they are developing and improving, new cells are already being developed and tested, at least twice as productive as the existing ones. Let's try to briefly consider the main directions of development of photovoltaic panels, technologies and their productivity.

The vast majority of solar converter cells of modern serial photomodules are made of monocrystalline (C-Si) or polycrystalline (MC-Si) silicon. Today, such silicon photovoltaic modules occupy about 90% of the photovoltaic converter market, of which approximately 2/3 is polycrystalline silicon and 1/3 is monocrystalline. Next come solar modules, the photocells of which are made using thin-film technology - the method of deposition, or sputtering of photosensitive substances onto various substrates. A significant advantage of modules made from these elements is their lower production cost, because they require approximately 100 times less material compared to silicon wafers. And so far, the least represented are multijunction solar cells from the so-called tandem, or multijunction cells.

Market shares of photovoltaic panels of various technologies:

Silicon crystalline photomodules.

The efficiency of silicon module cells today is about 15 - 20% (polycrystals - single crystals). This figure as a whole may soon be increased by several percent. For example, SunTech Power, one of the world's largest manufacturers of crystalline silicon modules, has announced its intention to launch photo modules with 22% efficiency over the next couple of years. Existing laboratory samples of monocrystalline cells show a productivity of 25%, polycrystalline - 20.5%. The theoretical maximum efficiency of silicon unijunction (p-n) elements is 33.7%. It has not yet been achieved, and the main task of manufacturers, in addition to increasing the efficiency of cells, is to improve production technology and reduce the cost of photomodules.

Separately positioned are photo modules from Sanyo, produced using HIT (Heterojunction with Intrinsic Thin layer) technology using several layers of silicon, similar to tandem multilayer cells. The efficiency of such elements made of single-crystalline C-Si and several layers of nanocrystalline nc-Si is 23%. This is today’s highest efficiency indicator for cells of serial crystalline modules, a kind of nanosolar batteries.

Thin film solar cells efficiency.

This name refers to several different technologies, the performance of which will be briefly discussed. Currently, there are three main types of inorganic film solar cells - amorphous silicon (a-Si) films, cadmium telluride (CdTe) films, and copper indium gallium selenide (CuInGaSe2, or CIGS) films. The efficiency of modern thin-film solar cells based on amorphous silicon is about 10%, photomodules based on cadmium telluride - 10-11% (First Solar company), based on copper-indium-gallium selenide - 12-13% (Japanese solar modules SOLAR FRONTIER). Efficiency indicators of pre-series cells: CdTe have an efficiency of 15.7% (MiaSole modules), and CIGS cells have an efficiency of 18.7% (EMPA). The efficiency of individual thin-film solar cells is much higher, for example, data on the performance of laboratory samples of amorphous silicon cells is 12.2% (United Solar), CdTe cells - 17.3% (First Solar), CIGS cells - 20.5% ( ZSW). So far, solar converters based on thin films of amorphous silicon lead in production volumes among other thin-film technologies - the global market volume of thin-film Si cells is about 80%, solar cells based on cadmium telluride are about 18% of the market, and copper-indium-gallium selenide is 2% market. This is due, first of all, to the cost and availability of raw materials, as well as higher stability of characteristics than in multilayer structures. After all, silicon is one of the most common elements in the earth’s crust, while indium (CIGS elements) and tellurium (CdTe elements) are scattered and mined in small quantities. In addition, cadmium (CdTe cells) is toxic, although all manufacturers of such solar modules guarantee complete recycling of their products. Also, the degradation process in the elements of thin-film modules proceeds faster than crystalline cells. Further development of photoelectric converters based on inorganic thin films is associated with the improvement of production technology and stabilization of their parameters.

Thin-film solar cells also include organic/polymer thin-film photosensitive elements and sensitized dyes. In this direction, the commercial use of solar cells is still limited, everything is at the laboratory stage, as well as in improving the technology for future mass production. A number of sources have stated that the efficiency of elements based on organic converters has reached more than 10%: German company Heliatek -10.7%, University of California UCLA - 10.6%. A group of scientists from a laboratory at EPFL obtained an efficiency of 12.3% for cells made from sensitized dyes. In general, the direction of organic thin-film elements, as well as photosensitive dyes, is considered one of the most promising. Statements are regularly made about achieving another efficiency record, technology going beyond the walls of laboratories, and soon covering all available surfaces with highly efficient and cheap solar converters - companies Konarka, Dyesol, Solarmer Energy. Work is focused on increasing the stability of characteristics and reducing the cost of technology.

Multijunction (multilayer, tandem) solar panels characteristics.

Cells of such elements contain layers of various materials, forming several p-n junctions. An ideal solar cell would, in theory, have hundreds of different layers (pn junctions), each tuned to a small range of wavelengths of light across the entire spectrum, from ultraviolet to infrared. Each transition absorbs solar radiation at a specific wavelength, thus covering the entire spectrum. The main materials for such elements are gallium compounds (Ga) - indium gallium phosphide, gallium arsenide, etc.

One of the private solutions for converting the entire solar spectrum is the use of prisms that decompose sunlight into spectra, concentrating on single-junction elements with different ranges of radiation conversion. Despite the fact that research in the field of multijunction solar cells has been going on for two decades, and photomodules from such cells operate successfully in space (solar batteries of the Mir station, Mars Exploration Rover, etc.), their practical earthly use has begun relatively recently. The first commercial products based on such elements entered the market several years ago and showed excellent results, and research in this direction is constantly attracting attention. The fact is that the theoretical efficiency of two-layer cells can be 42% efficiency, three-layer cells 49%, and cells with an infinite number of layers - 68% of unfocused sunlight. The productivity limit of cells with an infinite number of layers is 86.8% when applying concentrated solar radiation. Today, practical efficiency results for multijunction cells are on the order of 30% in unfocused sunlight. This is not enough to offset the cost of producing such cells - the cost of a multijunction cell is approximately 100 times higher than that of a silicon cell of similar area, so multijunction cell module designs use concentrators to focus light 500 to 1000 times. A concentrator in the form of a Fresnel lens and a parabolic mirror collects sunlight from an area 1000 times larger than the cell area. The total cost of photomodules made from multijunction cells using concentrators (CPV) is significantly reduced in price due to inexpensive lenses and substrates, compensating for the high cost of production of the cell itself. At the same time, cell productivity increases up to 40%.

Solar batteries characteristics. For example, the efficiency of SolFocus cells measuring 5.5 mm x 5.5 mm is 40% when using concentrators; and the average cell sizes in CPV systems range from 5.5 mm x 5.5 mm to 1 cm x 1 cm. What does it have to do with the production of 1 cm? cells require 1/1000th of the raw material compared to a cell of similar productivity made from crystalline silicon. In order for multi-junction cells to operate with maximum efficiency, a constant high intensity of solar radiation is required; for this, two-axis orientation systems of CPV systems are used. The locations for deploying solar farms based on modules from multi-junction cells with concentrators are regions with high solar insolation.

The maximum efficiency of multijunction cells, obtained in laboratory conditions using concentrators, is currently 43.5% (Solar Junction), and is predicted to increase in the next couple of years to 50%.

As we can see, today there are solar cells with high productivity, manufactured using various technologies, and the main task of manufacturers is to reduce the cost of the final product and adapt laboratory research for mass production. Despite the low consumption of raw materials in thin-film solar cells, the cost of some components is different types quite high, just as the production technologies themselves are energy-intensive. The long-term stability of the parameters remains questionable. Multijunction solar cells are still very expensive, for maximum efficient work which also require an increased concentration of solar radiation. Therefore, crystalline silicon elements will in the near future hold a leading position in the photovoltaic converter market, decreasing in price. They will only be replaced by efficient and cheap thin-film modules, possibly made from polymer semiconductors or photosensitive dyes. But forecasting the development of this or that technology is not a rewarding task. Wait and see.

Billions of kilowatts of solar energy reach our planet every day. People have long begun to use this energy for their needs. With the progress of progress, solar panels began to be used to convert the energy of sunlight. But are these devices effective? How much is the efficiency of solar panels, and what does it depend on? What is their payback period and how can you calculate the profitability of using solar panels? These questions concern everyone who is planning or has already decided to purchase solar panels, so this article is devoted to this pressing topic.

Let's briefly look at what the operating principle of solar panels is based on. It is based on the physical property of semiconductors. Due to the knocking out of electrons from the outer orbit of atoms by light photons, a sufficiently large number of free electrons are formed. After the circuit is closed, an electric current occurs. But, as a rule, one or two solar cells are not enough to generate sufficient power, therefore, solar modules most often include several solar panels. The more solar cells are connected together, that is, the larger the area of ​​the solar panels, the greater the power they produce. In addition to the area of ​​the panels, the intensity of sunlight and the angle of incidence of the rays have a noticeable impact on the power produced.

Let's understand the concept of efficiency

The efficiency value of a panel is obtained by dividing the power of electrical energy by the power of sunlight falling on the panel. Today, the average value of this indicator in practice is 12-25%, but in theory this figure is close to 80-85%. What is the reason for such a big difference? First of all, it depends on the materials used to make solar panels. As is already known, the main element included in the panels is silicon. One of the main disadvantages of this substance is its ability to absorb only infrared radiation, that is, the energy of ultraviolet rays is wasted. Therefore, one of the main directions in which scientists are working, trying to increase the efficiency of solar panels, is the development of multilayer modules.

Multilayer batteries are a structure consisting of layers of different materials. They are selected based on quanta of different energies. That is, one layer absorbs green energy, the second - blue, the third - red. In theory, various combinations of these layers can give an efficiency value of 87%. But this, unfortunately, is just a theory. As practice shows, the manufacture of such structures on a production scale is a very labor-intensive task, and the cost of such modules is very high.

The efficiency of solar modules is also affected by the type of silicon used. Panels made from monocrystalline silicon have a higher efficiency than panels made from polycrystalline silicon. But the price of monocrystalline batteries is higher.

The basic rule: with a higher efficiency, to generate electricity of a given power, a module of a smaller area will be required, that is, a smaller number of photocells will be included in the solar panel.

How quickly will solar panels pay for themselves?

The cost of solar panels today is quite high. And taking into account the low efficiency of panels, the issue of their payback is very relevant. The service life of batteries powered by solar energy is about 25 years or more. We’ll talk about what causes such a long service life a little later, but for now let’s clarify the question raised above.

The payback period is affected by:

• Type of equipment selected. Single-layer photocells have lower efficiency compared to multilayer ones, but also have a much lower price.
• Geographical location, that is, the more sunlight in your area, the faster the installed module will pay for itself.
• Equipment cost. The more money you spent on purchasing and installing the elements that make up the solar energy saving system, the longer the payback period.
• The cost of energy resources in your region.

The average payback period for the countries of Southern Europe is 1.5-2 years, for the countries of Central Europe - 2.5-3.5 years, and in Russia the payback period is approximately 2-5 years. In the near future, the efficiency of solar panels will increase significantly, this is due to the development of more advanced technologies that will increase efficiency and reduce the cost of panels. And as a result, the period during which the solar energy saving system will pay for itself will also decrease.

How long will solar panels last?

Solar panels do not contain mechanical moving parts, so they are quite reliable and durable. As mentioned above, their service life is more than 25 years. At correct operation they can last 50 years. The big advantage is that such a long service life does not require major breakdowns; you just need to systematically clean the photocell mirrors from dust and other contaminants. This is necessary for better energy absorption, and, consequently, for a higher efficiency rate.

A long service life is one of the main criteria when deciding whether to purchase solar panels or not. After the batteries pay for themselves, the electrical energy you receive will be absolutely free. Even if the payback period is maximum (about 6 years), you will not pay for energy resources for at least 20-25 years.

Latest developments that increase efficiency

Almost every day, scientists around the world announce the development of a new method to increase the efficiency of solar modules. Let's get acquainted with the most interesting of them. Last year, Sharp introduced a solar cell to the public that was 43.5% efficient. They were able to achieve this figure by installing a lens to focus energy directly into the element.

German physicists are not far behind the Sharp company. In June 2013, they presented their photocell with an area of ​​only 5.2 square meters. mm, consisting of 4 layers of semiconductor elements. This technology made it possible to achieve an efficiency of 44.7%. Maximum efficiency in this case is also achieved by placing a concave mirror at focus.

In October 2013, the results of the work of scientists from Stanford were published. They have developed a new heat-resistant composite that can increase the performance of solar cells. The theoretical efficiency value is about 80%. As we wrote above, semiconductors that contain silicon are capable of absorbing only IR radiation. So, the action of the new composite material is aimed at converting high-frequency radiation into infrared.

The next were English scientists. They have developed technology that can increase the efficiency of cells by 22%. They proposed placing aluminum nanospikes on the smooth surface of thin-film panels. This metal was chosen because sunlight is not absorbed by it, but, on the contrary, is scattered. Consequently, the amount of solar energy absorbed increases. Hence the increase in solar battery performance.

Here are only the main developments, but the matter is not limited to them. Scientists are fighting for every tenth of a percent, and so far they have succeeded. Let's hope that in the near future the efficiency of solar panels will be at the proper level. After all, then the benefits from using the panels will be maximum.

The article was prepared by Abdullina Regina

Moscow is already using new technologies for lighting streets and parks, I think the economic efficiency has been calculated there: