Solar sources of electrical energy. The principle of solar energy conversion, its application and prospects

Without energy, life on the planet is impossible. The physical law of conservation of energy says that energy cannot arise from nothing and does not disappear without a trace. It can be obtained from natural resources such as coal, natural gas, or uranium and converted into usable forms, such as heat or light. In the world around us we can find various forms energy storage, but the most important for a person is the energy that the sun's rays give - solar energy.

solar energy refers to renewable energy sources, that is, it is restored without human intervention, in a natural way. It is one of the environmentally friendly energy sources that does not pollute environment. Application possibilities solar energy virtually unlimited and scientists around the world are working to develop systems that expand the possibilities of using solar energy.

One square meter of the Sun emits 62,900 kW of energy. This roughly corresponds to the power of 1 million electric lamps. Such a figure is impressive - the Sun gives the Earth 80 thousand billion kW every second, that is, several times more than all the power plants in the world. Before modern science the task is to learn how to use the solar energy most fully and efficiently, as the safest. Scientists believe that the ubiquitous use solar energy is the future of humanity.

The world's reserves of open deposits of coal and gas, at such rates of their use as today, should be depleted in the next 100 years. It has been calculated that in the yet unexplored deposits, the reserves of combustible minerals would be enough for 2-3 centuries. But at the same time, our descendants would be deprived of these energy carriers, and the products of their combustion would cause enormous damage to the environment.

Atomic energy has huge potential. However, the Chernobyl accident in April 1986 showed what serious consequences the use of nuclear energy can entail. The public around the world has recognized that the use of atomic energy for peaceful purposes is economically justified, but the strictest safety measures must be observed when using it.

Therefore, the cleanest, safest source of energy is the Sun!

solar energy can be converted into useful energy through the use of active and passive solar energy systems.

Passive solar energy systems.

The most primitive way of passive use solar energy- it is dyed dark color water container. dark color, accumulating solar energy, turns it into heat - the water heats up.

However, there are more advanced methods of passive use. solar energy. Building technologies have been developed that, when designing buildings, taking into account climatic conditions, and selecting building materials, make the most of solar energy for heating or cooling, building lighting. With such a design, the building structure itself is a collector, accumulating solar energy.

So, in 100 AD, Pliny the Younger built a small house in northern Italy. In one of the rooms the windows are made of mica. It turned out that this room was warmer than the others and needed less firewood to heat it. In this case, mica acted as an insulator that retained heat.

Modern building designs take into account the geographical location of buildings. So, a large number of south-facing windows are provided in the northern regions to allow more sunlight and heat to enter, and limit the number of windows on the east and west sides to limit sunlight in the summer. In such buildings, window orientation and location, thermal load and thermal insulation are a single design system in the design.

Such buildings are environmentally friendly, energy independent and comfortable. There is a lot of natural light in the rooms, a connection with nature is more fully felt, and electricity is also significantly saved. Heat in such buildings is retained due to the selected heat-insulating materials of walls, ceilings, floors. These first "solar" buildings gained immense popularity in America after World War II. Subsequently, due to the decline in oil prices, interest in the design of such buildings faded somewhat. However, now, due to the global environmental crisis, there has been an increase in attention to environmental projects with renewable energy systems increased again.

Active Solar Energy Systems

At the heart of active usage systems solar energy solar collectors are used. Collector, absorbing solar energy, converts it into heat, which heats buildings through the coolant, heats water, can convert it into electrical energy, etc. Solar collectors can be used in all processes in industry, agriculture, domestic needs, where heat is used.

Types of collectors

it simplest form solar collectors. Its design is extremely simple and resembles the effect of an ordinary greenhouse, which is in any suburban area. Do a little experiment. On a sunny winter day, put any object on the windowsill so that the sun's rays fall on it and after a while put your palm on it. You will feel that this object has become warm. And outside the window it can be - 20! It is on this principle that the work of a solar air collector is based.

The main element of the collector is a heat-insulated plate made of any material that conducts heat well. The plate is painted in dark color. The sun's rays pass through the transparent surface, heat the plate, and then transfer heat to the room with an air flow. The air passes by natural convention or by means of a fan, which improves heat transfer.

However, the disadvantage of this system is that additional costs are required for the operation of the fan. These collectors operate during daylight hours, so they cannot replace the main source of heating. However, if you mount the collector in the main source of heating or ventilation, its efficiency increases disproportionately. Solar air collectors can also be used for desalination sea ​​water, which reduces its cost to 40 eurocents per cubic meter.

Solar collectors can be flat and vacuum.

The collector consists of an element that absorbs solar energy, a coating (glass with reduced content metal), pipeline and heat-insulating layer. A transparent coating protects the case from adverse climatic conditions. Inside the case, the panel of the solar energy absorber (absorber) is connected to the coolant, which circulates through the pipes. The pipeline can be either in the form of a lattice or in the form of a serpentine. The coolant moves through them from the inlet to the outlet pipes, gradually heating up. The absorber panel is made of a metal that conducts heat well (aluminum, copper).

The collector captures the heat, converting it into thermal energy. Such collectors can be mounted in the roof or placed on the roof of the building, or they can be placed separately. This will give the design of the site a modern look.

Vacuum solar collector

Vacuum collectors can be used all year round. The main element of the collectors are vacuum tubes. Each of them consists of two glass tubes. The pipes are made of borosilicate glass, and the inside is coated with a special coating that provides heat absorption with minimal reflection. Air is pumped out of the space between the tubes. A barium getter is used to maintain the vacuum. In good condition, the vacuum tube is silver in color. If it looks white, then the vacuum is gone and the tube needs to be replaced.

The vacuum collector consists of a set of vacuum tubes (10-30) and transfers heat to the storage tank through an antifreeze liquid (heat carrier). The efficiency of vacuum collectors is high:

- in cloudy weather, because vacuum tubes can absorb the energy of infrared rays that pass through clouds

- can work at sub-zero temperatures.

Solar panels.

A solar battery is a set of modules that receive and convert solar energy, including thermal energy. But this term has traditionally been assigned to phytoelectric converters. Therefore, when we say "solar battery" we mean a phytoelectric device that converts solar energy into electrical energy.

Solar panels are capable of generating electrical energy continuously or accumulating it for further use. For the first time, photovoltaic batteries were used in space satellites.

The advantage of solar panels is the maximum simplicity of design, simple installation, minimal maintenance requirements, and a long service life. Installation does not require additional space. The only condition is not to shade them for a long time and remove dust from the work surface. Modern solar panels are able to keep working for decades! It is hard to find a system so safe, effective and with such a long duration of action! They produce energy throughout the day, even on cloudy days.

Solar panels have their drawbacks in application:

- sensitivity to pollution. (If the battery is placed at a 45 degree angle, it will be cleaned by rain or snow, thus no additional maintenance is required)

- sensitivity to high temperature. (Yes, when heated to 100 - 125 degrees, the solar panel may even turn off and a cooling system may be required. The ventilation system will consume a small fraction of the energy generated by the battery. Modern designs of solar panels provide a system for the outflow of hot air.)

- high price. (Taking into account the long service life of solar panels, it will not only pay for its purchase costs, but also save money on electricity consumption, save tons of traditional fuels, while being environmentally friendly)

The use of solar energy systems in construction.

In modern architecture, it is increasingly planned to build houses with built-in rechargeable solar energy sources. Solar panels are installed on the roofs of buildings or on special supports. These buildings use a quiet, reliable and safe energy source - the Sun. Solar energy is used for lighting, space heating, air cooling, ventilation, and electricity generation.

We present several innovative architectural projects using solar systems.

The use of solar energy systems in the world.

Usage systems solar energy perfect and environmentally friendly. There is a huge demand for them all over the world. All over the world, people are beginning to abandon the use of traditional fuels due to rising gas and oil prices. For example, in Germany in 2004. 47% of homes had solar collectors for water heating.

In many countries of the world, state programs for the development of the use of solar energy. In Germany, this is the 100,000 Solar Roofs program, in the United States, a similar program is the Million Solar Roofs. In 1996 architects from Germany, Austria, Great Britain, Greece and other countries have developed a European Charter on solar energy in construction and architecture. In Asia, China leads the way with modern technologies solar collector systems are being introduced into the construction of buildings and the use solar energy in industry.

A fact that says a lot: one of the conditions for joining the European Union is an increase in the share of alternative sources in the country's energy system. In 2000 60 million square kilometers of solar collectors worked in the world, by 2010 the area had increased to 300 million square kilometers.

Experts note that the systems market solar energy on the territory of Russia, Ukraine and Belarus is only being formed. Solar systems have never been produced on a large scale, because raw materials were so cheap that expensive equipment for solar systems was not in demand ... The production of collectors, in Russia, for example, has almost completely ceased.

In connection with the rise in price of traditional energy carriers, there has been a revival of interest in the use of solar systems. In a number of regions of these countries, experiencing a shortage of energy resources, local programs for the use of solar systems are being adopted, but solar systems are practically unknown to the wide consumer market.

The main reason for the slow development of the market for the sale and use of solar systems is, firstly, their high initial cost, and secondly, the lack of information about the possibilities of solar systems, advanced technologies for their use, about the developers and manufacturers of solar systems. All this cannot make it possible to correctly assess the effectiveness of the use of systems operating on solar energy.

It must be borne in mind that the solar collector is not the final product. To obtain the final product - heat, electricity, hot water - it is necessary to go from design, installation to commissioning of solar systems. The little available experience with solar collectors shows that this work is no more difficult than installing traditional heating, but the economic efficiency is much higher.

In Belarus, Russia, Ukraine, there are many companies involved in the design and installation of heating equipment, but today traditional energy carriers have priority. Development economic processes, world experience in using systems solar energy shows that the future belongs to alternative energy sources. For the near future, it can be noted that solar systems are a new, practically unoccupied position in our market.

The sun is an inexhaustible, environmentally safe and cheap source of energy. According to experts, the amount of solar energy that reaches the Earth's surface during a week exceeds the energy of all the world's oil, gas, coal and uranium reserves 1 . According to academician Zh.I. Alferov, “humanity has a reliable natural thermonuclear reactor - the Sun. It is a star of the Zh-2 class, very average, of which there are up to 150 billion in the Galaxy. But this is our star, and it sends huge powers to Earth, the transformation of which allows us to satisfy almost any energy demand of mankind for many hundreds of years.” Moreover, solar energy is "clean" and does not have a negative impact on the planet's ecology 2 .

An important point is the fact that the raw material for the manufacture of solar cells is one of the most common elements - silicon. In the earth's crust, silicon is the second element after oxygen (29.5% by mass) 3 . According to many scientists, silicon is the "oil of the twenty-first century": for 30 years, one kilogram of silicon in a photovoltaic plant generates as much electricity as 75 tons of oil in a thermal power plant.

However, some experts believe that solar energy cannot be called environmentally friendly due to the fact that the production of pure silicon for photovoltaics is a very “dirty” and very energy-intensive production. Along with this, the construction of solar power plants requires the allocation of vast lands, comparable in area to hydroelectric reservoirs. Another disadvantage of solar energy, according to experts, is high volatility. Ensuring the efficient operation of the energy system, the elements of which are solar power plants, is possible provided:
- the presence of significant reserve capacities using traditional energy carriers that can be connected at night or on cloudy days;
- conducting large-scale and costly modernization of power grids 4 .

Despite this shortcoming, solar energy continues its development in the world. First of all, in view of the fact that radiant energy will become cheaper and in a few years will be a significant competitor to oil and gas.

At the present moment in the world there are photovoltaic installations, converting solar energy into electrical energy based on the direct conversion method, and thermodynamic installations, in which solar energy is first converted into heat, then in the thermodynamic cycle of a heat engine it is converted into mechanical energy, and in the generator it is converted into electrical energy.

Solar cells as a source of energy can be used:
- in industry (aviation industry, automotive industry, etc.),
- in agriculture,
- in the household sector,
- in the construction industry (for example, eco-houses),
- at solar power plants,
- in autonomous video surveillance systems,
- in autonomous lighting systems,
- in the space industry.

According to the Energy Strategy Institute, the theoretical potential of solar energy in Russia is more than 2,300 billion tons of standard fuel, the economic potential is 12.5 million tons of fuel equivalent. The potential of solar energy entering the territory of Russia for three days exceeds the energy of the entire annual electricity production in our country.
Due to the location of Russia (between 41 and 82 degrees north latitude), the level of solar radiation varies significantly: from 810 kWh/m 2 per year in remote northern regions to 1400 kWh/m 2 per year in the southern regions. Large seasonal fluctuations also influence the level of solar radiation: at a width of 55 degrees, solar radiation in January is 1.69 kWh / m 2, and in July - 11.41 kWh / m 2 per day.

The potential of solar energy is greatest in the southwest (Northern Caucasus, the region of the Black and Caspian Seas) and in Southern Siberia and the Far East.

The most promising regions in terms of the use of solar energy: Kalmykia, Stavropol Territory, Rostov Region, Krasnodar Territory, Volgograd Region, Astrakhan region and other regions in the southwest, Altai, Primorye, Chita region, Buryatia and other regions in the southeast. Moreover, some areas of Western and Eastern Siberia and Far East surpasses the level of solar radiation of the southern regions. So, for example, in Irkutsk (52 degrees north latitude) the level of solar radiation reaches 1340 kWh/m2, while in the Republic of Yakutia-Sakha (62 degrees north latitude) this figure is 1290 kWh/m2. 5

Currently, Russia has advanced technologies for converting solar energy into electrical energy. There are a number of enterprises and organizations that have developed and are improving the technology of photoelectric converters: both on silicon and on multijunction structures. There are a number of developments in the use of concentrating systems for solar power plants.

The legislative framework in the field of supporting the development of solar energy in Russia is in its infancy. However, the first steps have already been taken:
- July 3, 2008: Government Decree No. 426 "On the qualification of a generating facility operating on the basis of the use of renewable energy sources";
- January 8, 2009: Decree of the Government of the Russian Federation N 1-r "On the Main Directions of State Policy in the Field of Increasing the Energy Efficiency of the Electricity Industry Based on the Use of Renewable Energy Sources for the Period up to 2020"

Targets were approved to increase by 2015 and 2020 the share of RES in the overall level of the Russian energy balance to 2.5% and 4.5%, respectively 6 .

According to various estimates, at the moment in Russia the total amount of solar generation capacity put into operation is no more than 5 MW, most of which falls on households. The largest industrial facility in the Russian solar power industry is a 100 kW solar power plant commissioned in the Belgorod region in 2010 (for comparison, the largest solar power plant in the world is located in Canada with a capacity of 80,000 kW).

Two projects are currently being implemented in Russia: the construction of solar parks in the Stavropol Territory (capacity - 12 MW) and in the Republic of Dagestan (10 MW) 7 . Despite the lack of support for renewable energy, a number of companies are implementing small projects in the field of solar energy. For example, Sakhaenergo installed a small station in Yakutia with a capacity of 10 kW.

There are small installations in Moscow: in Leontievsky Lane and on Michurinsky Prospekt, entrances and courtyards of several houses are illuminated with the help of solar modules, which reduced lighting costs by 25%. On Timiryazevskaya Street, solar panels are installed on the roof of one of the bus stops, which provide a reference and information transport system and Wi-Fi.

The development of solar energy in Russia is due to a number of factors:

1) climatic conditions: this factor affects not only the year of reaching grid parity, but also the choice of the solar installation technology that is best suited for a particular region;

2)governmental support: the presence of legally established economic incentives for solar energy is critical to
its development. Among the types of state support that are successfully used in a number of European countries and the USA, one can distinguish: a feed-in tariff for solar power plants, subsidies for the construction of solar power plants, various options for tax incentives, compensation for part of the costs of servicing loans for the purchase of solar installations;

3)cost of SFEU (solar photovoltaic installations): Today, solar power plants are one of the most expensive electricity generation technologies in use. However, as the cost of 1 kWh of generated electricity decreases, solar energy becomes competitive. Demand for SPPM depends on the decrease in the cost of 1W of installed capacity of SPPM (~$3,000 in 2010). Cost reduction is achieved by increasing efficiency, reducing technological costs and reducing the profitability of production (the impact of competition). The potential for reducing the cost of 1 kW of power depends on the technology and ranges from 5% to 15% per year;

4) environmental standards: the solar energy market may be positively affected by the tightening of environmental regulations (restrictions and fines) due to a possible revision of the Kyoto Protocol. Improving the mechanisms for the sale of emission allowances can provide a new economic impetus for the SFE market;

5) balance of demand and supply of electricity: implementation of existing ambitious plans for the construction and reconstruction of generating and power grid
capacity of companies spun off from RAO "UES of Russia" in the course of the industry reform, will significantly increase the supply of electricity and may increase pressure on the price
in the wholesale market. However, the retirement of old capacity and the simultaneous increase in demand will entail an increase in the price;

6)presence of problems with technological connection: delays in fulfilling applications for technological connection to the centralized power supply system are an incentive to switch to alternative energy sources, including SFEU. Such delays are determined both by an objective lack of capacity, and by the inefficiency of organizing technological connection by grid companies or by the lack of financing of technological connection from the tariff;

7) local government initiatives: regional and municipal governments can implement their own programs for the development of solar energy or, more generally, renewable / non-traditional energy sources. Today, such programs are already being implemented in the Krasnoyarsk and Krasnodar Territories, the Republic of Buryatia, etc.;

8) development of own production: Russian production SFEU can provide positive influence on the development of Russian consumption of solar energy. Firstly, due to its own production, the general awareness of the population about the availability of solar technologies and their popularity is increasing. Secondly, the cost of SFEM for end users is reduced by reducing the intermediate links of the distribution chain and by reducing the transport component 8 .

The sun plays an exceptional role in the life of the Earth. The entire organic world of our planet owes its existence to the Sun. The sun is not only a source of light and heat, but also the original source of many other types of energy (energy of oil, coal, water, wind).

Since the appearance on earth, man began to use the energy of the sun. According to archaeological data, it is known that for housing, preference was given to quiet places, closed from cold winds and open to the sun's rays.

Perhaps the first known solar system can be considered the statue of Amenhotep III, dating back to the 15th century BC. Inside the statue there was a system of air and water chambers, which under the sun's rays set in motion a hidden musical instrument. AT Ancient Greece worshiped Helios. The name of this god today formed the basis of many terms related to solar energy.

The problem of providing electrical energy to many sectors of the world economy, the constantly growing needs of the world's population is now becoming more and more urgent.

General information about the Sun

The Sun is the central body of the Solar System, a hot plasma ball, a typical G2 dwarf star.

Characteristics of the Sun

• Mass MS~2*1023 kg
• RS~629 thousand km
• V \u003d 1.41 * 1027 m3, which is almost 1300 thousand times greater than the volume of the Earth,
• average density 1.41*103 kg/m3,
• luminosity LS=3.86*1023 kW,
• effective surface temperature (photosphere) 5780 K,
• the rotation period (synodic) varies from 27 days at the equator to 32 days. at the poles
• acceleration free fall 274 m / s2 (with such a huge acceleration of gravity, a person weighing 60 kg would weigh more than 1.5 tons).

In the central part of the Sun there is a source of its energy, or, figuratively speaking, that "stove" that heats it and does not allow it to cool down. This area is called the core (see Fig. 1). In the nucleus, where the temperature reaches 15 MK, energy is released. The core has a radius of no more than a quarter of the total radius of the Sun. However, half of the solar mass is concentrated in its volume and almost all the energy that supports the glow of the Sun is released.

Immediately around the nucleus, a zone of radiant energy transfer begins, where it propagates through the absorption and emission of portions of light by matter - quanta. It takes a very long time for a quantum to seep through the dense solar matter to the outside. So if the stove inside the Sun suddenly went out, then we would know about it only millions of years later.

On its way through the inner solar layers, the energy flow encounters a region where the opacity of the gas increases greatly. This is the convective zone of the Sun. Here, energy is no longer transferred by radiation, but by convection. The convective zone begins approximately at a distance of 0.7 radius from the center and extends almost to the most visible surface of the Sun (photosphere), where the transfer of the main energy flux again becomes radiant.

The photosphere is the radiating surface of the Sun, which has a granular structure called granulation. Each such grain is almost the size of Germany and is a stream of hot matter that has risen to the surface. On the photosphere, one can often see relatively small dark areas - sunspots. They are 1500˚С colder than the photosphere surrounding them, the temperature of which reaches 5800˚С. Due to the difference in temperature with the photosphere, these spots appear completely black when viewed through a telescope. Above the photosphere is the next, more rarefied layer, called the chromosphere, that is, the colored sphere. The chromosphere got its name because of its red color. And, finally, above it is a very hot, but also extremely rarefied part of the solar atmosphere - the corona.

The sun is a source of energy

Our Sun is a huge luminous ball of gas, within which complex processes take place and as a result, energy is continuously released. The energy of the Sun is the source of life on our planet. The sun heats the atmosphere and the surface of the earth. Thanks to solar energy, winds blow, the water cycle is carried out in nature, the seas and oceans heat up, plants develop, animals have food. It is thanks to solar radiation that fossil fuels exist on Earth. Solar energy can be converted into heat or cold, driving force and electricity.

The sun evaporates water from the oceans, seas, from the earth's surface. It turns this moisture into water droplets, forming clouds and fogs, and then causes it to fall back to Earth in the form of rain, snow, dew or frost, thus creating a gigantic moisture cycle in the atmosphere.

Solar energy is the source of the general circulation of the atmosphere and the circulation of water in the oceans. It, as it were, creates a gigantic system of water and air heating of our planet, redistributing heat over the earth's surface.

Sunlight, falling on plants, causes the process of photosynthesis in it, determines the growth and development of plants; falling on the soil, it turns into heat, heats it, forms the soil climate, thereby giving vitality to the seeds of plants, microorganisms and living creatures that are in the soil, which without this heat would be in a state of anabiosis (hibernation).

The sun radiates a huge amount of energy - approximately 1.1x1020 kWh per second. A kilowatt hour is the amount of energy required to run a 100 watt incandescent light bulb for 10 hours. The Earth's outer atmosphere intercepts approximately one millionth of the energy emitted by the Sun, or approximately 1500 quadrillion (1.5 x 1018) kWh annually. However, only 47% of all energy, or approximately 700 quadrillion (7 x 1017) kWh, reaches the Earth's surface. The remaining 30% of solar energy is reflected back into space, about 23% evaporate water, 1% of the energy comes from waves and currents, and 0.01% from the formation of photosynthesis in nature.

Solar Energy Research

Why does the Sun shine and not cool down for billions of years? What "fuel" gives him energy? Scientists have been looking for answers to this question for centuries, and only at the beginning of the 20th century was the correct solution found. It is now known that, like other stars, it shines due to thermonuclear reactions occurring in its depths.

If the nuclei of atoms of light elements merge into the nucleus of an atom of a heavier element, then the mass of the new one will be less than the total mass of those from which it was formed. The rest of the mass is converted into energy, which is carried away by the particles released during the reaction. This energy is almost completely converted into heat. Such a reaction of the synthesis of atomic nuclei can occur only at very high pressure and temperatures above 10 million degrees. That is why it is called thermonuclear.

The main substance that makes up the Sun is hydrogen, it accounts for about 71% of the total mass of the star. Almost 27% belongs to helium and the remaining 2% to heavier elements such as carbon, nitrogen, oxygen and metals. The main "fuel" of the Sun is hydrogen. From four hydrogen atoms, as a result of a chain of transformations, one helium atom is formed. And from each gram of hydrogen involved in the reaction, 6x10 11 J of energy is released! On Earth, this amount of energy would be enough to heat 1000 m 3 of water from a temperature of 0ºC to the boiling point.

The potential of solar energy

The sun provides us with 10,000 times more free energy than is actually used worldwide. The global commercial market alone buys and sells just under 85 trillion (8.5 x 10 13) kWh of energy per year. Since it is impossible to follow the whole process, it is not possible to say with certainty how much non-commercial energy people consume (for example, how much wood and fertilizer is collected and burned, how much water is used to produce mechanical or electrical energy). Some experts estimate that such non-commercial energy accounts for one-fifth of all energy used. But even if this is true, then the total energy consumed by mankind during the year is only approximately one seven thousandth of the solar energy that hits the surface of the Earth in the same period.

In developed countries, such as the USA, energy consumption is approximately 25 trillion (2.5 x 10 13) kWh per year, which corresponds to more than 260 kWh per person per day. This is the equivalent of running more than 100 100W incandescent bulbs daily for a full day. The average US citizen consumes 33 times more energy than an Indian, 13 times more than a Chinese, two and a half times more than a Japanese and twice as much as a Swede.

The sun is one of the renewable alternative energy sources. To date, alternative heat sources are widely used in agriculture and in the domestic needs of the population.

The use of solar energy on earth plays an important role in human life. With the help of its heat, the sun, as a source of energy, heats the entire surface of our planet. Thanks to its thermal power, winds blow, the seas, rivers, lakes heat up, all life on earth exists.

Renewable heat sources, people began to use many years ago, when modern technologies did not yet exist. The sun is the most affordable source of thermal energy on earth today.

Areas of use of solar energy

Every year the use of solar energy is gaining more and more popularity. A few years ago, it was used to heat water for country houses, summer showers, and now renewable heat sources are used to generate electricity and hot water for residential buildings and industrial facilities.

To date, renewable heat sources are used in the following areas:

• in the agricultural sector, for the purpose of electrical supply and heating of greenhouses, hangars and other buildings;
• for power supply of sports facilities and medical institutions;
• in the field of aviation and space industry;
• in illumination of streets, parks, and also other city objects;
• for the electrification of settlements;
• for heating, power supply and hot water supply of residential buildings;
• for household needs.

Application features

The light emitted by the sun on earth is converted into thermal energy by means of passive as well as active systems. Passive systems include buildings, the construction of which uses such building materials that most effectively absorb the energy of solar radiation. In turn, active systems include collectors that convert solar radiation into energy, as well as photocells that convert it into electricity. Let's take a closer look at how to properly use renewable heat sources.

Passive systems

Such systems include solar buildings. These are buildings built taking into account all the features of the local climatic zone. For their construction, materials are used that make it possible to maximize the use of all thermal energy for heating, cooling, lighting residential and industrial premises. These include the following building technologies and materials: insulation, wooden floors, light-absorbing surfaces, and the orientation of the building to the south.

Such solar systems allow for the maximum use of solar energy, in addition, they quickly pay for their construction costs by reducing energy costs. They are environmentally friendly, and also allow you to create energy independence. It is because of this that the use of such technologies is very promising.

Active systems

This group includes collectors, accumulators, pumps, pipelines for heat supply and hot water supply in everyday life. The former are installed directly on the roofs of houses, while the rest are located in the basement to be used for hot water and heat supply.

solar cells

In order to more effectively implement all solar energy, solar energy sources such as photovoltaic cells, or as they are also called, solar cells, are used. On their surface, they have semiconductors, which, when exposed to the rays of the sun, begin to move, and thereby generate an electric current. This principle of current generation does not contain any chemical reactions, which allows the photocells to work for a long time.

Such photovoltaic converters as solar power sources are easy to use, as they are light in weight, easy to maintain, and are also very efficient in using solar power.

To date, solar panels, as a source of solar energy on earth, are used to generate hot water, heating and electricity in warm countries such as Turkey, Egypt and Asian countries. In our region, the sun is used as an energy source to supply electricity to autonomous power supply systems, low-power electronics and aircraft drives.

Solar collectors

The use of solar energy by collectors is that they convert radiation into heat. They are divided into the following main groups:

• Flat solar collectors. They are the most common. They are convenient to use for domestic heating needs, as well as for heating water for hot water supply;
• vacuum collectors. They are used for household needs when water is needed. high temperature. They consist of several glass tubes, passing through which the rays of the sun heat them up, and they, in turn, give off heat to the water;
• Air solar collectors. They are used for air heating, air mass recovery and for drying plants;
• Integrated collectors. The simplest models. They are used for preheating water, for example, for gas boilers. In everyday life, heated water is collected in a special tank - drives and then used for various needs.

The use of solar energy by collectors is carried out by accumulating it in the so-called modules. They are installed on the roof of buildings and consist of glass tubes and plates that are painted black to absorb more sunlight.

Solar collectors are used to heat water for hot water supply and heating residential buildings.

Advantages of solar installations

• they are completely free and inexhaustible;
• have complete safety in use;
• autonomous;
• economical, since the funds are spent only on the purchase of equipment for installations;
• their use guarantees the absence of power surges, as well as stability in the power supply;
• durable;
• easy to use and maintain.

The use of solar energy with the help of such installations is gaining popularity every year. Solar panels make it possible to save a lot of money on heating and hot water supply, besides, they are environmentally friendly and do not harm human health.

The principle of solar energy conversion, its application and prospects

There are fewer traditional energy sources in the world. Stocks of oil, gas, coal are depleted and everything goes to the fact that sooner or later they will run out. If by this time no alternative energy sources are found, then a catastrophe awaits humanity. Therefore, in all developed countries, research is underway to discover and develop new energy sources. The first is solar energy. Since ancient times, this energy has been used by people to light their homes, dry food, clothes, etc. Today, solar energy is one of the most promising sources of alternative energy. Currently, there are already quite a lot of designs that allow you to convert the energy of the sun into electrical or thermal energy. The industry is gradually growing and developing, but, like everywhere else, there are problems. All this will be discussed in this article.

Solar energy is one of the most affordable renewable sources on Earth. The use of solar energy in the national economy has a positive effect on the state of the environment, since it does not require drilling wells or developing mines to obtain it. In addition, this type of energy is free and does not cost anything. Naturally, the costs for the purchase and installation of equipment are required.

The problem is that the sun is an intermittent source of energy. So, what is required is the accumulation of energy and its use in conjunction with other energy sources. The main problem today is that modern equipment has a low efficiency of converting solar energy into electrical and thermal energy. Therefore, all developments are aimed at increasing the efficiency of such systems and reducing their cost.

By the way, a lot of resources on the planet are derived from solar energy. For example, wind, which is another renewable source, would not blow without the sun. The evaporation of water and its accumulation in rivers also occurs under the action of the sun. And water, as you know, is used by hydropower. Biofuels would also not exist without the sun. Therefore, in addition to a direct source of energy, the sun affects other areas of energy.

The sun sends radiation to the surface of our planet. Of the wide spectrum of radiation from the Earth's surface, 3 types of waves reach:

• Light. In the emission spectrum, they are approximately 49 percent;
• infrared. Their share is also 49 percent. Thanks to these waves, our planet is warming up;
• Ultraviolet. In the spectrum of solar radiation, they are approximately 2 percent. They are invisible to our eyes.

Excursion into history

How has solar energy evolved to the present day? Man has thought about the use of the sun in his activities since ancient times. Everyone knows the legend according to which Archimedes burned the enemy fleet near his city of Syracuse. He used incendiary mirrors for this. Several thousand years ago, in the Middle East, the palaces of rulers were heated with water, which was heated by the sun. In some countries, we evaporate sea water in the sun to get salt. Scientists often conducted experiments with heating devices powered by solar energy.

The first models of such heaters were produced in the XVII-XVII centuries. In particular, the researcher N. Saussure presented his version of the water heater. It is a wooden box with a glass lid. The water in this device was heated to 88 degrees Celsius. In 1774, A. Lavoisier used lenses to concentrate heat from the sun. And lenses have also appeared that allow locally to melt cast iron in a few seconds.

Batteries that convert the energy of the sun into mechanical energy were created by French scientists. At the end of the 19th century, researcher O. Musho developed an insolator that focused beams on a steam boiler using a lens. This boiler was used to operate the printing press. In the United States at that time, it was possible to create a unit powered by the sun with a capacity of 15 "horses".

For a long time, insolators were produced according to a scheme that uses the energy of the sun to turn water into steam. And the converted energy was used to do some work. The first device that converts solar energy into electrical energy was created in 1953 in the United States. It became the prototype of modern solar panels. The photoelectric effect on which their work is based was discovered back in the 70s of the 19th century.

In the thirties of the last century, Academician of the USSR A.F. Ioffe proposed the use of semiconductor photocells to convert solar energy. Battery efficiency at that time was less than 1%. It took many years before solar cells were developed with an efficiency of 10-15 percent. Then the Americans built solar panels of a modern type.

To obtain more power from solar systems, low efficiency is compensated by an increased area of ​​​​photocells. But this is not an option, since silicon semiconductors in photovoltaic cells are quite expensive. With an increase in efficiency, the cost of materials increases. This is the main obstacle to the massive use of solar panels. But as resources are depleted, their use will become more and more profitable. In addition, research to increase the efficiency of solar cells does not stop.

It is worth saying that semiconductor-based batteries are quite durable and do not require qualifications to care for them. Therefore, they are most often used in everyday life. There are also entire solar power plants. As a rule, they are created in countries with a large number of sunny days per year. This is Israel Saudi Arabia, South USA, India, Spain. Now there are absolutely fantastic projects. For example, solar power plants outside the atmosphere. There sunlight hasn't lost energy yet. That is, the radiation is proposed to be captured in orbit and then converted into microwaves. Then, in this form, the energy will be sent to the Earth.

Solar Energy Conversion

First of all, it is worth saying about how solar energy can be expressed and evaluated.

How can you estimate the amount of solar energy?

Experts use to evaluate such a value as the solar constant. It is equal to 1367 watts. This is the amount of solar energy per square meter of the planet. About a quarter is lost in the atmosphere. The maximum value at the equator is 1020 watts per square meter. Taking into account day and night, changes in the angle of incidence of rays, this value should be reduced by another three times.

Versions about the sources of solar energy were very different. At the moment, experts say that energy is released as a result of the transformation of four H2 atoms into a He nucleus. The process proceeds with the release of a significant amount of energy. For comparison, imagine that the conversion energy of 1 gram of H2 is comparable to that released when burning 15 tons of hydrocarbons.

Conversion methods

Since science today does not have devices that work on the energy of the sun in its pure form, it needs to be converted to another type. For this, devices such as solar panels and a collector were created. Batteries convert solar energy into electrical energy. And the collector generates thermal energy. There are also models that combine these two types. They are called hybrids.

• photoelectric;
• solar thermal;
• hot air;
• solar balloon power plants.

The first way is the most common. It uses photovoltaic panels that generate electricity under the influence of the sun. In most cases, they are made of silicon. The thickness of such panels is tenths of a millimeter. Such panels are combined into photovoltaic modules (batteries) and installed in the sun. Most often they are placed on the roofs of houses. In principle, nothing prevents them from being placed on the ground. It is only necessary that there are no large objects around them, other buildings and trees that can cast a shadow.

In addition to photocells, thin-film or are used to generate electrical energy. Their advantage is a small thickness, and the disadvantage is a reduced efficiency. Such models are often used in portable chargers for various gadgets.

The hot-air conversion method involves obtaining the energy of an air flow. This flow is directed to the turbogenerator. In balloon power plants, under the influence of solar energy, water vapor is generated in a balloon balloon. The surface of the balloon is covered with a special coating that absorbs the sun's rays. Such power plants are able to operate in cloudy weather and at night due to the steam supply in the balloon.

Solar energy is based on heating the surface of the energy carrier in a special collector. For example, it could be heating water for a home heating system. Not only water, but also air can be used as a heat carrier. It can be heated in the collector and fed into the ventilation system of the house.

All these systems are quite expensive, but their development and improvement is gradually continuing.

Advantages and disadvantages of solar energy

Advantages

• Is free. One of the main advantages of solar energy is that there is no charge for it. Solar panels are made using silicon, which is quite abundant;
• Not side effects. The process of energy conversion takes place without noise, harmful emissions and waste, environmental impact. This cannot be said about thermal, hydro and nuclear energy. All traditional sources harm the OS in one way or another;
• Safety and reliability. The equipment is durable (serves up to 30 years). After 20-25 years of use, solar cells give out up to 80 percent of their face value;
• Recycling. Solar panels are completely recyclable and can be reused in production;
• Ease of maintenance. The equipment is quite simple to deploy and work offline;
• Well adapted for use in private homes;
• Aesthetics. Can be installed on the roof or facade of the building without compromising the appearance;
• Well integrated as auxiliary power supply systems.