The use of solar energy. Solar energy in Russia: advantages, ways of transformation, prospects

The sun is a huge natural source of energy. Hundreds of different processes take place every minute inside this gas ball. Without the Sun, life on Earth is impossible, since it is a source of energy for all living organisms. All earthly natural processes are carried out thanks to solar energy. Atmospheric circulation, water cycle, photosynthesis, heat regulation on the planet - all this would be impossible without the Sun. The use of solar energy on Earth is as common as inhalation and exhalation for a person. But it can give humanity even more. It can be successfully used to produce industrial energy, thermal or electrical.

The potential of solar energy

Developments on the use of solar energy began in the 20th century. Since then, hundreds of studies have been carried out by scientists from all over the world. They proved that the efficiency of using solar energy can be very, very high. This source can provide energy for the entire planet much better than all the resources that exist today in the aggregate. At the same time, this type of energy is publicly available and free of charge.

Using the energy of sunlight

The reserves of natural resources capable of providing energy supply on Earth are declining every day. Therefore, active development is currently underway. various ways use of solar energy. This resource is an excellent alternative to traditional sources. Therefore, research in this area is incredibly important for society.

Achievements that exist on this moment, made it possible to create systems for the use of solar energy, which can be divided into two types:

• Active (photovoltaic systems, solar power plants and collectors).
• Passive (selection of building materials and design of premises for maximum use of sunlight energy).

The transformation and use of solar energy in this way has made it possible to use an inexhaustible resource with high productivity and payback.

The principle of operation of passive systems

There are several types of passive use of solar energy. Most of them are incredibly easy to use, yet quite effective. There are also more intricate options that help you get more benefits. For example:

• The first thing that comes to mind is the container in which the water is stored. If you paint it dark shade, then in such a simple way, solar energy will be converted into thermal energy, and the water will heat up.
• The next option is beyond the power of an ordinary person to perform on their own, as it requires a rigorous analysis of a specialist. This technology should be taken into account at the stage of designing and building a house. Based on climatic conditions, the building is designed in such a way that it works as a solar collector itself. After that, the necessary materials are selected that contribute to the maximum accumulation of solar energy.

Thanks to such methods, it becomes possible to use solar energy for heating and lighting. Also, such developments contribute to energy saving. Since such a design can not only convert solar energy, but also retain heat inside the building, which also significantly reduces costs.

Ways to actively use solar energy

Collectors are the basis of this principle of energy supply. Such equipment absorbs energy and converts it into heat, which can be used to heat a house or heat water, and also converts solar energy into electrical energy. Collectors are widely used both in industrial volume and in private areas and agriculture.

In addition to collectors, panels with photocells can be called another equipment of the active system. This device allows you to use solar energy in everyday life and on an industrial scale. Such panels are very simple, unpretentious in maintenance and durable.

Another way to actively use the energy of the sun are solar power plants. They are suitable only for large-scale conversion of radiation into thermal or electrical energy. In recent years, they have significantly gained popularity in the world and developments in this area allow expanding the capabilities and number of such stations.

Speaking about the fact that solar energy helps to save on the use of traditional resources, it is worth noting that such an advantage will become really useful people with their own private plots. Owning your own home gives you the opportunity to install energy conversion equipment that can satisfy, even if not completely, at least part of your energy needs. This will help to significantly reduce the consumption of centralized power supply and reduce costs.

Solar energy is an excellent source for such processes:

• Passive heating and cooling of the house.

We should not forget that the Sun already heats everything that exists on Earth, and your home is no exception. Therefore, it is possible to strengthen beneficial effect, making certain amendments at the construction stage, and using special techniques. Thus, you will get a house with much more comfortable heat control without much investment.

• Heating water with solar energy.

The use of solar energy to heat water is the simplest and most cheap way, accessible to man. Such equipment can be bought at reasonable prices. At the same time, they will be able to pay for themselves quickly enough, significantly reducing the cost of centralized energy supply.

• Street lighting.

This is the easiest and cheapest way to use solar energy. Special devices that absorb solar radiation during the day and illuminate areas at night are very popular among owners of private houses even now.

The solar panel, unfortunately, is not widely available. Its cost is quite high, but at the same time, it is a convenient and profitable energy resource that can be successfully used in Russian latitudes. But if your financial situation does not allow you to make such an expensive purchase, you can create such panels yourself.

How to do it?

• First of all, you will need solar photovoltaic cells. On average, for one panel they will need about 36 pieces. It is better to choose elements on single crystals, as they have a higher efficiency and a longer service life.
• The panel itself is made from plywood sheet. A bottom is cut out of it, the size of which you determine, depending on the number of photocells. Next, the panel is placed in a frame of bars.
• After that, it is required to make a substrate on which photocells will be superimposed. This can be done from fiberboard.
• Next you need to make holes. Make sure they are symmetrical.
• Next, the staining and drying procedure is carried out, which is repeated twice.
• After the substrate dries, the elements are laid out on it, and the desoldering is performed. Important point- Lay them upside down.
• At the final stage, the photocells are laid out in rows, and then everything is connected into complexes. All this is finally fixed with silicone.

In such a simple way, you can create equipment with your own hands that allows you to use solar energy in everyday life. A little effort and patience, and you will succeed.

Use of solar energy in Russia

What stage of development is it currently in? alternative energy in Russia? Unfortunately, at the present time this is happening at a very low level. So far, the country does not bring all the existing potential to life. This is strongly influenced by such an aspect as the presence of large reserves of minerals that are used for traditional energy supply.

However, the successful use of solar energy in Russia is possible. Due to the huge area, which includes different climatic zones and relief, the country has the opportunity to actively develop the production of alternative energy. With a competent and comprehensive approach, it is possible to provide a significant percentage of the total energy supply with the help of solar energy.

There have been disputes and discussions about solar energy and the prospects for its development for many years. Most consider solar energy to be the energy of the future, the hope of all mankind. A large number of companies are investing heavily in the construction of solar power plants. Solar energy is being developed in many countries of the world, considering it the main alternative to traditional energy carriers. Germany, being far from a sunny country, has become a world leader in this area. The total capacity of SES in Germany is growing year by year. Seriously engaged in developments in the field of solar energy in China. According to the optimistic forecast of the International Energy Agency, by 2050 solar power plants will be able to produce up to 20-25% of the world's electricity.
An alternative view of the prospects for solar power plants is based on the fact that the costs required for the manufacture of solar panels and battery systems are many times higher than the profit from the electricity produced by solar power plants. Opponents of this position claim that the opposite is true. Modern solar batteries are able to work without new investments for tens and even hundreds of years, the total energy produced by them is equal to infinity. That is why, in the long term, electricity generated using solar energy will become not just profitable, but super-profitable.
Where is the truth? Let's try to figure it out together with you, dear readers. We will look at modern approaches in the field of solar energy and some of the most brilliant ideas that have already been implemented to date. We will try to establish the efficiency of solar panels that are currently operating, to understand why today this efficiency is rather low.

The efficiency of solar panels in Russia
According to modern research, solar energy is about 1367 watts per square meter (solar constant). At the equator, only 1020 watts reach the earth through the atmosphere. On the territory of Russia, with the help of solar power plants (assuming that the efficiency of solar cells is 16% today), an average of 163.2 watts per square meter can be obtained.
In taking into account weather conditions, the duration of the day and night, as well as the type of installation of solar panels (the efficiency of the solar battery is not taken into account).
If a square kilometer of solar panels is installed in Moscow at an angle of 40 degrees (which is optimal for Moscow), then the annual volume of electricity generated will be 1173 * 0.16 = 187.6 GW * h. With an electricity price of 3 rubles per kWh, the notional value of the generated electricity is 561 million rubles.

The most common ways to generate electricity using the sun:

Solar thermal power stations
The huge mirrors of such solar power plants, turning, catch the sun and reflect it onto the collector. The principle of operation of such power generating stations is based on the conversion of the thermal energy of the sun into the mechanical electrical energy of a thermodynamic machine, either with the help of a gas-piston Stirling engine, or by heating water, etc.

As an example, consider the Ivanpah power plant (capacity 392 megawatts), in which the almighty Google has invested. More than two billion US dollars have been invested in the construction of a solar power plant located in California's Mojave Desert. 5612 dollars were spent for 1 kW of the installed capacity of the solar power plant. Many believe that these costs, while higher than those of coal-fired power plants, are much lower than those of nuclear power plants. But is it? First, a nuclear power plant costs between $2,000 and $4,000 per kilowatt of installed capacity, which is cheaper than the cost of building Ivanpah. Secondly, the annual electricity generation of the solar power plant is 1079 GWh, therefore, its average annual capacity is 123.1 MW. In addition, the solar power station is able to generate solar energy only during the daytime. Thus, the "average" cost of building a solar power plant comes to 17,870 dollars per 1 kW, and this is a rather significant price. Perhaps it would be more expensive to generate electricity in outer space. The construction costs of conventional power plants operating, for example, on gas, are 20-40 times lower. At the same time, unlike solar power plants, these power plants can operate continuously, producing electricity when there is a need for it, and not only during those hours when the sun is shining.
But we know that modern solar thermal power plants are capable of generating electricity around the clock, using for this a large volume of coolant heated throughout the daylight hours. Only the cost of building these stations is being tried not to advertise too much, probably because it is significant. And if batteries are included in the cost of designing and building solar power plants, especially the construction of pumped storage power plants, then the amount will increase to fantastic proportions.

silicon solar cells
Today, for the operation of solar power plants, semiconductor photocells are used, which are semiconductor diodes of a large area. A light quantum flying into the pn junction generates an electron-hole pair, while a voltage drop (of the order of 0.5V) is created at the outputs of the photodiode.
The efficiency of a silicon solar battery is about 16%. Why is the efficiency so low? In order to form an electron-hole pair, a certain energy is required. If the arriving light quantum has a low energy, then the generation of a pair will not occur. In this case, a quantum of light will simply pass through silicon, as through ordinary glass. This is why silicon is transparent to infrared light beyond 1.2 µm. If a light quantum arrives with more energy than is required for generation (green light), a pair is formed, but the excess energy will simply go nowhere. With blue and ultraviolet light (whose energy is very high), the quantum may not have time to reach the very depths p-n transition.

In order for sunlight not to be reflected from the surface of the solar battery, a special anti-reflective coating is applied to it (such a coating is also applied to the lenses of photographic lenses). The surface texture is made uneven (in the form of a comb). In this case, the light flux, reflected from the surface once, returns again.
The efficiency of photocells is increased by combining photocells based on different semiconductors and with different energies required to generate an electron-hole pair. For three-stage silicon photocells, an efficiency of 44% and even higher is achieved. The principle of operation of a three-stage photocell is based on the fact that a photocell is placed first, which effectively absorbs blue light, and transmits red and green. The second photocell absorbs green, the third absorbs IR. However, three-stage photovoltaic cells are very expensive today, therefore, cheaper single-stage photocells are widely used, which, due to the price, are ahead of three-stage ones in Watt / $.
China is developing the production of silicon solar cells at a gigantic pace, due to which the cost of one watt is reduced. In China, it is about 0.5 dollars per watt.
The main types of silicon solar cells are:
Monocrystalline
Polycrystalline
The efficiency of monocrystalline solar cells, which are more expensive, is slightly higher (by only 1%) than the efficiency of polycrystalline ones. Polycrystalline silicon solar cells today provide the cheapest cost per watt of electricity generated.
Silicon solar cells cannot last forever. Over 20 years of operation in an aggressive environment, the most advanced of them lose up to 15 percent of their original power. There is reason to believe that further degradation of solar panels slows down.

Silicon photocell and parabolic mirror
Inventors all over the world are making all sorts of attempts to increase the economic viability of solar power plants. If, for example, we take a small efficient silicon photocell and a parabolic mirror (concentrated photovoltaics), we can achieve an efficiency of 40% instead of 16, while the mirror is much cheaper than a solar battery. But in order to follow the sun, reliable mechanics are required. A huge mirror swivel dish must be securely fastened and protected from powerful wind gusts and aggressive factors. environment. The second problem is that parabolic mirrors cannot focus scattered light. If the sun has set even behind thin clouds, the power generation from the parabolic system will drop to zero. In conventional solar panels under these conditions, the generation of thermal energy is also seriously reduced, but not to zero. Solar panels with parabolic mirrors are too expensive in terms of installation cost and costly to maintain.

Round solar cells on rooftops
The American company Solyndra, with the support of the government, designed solar cells with a round shape. They were mounted on roofs painted in White color. Circular solar arrays were made by sputtering a conductive layer (in the case of Solyndra, Copper indium gallium (di)selenide was used) onto glass tubes. The actual efficiency of round batteries was about 8.5%, which is lower than cheaper silicon ones. Solyndra, which received state guarantees on a huge loan, went bankrupt. In technology, the cost-effectiveness of which was very doubtful from the very beginning, the American economy has invested considerable cash. “Successful” lobbying of inefficient technologies is not only Russian know-how.

A big problem solar energy!
It is known that solar power plants generate electricity during the day, while a huge need for electricity arises just the same in the evening. This means that without batteries, solar power plants will not be effective. In the evening peak of electricity consumption, alternative (classical) sources of electricity will have to be used. During the daytime, some traditional power plants will have to be turned off, and some will have to be kept in hot standby in case bad weather. If clouds hang over the solar power plant, the missing electricity should be provided by the backup. As a result, classical generating capacities stand in reserve and lose profit.

There is another way. It is reflected in the Desertec project - the transmission of electricity from Africa to Europe. With the help of power lines in the evening peak of electricity consumption, it is possible to transmit electricity from solar power plants, which are located in those areas of the globe where at that time the sun is at its height. But this method, prior to the transition to superconductors, requires huge financial costs, as well as all sorts of agreements between different states.

Battery use
We found that the average cost per watt produced by a solar panel is $0.50. During the day (8 hours), the battery is able to generate within 8 Wh. This energy must be conserved until the evening peak of electricity consumption.
Lithium batteries developed in China cost approximately $0.4 per Wh, so for a $0.5 solar panel, $3.2 batteries per watt would be needed, which is six times the cost of the battery itself. . Considering that a lithium battery is designed for a maximum of 2000 charge-discharge cycles, which is three to six years, we can conclude that a lithium battery is an extremely expensive solution.
The cheapest batteries are lead-acid. The wholesale price of these far from the most environmentally friendly systems is about $ 0.08 per Wh. Lead-acid batteries, as well as lithium batteries, are designed for 3-6 years of operation. The efficiency of a lead battery is 75%. This battery loses a quarter of its energy in the charge-discharge cycle. To save a day's solar energy production, you will need to purchase lead-acid batteries for $0.64. We see that this is also more than the cost of the batteries themselves.
Pumped storage power plants have been developed for modern solar power plants. During daylight hours, water is pumped into them, and at night they function like ordinary hydroelectric power plants. But the construction of these power plants (90% efficiency) is not always possible and extremely expensive.
We can draw a disappointing conclusion. Today, batteries are more expensive than solar power plants themselves. For large solar power plants, they are not provided. As electricity is generated, large solar power plants sell it to distribution networks. In the evening and at night, electricity is generated by conventional power plants.

Solar energy - what is its price today?
Take, for example, Germany - the world leader in the use of solar energy. A kilowatt of solar energy that is generated (even during the daytime, and such electricity is cheaper) is bought in this country at a price of 12 to 17.45 euro cents per kWh. Since gas-fired power plants in Germany are still under construction, operating or on hot standby, solar power plants in this country are actually just helping to save Russian gas.
The cost of Russian gas today is $450 per thousand cubic meters. From this volume of gas (generation efficiency 40%), approximately 4.32 GW of electricity can be generated. Consequently, for 1 kWh of electricity generated from the sun, Russian gas is saved in the amount of 0.104 dollars or 7.87 euro cents. Here is the fair value of solar unregulated generation. Thus, currently in Germany, solar energy is 50% subsidized by the state. Although, it should be noted that Germany is rapidly reducing the cost of generating electricity from the sun.

Drawing conclusions
The most economical solar electricity (0.5 dollars per 1 watt) is produced today with the help of solar polycrystalline batteries. All other methods of generating electricity using solar energy are much more expensive.
The problem that is key for solar energy is not the efficiency of solar panels, not the price, and not the EROEI, which is theoretically infinite. the main problem is to reduce the cost of ways to generate solar energy received during the daytime and save this energy for evening peak consumption. Indeed, at present, battery systems, the service life of which is from three to six years, are several times more expensive than the solar panels themselves.
Solar generation on a significant scale is considered today only as a way to save a small part of traditional fossil fuels in daytime. Solar energy is not yet able to fully take on the load during the evening peak hours of energy consumption and reduce the number of nuclear power plants, coal, gas and hydroelectric power plants, which should stand in reserve during the daytime, and take on a significant energy load in the evening.
If, as a result of tightening tariffs (which, for example, it would be profitable for producers of hydrogen and aluminum to start their electrolysis production during the daytime), the peak of electricity consumption shifts to daytime hours, then solar energy will have more serious prospects for development.
The cost of solar generation, which is "unregulated", is incomparable to the cost of generating electricity in conventional power plants, which are free to generate it at any time when it is needed.
The cost of solar electricity should not exceed the cost of fossil fuels saved with its help. If, for example, gas in Germany costs $450, then the price of solar generation in this country should not exceed $0.1 per kilowatt hour, otherwise solar energy in this country is unprofitable. As long as fossil fuels remain cheap and readily available, solar power generation is not economically viable.
Currently, the use of solar energy and expensive solar battery systems is economically justified only for those regions and objects where there are no other options for connecting to the power grid. For example, at a lonely standing, remote cellular station.
However, do not forget the following important factors, which inspire optimism when considering solar energy:
1. The cost of fossil fuels is steadily rising as its supply decreases.
2. Reasonable public policy makes the use of solar power plants more profitable.
3. Progress does not stand still! The efficiency of solar power plants is increasing, new technologies are being developed in the generation and accumulation of electricity.

Therefore, I would like to believe that in 3-5 years it will be possible to write a much more positive review of this energy sector!

Today, the problem of energy consumption is quite acute - the resources of the planet are not endless, and during its existence, humanity has pretty much devastated what was given by nature. At the moment, coal and oil are being actively mined, the reserves of which are becoming smaller every day. allowed humanity to take an incredible step into the future and use atomic energy, bringing along with this boon a huge danger to the entire environment.

The environmental issue is no less acute - the active extraction of resources and their further use adversely affects the state of the planet, changing not only the nature of soils, but even climatic conditions.

That is why special attention has always been paid to natural sources of energy, such as, for example, water or wind. Finally, after so many years of active research and development, humanity has “grown up” to the use of solar energy on Earth. It is about him that will be discussed further.

What is so attractive about this

Before proceeding to concrete examples, let's find out why researchers from all over the world are so interested in this type of energy production. Its main asset can be called inexhaustibility. Despite numerous hypotheses, the likelihood that a star like the Sun will go out in the near future is extremely small. This means that humanity has the opportunity to receive clean energy in a completely natural way.

The second undoubted advantage of using solar energy on Earth is the environmental friendliness of this option. The impact on the environment under such conditions will be zero, which in turn provides the whole world with a much brighter future than that which opens up with the constant extraction of limited underground resources.

Finally, special attention should be paid to the fact that the Sun represents the least danger to man himself.

How really

Now let's get to the point. The somewhat poetic name "solar energy" actually hides the conversion of radiation into electricity using specially developed technologies. This process is provided by photovoltaic cells, which humanity is extremely actively using for its own purposes, and quite successfully.

Solar radiation

It so happened historically that the noun "radiation" evokes more negative associations in a person than positive ones in connection with those man-made disasters that the world managed to survive in its lifetime. Nevertheless, the technology of using the energy of the Sun on Earth provides for working with it.

In fact, this species radiation is electromagnetic radiation, the range of which is in the range from 2.8 to 3.0 microns.

The solar spectrum so successfully used by mankind actually consists of three types of waves: ultraviolet (about 2%), about 49% are light waves, and, finally, the same amount falls on Solar energy has a small number of other components, but their role is so insignificant that they do not have a special impact on the life of the Earth.

The amount of solar energy hitting the earth

Now that the composition of the spectrum used for the benefit of mankind has been determined, one more important feature of this resource should be noted. The use of solar energy on Earth seems very promising also because it is available in fairly large quantities at almost minimal processing costs. The total amount of energy emitted by a star is extremely high, but about 47% reaches the Earth's surface, which is equal to seven hundred quadrillion kilowatt-hours. For comparison, we note that only one kilowatt-hour can provide a ten-year operation of a light bulb with a power of one hundred watts.

The power of the Sun's radiation and the use of energy on Earth, of course, depends on a number of factors: climatic conditions, the angle of incidence of rays on the surface, season and geographical location.

When and how much

It is easy to guess that the daily amount of solar energy falling on the surface of the Earth is constantly changing, since it directly depends on the position of the planet in relation to the Sun and the movement of the star itself. It has long been known that at noon the radiation is maximum, while in the morning and evening the number of rays reaching the surface is much less.

We can say with confidence that the use of solar energy will be most productive in regions as close as possible to the equatorial strip, since it is there that the difference between the highest and lowest scores minimum, which indicates the maximum amount of radiation reaching the surface of the planet. For example, in the desert African areas, the annual amount of radiation reaches an average of 2200 kilowatt-hours, while in Canada or, for example, Central Europe, the figures do not exceed 1000 kilowatt-hours.

Solar energy in history

If you think as broadly as possible, attempts to "tame" the great luminary that warms our planet began in ancient times during paganism, when each element was embodied by a separate deity. However, of course, then the use of solar energy was out of the question - magic reigned in the world.

The topic of using the energy of the Sun on Earth began to be actively raised only at the end of the 14th - beginning of the 20th century. A real breakthrough in science was made in 1839 by Alexander Edmond Becquerel, who managed to become the discoverer of the photovoltaic effect. The study of this topic has increased significantly, and after 44 years, Charles Fritts was able to design the first module in history, which was based on gold-plated selenium. Such use of the energy of the Sun on Earth gave a small amount of released electricity - the total amount of generation then amounted to no more than 1%. Nevertheless, for all mankind, this was a real breakthrough, opening up new horizons of science, which had not even been dreamed of before.

Albert Einstein himself made a significant contribution to the development of solar energy. In the modern world, the name of a scientist is more often associated with his famous theory of relativity, but in fact, he was awarded the Nobel Prize precisely for studying

To this day, the technology of using solar energy on Earth is experiencing either rapid ups or no less rapid falls, but this branch of knowledge is constantly updated with new facts, and we can hope that in the foreseeable future the door to a completely new world will open before us.

Nature is against us

We have already spoken about the advantages of using the energy of the Sun on Earth. Now let's look at the disadvantages. this method, which, unfortunately, is not less.

Due to the direct dependence on geographic location, climatic conditions and the movement of the Sun, the production of solar energy in sufficient quantities requires huge territorial costs. The bottom line is that the larger the area of ​​consumption and processing of solar radiation, the greater the amount of environmentally friendly energy we will receive at the output. The placement of such huge systems requires a large amount of free space, which causes certain difficulties.

Another problem regarding the use of the energy of the Sun on Earth is in direct dependence on the time of day, since the generation at night will be zero, and in the morning and evening it will be extremely insignificant.

An additional risk factor is the weather itself - abrupt shifts conditions can have an extremely negative impact on the operation of this kind of system, since they cause difficulties in debugging the required power. In a sense, situations with a sharp change in the amount of consumption and production can be dangerous.

Clean but expensive

The use of solar energy on Earth is difficult at the moment due to its high cost. The photocells necessary for the implementation of the main processes have a rather high cost. Of course, the positive aspects of using this kind of resource make it pay off, but from an economic point of view, at the moment there is no need to talk about the full payback of cash costs.

However, as the trend shows, the price of solar cells is gradually falling, so over time this problem can be completely resolved.

The inconvenience of the process

The use of the Sun as an energy source is also difficult because this method of processing resources is rather laborious and inconvenient. The consumption and processing of radiation directly depend on the cleanliness of the plates, which is quite problematic to ensure. In addition, the heating of the elements also has an extremely negative effect on the process, which can only be prevented by using the most powerful cooling systems, which requires additional material costs, and considerable ones.

In addition, the plates used in solar collectors, after 30 years of active work, gradually become unusable, and the cost of photocells was mentioned earlier.

environmental issue

Earlier it was said that the use of this kind of resource could save humanity from enough serious problems with the environment in the future. The source of resources and the final product are truly environmentally friendly as much as possible.

Nevertheless, the use of solar energy, the principle of operation of solar collectors is to use special plates with photocells, the manufacture of which requires a lot of toxic substances: lead, arsenic or potassium. Their use itself does not bring harm to the environment, however, given the limited period of their operation, over time, the disposal of plates can become a serious problem.

To limit the negative impact on the environment, manufacturers are gradually moving to thin-film plates, which have a lower cost and less detrimental effect on the environment.

Ways to convert radiation into energy

Films and books about the future of mankind almost always give us approximately the same picture of this process, which, in fact, can differ significantly from reality. There are several ways to convert.

The most common can be called the previously described involvement of photocells.

As an alternative, humanity is actively using solar thermal energy, based on the heating of special surfaces, which allows, with the proper direction of the temperature obtained, to heat water. To simplify this process as much as possible, it can be compared with the tanks that are used for a summer shower in private sector homes.

Another way to use radiation to generate energy is the "solar sail", which can only operate in a system of this kind that converts radiation into

The problem of the lack of generation at night is partially solved by solar balloon power plants, the operation of which continues due to the accumulation of released energy and the duration of the cooling process.

We and solar energy

The energy resources of the sun and wind on Earth are used quite actively, although we often do not notice this. Earlier, the folksy heating of water in an outdoor shower has already been mentioned. In fact, most often solar energy is used for these purposes. However, there are many other examples: in almost every lighting store you can find storage bulbs that can work without electricity even at night thanks to the energy accumulated during the day.

Installations based on photocells are actively used in all kinds of pumping stations and ventilation systems.

Yesterday Today Tomorrow

One of the most important resources for humanity is solar energy, and the prospects for its use are extremely high. This industry is actively funded, expanded and improved. Now solar energy is most developed in the United States, where some regions use it as a full-fledged alternative power source. Also, power plants of this type operate in other countries, while they have long headed for this type of electricity generation, which may soon solve the problem of environmental pollution.

Solar energy is used as a source of both electrical and thermal energy. It is environmentally friendly, and no harmful emissions are generated during its conversion. This one is relatively new way In the mid-2000s, when the EU countries began to introduce a policy of reducing dependence on hydrocarbons in the field of electricity generation, the development of electricity production was rapidly developed. Another goal was to reduce greenhouse gas emissions into the atmosphere. It was during these years that the cost of producing solar panels began to decline, and their efficiency began to increase.

Tropical and subtropical climatic zones are the most favorable, in terms of the length of daylight hours and the flow of sunlight throughout the year. Most favorable in temperate latitudes summer season, and as for the equatorial zone, then in it negative factor is cloudy in the middle of daylight hours.

It can be carried out through an intermediate thermal process or directly through. Photovoltaic stations supply electricity directly to the grid, or serve as a source of autonomous power supply to the consumer. Thermal solar stations are mainly used to generate thermal energy by heating various heat carriers, such as water and air.

As of 2011, all solar power plants in the world produced 61.2 billion kilowatt-hours of electricity, which corresponds to 0.28% of the total global electricity generation. This volume is comparable to half of the generation of electricity at hydroelectric power plants in Russia. Most of the world's photovoltaic capacity is concentrated in a small number of countries: in 2012, 7 leading countries had 80% of the total capacity. The most rapid development of the industry was in Europe, where 68% of the world's installed capacity was concentrated. In the first place is Germany, which accounts (2012) for about 33% of world capacities, followed by Italy, Spain and France.

In 2012, the installed capacity of solar photovoltaic plants worldwide was 100.1 GW, which is less than 2% of the total figure for the global electricity industry. Between 2007 and 2012, this volume increased 10 times.

In China, the USA and Japan, solar energy capacities of 7-10 GW were located. Over the past few years, solar energy has been developing especially rapidly in China, where the total capacity of the country's photovoltaic plants has grown 10 times in 2 years - from 0.8 GW in 2010 to 8.3 GW in 2012. Now Japan and China account for 50% of the global solar energy market. China's intention is to receive 35 GW of electricity from solar installations in 2015. This is due to the ever-increasing demand for energy, as well as the need to fight for the cleanliness of the environment, which suffers from the burning of fossil fuels.

According to forecasts of the Japan Photovoltaic Energy Association, by 2030 the total capacity of solar stations in Japan will reach 100 GW.

India plans to increase, in the medium term, the capacity of solar installations by 10 times, that is, from 2 GW to 20 GW. The cost of solar energy in India has already reached the level of 100 dollars per 1 megawatt, which is comparable to the energy received in the country from imported coal or gas.

Only 30 percent of sub-Saharan Africa has access to. Autonomous solar installations and micro-grids are being developed there. Africa, as a region with a strong mining industry, hopes to obtain an alternative to diesel power plants in this way, as well as a reliable backup source for unreliable electricity networks.

In Russia, the period of formation of solar energy is now underway. The first photovoltaic plant with a capacity of 100 kW, located in the Belgorod region, was launched in 2010. Solar polycrystalline panels for it were purchased at the Ryazan plant of metal-ceramic devices. Since 2014, the construction of a solar power plant with a capacity of 5 MW has begun in the Republic of Altai. Other possible projects in this area are also being considered, including in the Primorsky and Stavropol Territories, as well as in the Chelyabinsk Region.

As for solar thermal energy, according to the Renewable Energy Policy Network for the 21st Century, in 2012 its global installed capacity was 255 GW. Most of this thermal capacity is in China. In the structure of such capacities, the main role is played by stations aimed directly at heating water and air.

Ministry of Education of the Republic of Belarus

educational institution

"Belarusian State Pedagogical University named after Maxim Tank"

Department of General and Theoretical Physics

Coursework in General Physics

Solar energy and prospects for its use

Students of 321 groups

Faculty of Physics

Leshkevich Svetlana Valerievna

Scientific adviser:

Fedorkov Cheslav Mikhailovich

Minsk, 2009

Introduction

1. General information oh sun

2. The sun is a source of energy

2.1 Solar energy research

2.2 The potential of solar energy

3. Use of solar energy

3.1 Passive use of solar energy

3.2 Active use of solar energy

3.2.1 Solar collectors and their types

3.2.2 Solar systems

3.2.3 Solar thermal power plants

3.3 Photovoltaic systems

4. Solar architecture

Conclusion

List of sources used

Introduction

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. IN 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.

1. 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

1. Mass M S ~2*10 23 kg

2. R S ~629 thousand km

3. V \u003d 1.41 * 10 27 m 3, which is almost 1300 thousand times greater than the volume of the Earth,

4. average density 1.41 * 10 3 kg / m 3,

5. luminosity L S \u003d 3.86 * 10 23 kW,

6. effective surface temperature (photosphere) 5780 K,

7. rotation period (synodic) varies from 27 days at the equator to 32 days. at the poles

8. free fall acceleration 274 m / s 2 (with such a huge acceleration of gravity, a person weighing 60 kg would weigh more than 1.5 tons).

Structure of the Sun

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.

Rice. 1 Structure of the Sun

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.

2. 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 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 1.1x10 20 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 10 18) kWh annually. However, only 47% of all energy, or approximately 700 quadrillion (7 x 10 17) 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.

2.1 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 fusion of atomic nuclei can occur only at very high pressure and temperatures over 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 0º C to the boiling point.

2.2 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 indicator is equivalent daily work more than a hundred 100W incandescent bulbs for a whole 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.

3. Use of solar energy

Solar radiation can be converted into useful energy using so-called active and passive solar systems. Passive systems are obtained by designing buildings and selecting building materials in such a way as to maximize the use of solar energy. Solar collectors are active solar systems. Photovoltaic systems are also currently being developed - these are systems that convert solar radiation directly into electricity.

Solar energy is also converted into useful energy indirectly by transforming into other forms of energy, such as biomass, wind or water energy. The energy of the Sun "controls" the weather on Earth. A large proportion of solar radiation is absorbed by the oceans and seas, the water in which heats up, evaporates and falls to the ground in the form of rain, "feeding" hydroelectric power plants. The wind required by wind turbines is formed due to non-uniform heating of the air. Another category of renewable energy sources arising from solar energy is biomass. Green plants absorb sunlight, as a result of photosynthesis, organic substances are formed in them, from which heat and energy can subsequently be obtained. electrical energy. Thus, the energy of wind, water and biomass is a derivative of solar energy.

Energy is the driving force of any production. The fact that man had a large amount of relatively cheap energy at his disposal greatly contributed to industrialization and the development of society.

3.1 Passive use of solar energy

solar energy thermal power plant

Passive solar buildings are those designed to take into account local climatic conditions as much as possible, and where appropriate technologies and materials are used to heat, cool and light the building using solar energy. These include traditional building techniques and materials such as insulation, solid floors, and south-facing windows. Such living quarters can be built in some cases at no additional cost. In other cases, additional costs incurred during construction can be offset by lower energy costs. Passive solar buildings are environmentally friendly, they contribute to the creation of energy independence and an energy balanced future.

In a passive solar system, the building structure itself acts as a collector of solar radiation. This definition fits most of the most simple systems where heat is retained in a building by its walls, ceilings or floors. There are also systems where special elements for heat accumulation are built into the structure of the building (for example, boxes with stones or tanks or bottles filled with water). Such systems are also classified as passive solar.

3.2 Active use of solar energy

Active use of solar energy is carried out with the help of solar collectors and solar systems.

3.2.1 Solar collectors and their types

At the heart of many solar energy systems lies the use of solar collectors. The collector absorbs light energy from the sun and converts it into heat, which is transferred to a coolant (liquid or air) and then used to heat buildings, heat water, generate electricity, dry agricultural products or cook food. Solar collectors can be used in almost all processes that use heat.

The technology of manufacturing solar collectors reached almost the modern level in 1908, when William Bailey of the American "Carnegie Steel Company" invented a collector with a heat-insulated body and copper tubes. This collector was very similar to the modern thermosyphon system. By the end of World War I, Bailey had sold 4,000 of these collectors, and the Florida businessman who bought the patent from him sold almost 60,000 collectors by 1941.

A typical solar collector stores solar energy in modules of tubes and metal plates mounted on the roof of a building, painted black for maximum radiation absorption. They are encased in glass or plastic and tilted to the south to capture maximum sunlight. Thus, the collector is a miniature greenhouse that accumulates heat under a glass panel. Since solar radiation is distributed over the surface, the collector must have a large area.

There are solar collectors various sizes and designs depending on their application. They can provide a household hot water for washing, washing and cooking, or used to pre-heat water for existing water heaters. Currently, the market offers many different models of collectors.

Integrated manifold

The simplest type of solar collector is a "capacitive" or "thermosiphon collector", which received this name because the collector is also a heat storage tank in which a "one-time" portion of water is heated and stored. Such collectors are used to preheat water, which is then heated to the desired temperature in traditional installations, such as gas water heaters. In conditions household preheated water enters the storage tank. This reduces the energy consumption for its subsequent heating. Such a collector is an inexpensive alternative to an active solar water heating system, using no moving parts (pumps), requiring minimal maintenance, with zero operating costs.

Flat collectors

Flat-plate collectors are the most common type of solar collectors used in domestic water heating and heating systems. Typically, this collector is a heat-insulated metal box with a glass or plastic lid, in which a black-colored absorber (absorber) plate is placed. Glazing can be transparent or matte. Flat-plate collectors typically use frosted, light-only, low-iron glass (which lets through much of the sunlight that enters the collector). Sunlight hits the heat-receiving plate, and thanks to the glazing, heat loss is reduced. The bottom and side walls of the collector are covered with a heat-insulating material, which further reduces heat losses.

Flat-plate collectors are divided into liquid and air. Both types of collectors are glazed or unglazed.

Solar tubular vacuum collectors

Traditional simple flat plate solar collectors have been designed for use in regions with warm sunny climates. They drastically lose their effectiveness in bad days- in cold, cloudy and windy weather. Moreover, weather-induced condensation and humidity will cause premature wear of internal materials, which in turn will lead to system degradation and failure. These shortcomings are eliminated by using evacuated collectors.

Vacuum collectors heat domestic water where higher temperature water is needed. Solar radiation passes through the outer glass tube, hits the absorber tube, and is converted into heat. It is transmitted by the fluid flowing through the tube. The collector consists of several rows of parallel glass tubes, to each of which is attached a tubular absorber (instead of an absorber plate in flat-plate collectors) with a selective coating. The heated liquid circulates through the heat exchanger and gives off heat to the water contained in the storage tank.

The vacuum in the glass tube is the best possible thermal insulation for the collector - reduces heat loss and protects the absorber and heat pipe from adverse external influences. The result is excellent performance that surpasses any other type of solar collector.

Focusing Collectors

Focusing collectors (concentrators) use mirror surfaces to concentrate solar energy on an absorber, also called a "heat sink". The temperature they reach is much higher than flat-plate collectors, but they can only concentrate direct solar radiation, resulting in poor performance in foggy or cloudy weather. The mirror surface focuses sunlight reflected from a large surface onto a smaller surface of the absorber, thereby achieving a high temperature. In some models, solar radiation is concentrated at a focal point, while in others, the sun's rays are concentrated along a thin focal line. The receiver is located at the focal point or along the focal line. The heat transfer fluid passes through the receiver and absorbs heat. Such collectors-concentrators are most suitable for regions with high insolation - close to the equator and in desert areas.

There are other inexpensive technologically simple solar collectors for a narrow purpose - solar ovens (for cooking) and solar distillers, which allow you to get distilled water cheaply from almost any source.

solar ovens

They are cheap and easy to make. They consist of a spacious, well-insulated box lined with reflective material (such as foil), covered with glass and equipped with an external reflector. The black pan serves as an absorbent, heating up faster than regular aluminum or stainless steel cookware. Solar ovens can be used to disinfect water by bringing it to a boil.

There are box and mirror (with a reflector) solar ovens.

solar distillers

Solar stills provide cheap distilled water, even salty or heavily polluted water can be used as a source. They are based on the principle of evaporation of water from an open container. The solar distiller uses the sun's energy to speed up this process. It consists of a dark-colored heat-insulated container with glazing, which is tilted so that the condensed fresh water flows into a special container. A small solar distiller - about the size of a kitchen stove - can produce up to ten liters of distilled water on a sunny day.

3.2.2 Solar systems

Solar hot water systems

Hot water is the most common type of direct application of solar energy. A typical installation consists of one or more collectors in which the liquid is heated by the sun, as well as a storage tank for hot water heated by the heat transfer fluid. Even in regions with relatively little solar radiation, such as Northern Europe, a solar system can provide 50-70% of the hot water demand. It is impossible to get more, except perhaps with the help of seasonal regulation. In Southern Europe, a solar collector can provide 70-90% of the hot water consumed. Heating water with the help of solar energy is a very practical and economical way. While photovoltaic systems achieve 10-15% efficiency, thermal solar systems show 50-90% efficiency. In combination with wood-burning stoves, domestic hot water demand can be met almost all year round without the use of fossil fuels.

Thermosiphon solar systems

Solar water heating systems with natural circulation (convection) of the coolant, which are used in warm winter conditions (in the absence of frost), are called thermosyphon. In general, these are not the most efficient of solar energy systems, but they have many advantages in terms of housing construction. Thermosyphon circulation of the coolant occurs due to a change in the density of water with a change in its temperature. The thermosyphon system is divided into three main parts:

flat collector (absorber);

pipelines;

· Storage tank for hot water (boiler).

When the water in the collector (usually flat) is heated, it rises up the riser and enters the storage tank; in its place, cold water enters the collector from the bottom of the storage tank. Therefore, it is necessary to locate the collector below the storage tank and insulate the connecting pipes.

Such installations are popular in subtropical and tropical areas.

Solar water heating systems

Most often used for heating pools. Although the cost of such an installation varies depending on the size of the pool and other specific conditions, if solar systems are installed to reduce or eliminate fuel or electricity consumption, they will pay for themselves in two to four years in energy savings. Moreover, pool heating allows you to extend the swimming season for several weeks at no additional cost.

In most buildings, it is not difficult to arrange a solar heater for the pool. It can be reduced to a simple black hose through which water is supplied to the pool. For outdoor pools, you only need to install an absorber. Indoor pools require the installation of standard manifolds to provide warm water in the winter as well.

Seasonal heat storage

There are also installations that allow using the heat accumulated in the summer by solar collectors and stored with the help of large storage tanks (seasonal storage) in winter. The problem here is that the amount of liquid needed to heat a house is comparable to the volume of the house itself. In addition, the heat storage must be very well insulated. In order for a conventional domestic storage tank to retain most of the heat for half a year, it would have to be wrapped in a layer of insulation 4 meters thick. Therefore, it is advantageous to make the storage capacity very large. As a result, the ratio of surface area to volume decreases.

Large solar district heating installations are used in Denmark, Sweden, Switzerland, France and the USA. Solar modules are installed directly on the ground. Without storage, such a solar heating installation can cover about 5% of the annual heat demand, since the installation should not generate more than minimal amount consumed heat, including losses in the district heating system (up to 20% during transmission). If there is daytime heat storage at night, then a solar heating installation can cover 10-12% of the heat demand, including transmission losses, and with seasonal heat storage, up to 100%. There is also the possibility of combining district heating with individual solar collectors. The district heating system can be switched off for the summer when the hot water supply is provided by the Sun and there is no demand for heating.

Solar energy combined with other renewable sources.

A good result is the combination of various renewable energy sources, for example, solar heat combined with seasonal heat storage in the form of biomass. Or, if the remaining energy demand is very low, liquid or gaseous biofuels can be used in combination with efficient boilers in addition to solar heating.

An interesting combination is solar heating and solid biomass boilers. This also solves the problem seasonal storage solar energy. The use of biomass in summer is not the optimal solution, since the efficiency of boilers at partial load is low, in addition, losses in pipes are relatively high - and in small systems, burning wood in summer can be inconvenient. In such cases, all 100% of the heat load in summer can be provided by solar heating. In winter, when the amount of solar energy is negligible, almost all heat is generated by burning biomass.

There is a lot of experience in Central Europe in combining solar heating and biomass combustion for heat production. Typically, about 20-30% of the total heat load is covered by the solar system, and the main load (70-80%) is provided by biomass. This combination can be used both in individual residential buildings and in central (district) heating systems. In the conditions of Central Europe, about 10 m 3 of biomass (eg firewood) is enough to heat a private house, and a solar installation helps to save up to 3 m 3 of firewood per year.

3.2.3 Solar thermal power plants

In addition to the direct use of solar heat, in regions with high level solar radiation, it can be used to produce steam, which rotates a turbine and generates electricity. The production of solar thermal electricity on a large scale is quite competitive. The industrial application of this technology dates back to the 1980s; since then, the industry has developed rapidly. More than 400 megawatts of solar thermal power plants have already been installed by US utilities, providing electricity to 350,000 people and displacing the equivalent of 2.3 million barrels of oil per year. Nine power plants located in the Mojave Desert (in the US state of California) have 354 MW of installed capacity and have accumulated 100 years of industrial operation experience. This technology is so advanced that, according to official information, it can compete with traditional power generation technologies in many parts of the United States. In other regions of the world, projects to use solar heat to generate electricity should also be launched soon. India, Egypt, Morocco and Mexico are developing corresponding programs, grants for their financing are provided by the Global Environment Facility (GEF). In Greece, Spain and the US, new projects are being developed by independent electricity producers.

According to the method of heat production, solar thermal power plants are divided into solar concentrators (mirrors) and solar ponds.

solar concentrators

Such power plants concentrate solar energy using lenses and reflectors. Since this heat can be stored, such stations can generate electricity as needed, day or night, in any weather.

Large mirrors - with point or line focus - concentrate Sun rays to such an extent that the water turns into steam, while releasing enough energy to turn the turbine. Luz Corp. installed huge fields of such mirrors in the Californian desert. They produce 354 MW of electricity. These systems can convert solar energy into electricity with an efficiency of about 15%.

Exist the following types solar concentrators:

1. Solar parabolic concentrators

2. Dish type solar installation

3. Solar power towers with a central receiver.

solar ponds

Neither focusing mirrors nor solar cells can generate power at night. For this purpose, solar energy accumulated during the day must be stored in heat storage tanks. This process naturally occurs in the so-called solar ponds.

Solar ponds have a high salt concentration in the bottom water layers, a non-convective middle layer of water in which the salt concentration increases with depth, and a convective layer with a low salt concentration on the surface. Sunlight falls on the surface of the pond, and heat is retained in the lower layers of the water due to the high concentration of salt. High salinity water, heated by solar energy absorbed by the bottom of the pond, cannot rise due to its high density. It remains at the bottom of the pond, gradually heating up until it almost boils (while the upper layers of water remain relatively cold). The hot bottom "brine" is used day or night as a heat source, thanks to which a special organic coolant turbine can generate electricity. The middle layer of the solar pond acts as thermal insulation, preventing convection and heat loss from the bottom to the surface. The temperature difference between the bottom and the surface of the pond water is sufficient to drive the generator. The coolant, passed through the pipes through the lower layer of water, is fed further into the closed Rankin system, in which a turbine rotates to produce electricity.

3.3 Photovoltaic systems

Devices for the direct conversion of light or solar energy into electricity are called photocells (in English Photovoltaics, from the Greek photos - light and the name of the unit of electromotive force - volt). The conversion of sunlight into electricity takes place in solar cells made of a semiconductor material such as silicon, which, when exposed to sunlight, generate an electric current. By connecting photovoltaic cells into modules, and those, in turn, with each other, it is possible to build large photovoltaic stations. The largest such station to date is the 5-megawatt Carris Plain installation in the US state of California. The efficiency of photovoltaic installations is currently around 10%, however, individual photovoltaic cells can reach an efficiency of 20% or more.

Solar photovoltaic systems are easy to handle and do not have moving mechanisms, but the photovoltaic cells themselves contain complex semiconductor devices similar to those used for the production of integrated circuits. Photovoltaic cells are based on the physical principle that an electric current is generated by the action of light between two semiconductors with different electrical properties that are in contact with each other. The combination of such elements forms a photovoltaic panel or module. Photovoltaic modules, thanks to their electrical properties produce direct current, not alternating current. It is used in many simple battery powered devices. Alternating current, on the other hand, changes its direction at regular intervals. It is this type of electricity supplied by energy producers, it is used for most modern appliances and electronic devices. In the simplest systems, direct current from photovoltaic modules is used directly. In the same place where AC is needed, an inverter must be added to the system, which converts DC to AC.

In the coming decades, a significant part of the world's population will become familiar with photovoltaic systems. Thanks to them, the traditional need for the construction of large, expensive power plants and distribution systems will disappear. As the cost of solar cells declines and technology improves, several potentially huge markets for solar cells will open up. For example, solar cells built into building materials will carry out ventilation and lighting of houses. Consumer products - from hand tools to automobiles - will benefit from the use of components containing photovoltaic components. Utilities will also be able to find new ways to use photovoltaic cells to meet the needs of the population.

The simplest photovoltaic systems include:

· solar pumps - photovoltaic pumping units are a welcome alternative to diesel generators and hand pumps. They pump water exactly when it is most needed - on a clear sunny day. Solar pumps are easy to install and operate. A small pump can be installed by one person in a couple of hours, and neither experience nor special equipment is needed for this.

· Battery photovoltaic systems - the battery is charged by a solar generator, stores energy and makes it available at any time. Even under the most adverse conditions and in remote locations, photovoltaic energy stored in batteries can power necessary equipment. Thanks to the accumulation of electricity, photovoltaic systems provide a reliable source of power day and night, in any weather. Battery-powered photovoltaic systems power lighting, sensors, sound recording equipment, household appliances, telephones, televisions and power tools around the world.

photovoltaic systems with generators - when electricity is needed continuously or there are periods when it is needed more than a photovoltaic array alone can produce, it can be effectively supplemented by a generator. During the daytime, photovoltaic modules meet the daily energy requirement and charge the battery. When the battery is discharged, the motor-generator turns on and runs until the batteries are recharged. In some systems, the generator makes up for the lack of energy when the electricity demand exceeds the total capacity of the batteries. The engine-generator generates electricity at any time of the day. As such, it provides an excellent back-up power source for night or stormy day backup of photovoltaic modules dependent on the whims of the weather. On the other hand, the photovoltaic module operates silently, requires no maintenance and does not emit pollutants into the atmosphere. The combined use of photovoltaic cells and generators can reduce the initial cost of the system. If there is no backup installation, the PV modules and batteries must be large enough to provide power at night.

· Grid-attached photovoltaic systems - in a centralized power supply environment, a grid-connected photovoltaic system can provide part of the required load, while the other part comes from the grid. In this case, the battery is not used. Thousands of homeowners in different countries world use such systems. Photovoltaic energy is either used locally or fed into the grid. When the owner of the system needs more electricity than it generates - for example, in the evening, then the increased demand is automatically satisfied by the network. When the system generates more electricity than the household can consume, the surplus is sent (sold) to the grid. Thus, the utility network acts as a reserve for a photovoltaic system, like a battery for an off-grid installation.

· industrial photovoltaic installations - photovoltaic plants operate silently, do not consume fossil fuels and do not pollute the air and water. Unfortunately, photovoltaic stations are not yet very dynamically included in the arsenal of utility networks, which can be explained by their features. With the current method of calculating the cost of energy, solar electricity is still significantly more expensive than the production of traditional power plants. In addition, photovoltaic systems generate energy only during daylight hours, and their performance depends on the weather.

4. Solar architecture

There are several main ways to passively use solar energy in architecture. Using them, you can create many different schemes, thereby obtaining a variety of building designs. Priorities in the construction of a building with passive use of solar energy are: good location of the house; a large number of windows facing south (in the Northern Hemisphere) to let in more sunlight in winter (and vice versa, a small number of windows facing east or west to limit unwanted sunlight in winter summer time); correct calculation of the heat load on the interior to avoid unwanted temperature fluctuations and keep warm at night, well-insulated building structure.

The location, insulation, orientation of windows and the thermal load on the premises must be a single system. To reduce fluctuations internal temperature insulation must be placed on the outside of the building. However, in places with rapid internal heating, where little insulation is required, or where the heat capacity is low, the insulation should be inside. Then the design of the building will be optimal for any microclimate. It is worth noting the fact that the right balance between the thermal load on the premises and insulation leads not only to energy savings, but also to saving building materials. Passive Solar Buildings - perfect place for life. Here you feel the connection with nature more fully, in such a house there is a lot of natural light, it saves electricity.

Passive use of sunlight provides approximately 15% of the space heating demand in a typical building and is an important source of energy savings. When designing a building, it is necessary to take into account the principles of passive solar construction in order to maximize the use of solar energy. These principles can be applied everywhere and at virtually no additional cost.

During the design of a building, the use of active solar systems such as solar collectors and photovoltaic arrays should also be considered. This equipment is installed on the south side of the building. To maximize the amount of heat in winter, solar collectors in Europe and North America must be installed with an inclination angle of more than 50° from the horizontal plane. Stationary photovoltaic arrays receive within a year the largest number solar radiation, when the angle of inclination relative to the horizon level is equal to the geographic latitude at which the building is located. The slope of the roof of the building and its orientation to the south are important aspects when designing a building. Solar collectors for hot water supply and photovoltaic panels should be located in close proximity to the place of energy consumption. It is important to remember that the proximity of the bathroom and kitchen allows you to save on the installation of active solar systems (in this case, you can use one solar collector for two rooms) and minimize energy losses for transportation. The main criterion for choosing equipment is its efficiency.

Conclusion

Currently, only a negligible part of solar energy is used due to the fact that existing solar panels have a relatively low efficiency and are very expensive to manufacture. However, one should not immediately abandon the practically inexhaustible source of clean energy: according to experts, solar energy alone could cover all conceivable energy needs of mankind for thousands of years to come. It is also possible to increase the efficiency of solar installations by several times, and by placing them on the roofs of houses and next to them, we will provide heating for housing, heating water and the operation of household electrical appliances even in temperate latitudes, not to mention the tropics. For the needs of industry that require large amounts of energy, you can use kilometer-long wastelands and deserts, completely lined with powerful solar installations. But solar energy faces many difficulties with the construction, placement and operation of solar power plants on thousands of square kilometers of the earth's surface. Therefore, the overall share of solar energy has been and will remain quite modest, at least for the foreseeable future.

At present, new space projects are being developed with the aim of studying the Sun, observations are being carried out, in which dozens of countries take part. Data on the processes occurring on the Sun are obtained using equipment installed on artificial Earth satellites and space rockets, on mountain peaks and in the depths of the oceans.

Much attention should also be paid to the fact that energy production, which is a necessary means for the existence and development of mankind, has an impact on nature and the human environment. On the one hand, heat and electricity have become so firmly established in the life and production activities of a person that a person cannot even imagine his existence without it and consumes inexhaustible resources for granted. On the other hand, people are increasingly focusing their attention on the economic aspect of energy and require environmentally friendly energy production. This indicates the need to address a set of issues, including the redistribution of funds to meet the needs of mankind, the practical use of achievements in the national economy, the search and development of new alternative technologies for generating heat and electricity, etc.

Now scientists are investigating the nature of the Sun, finding out its influence on the Earth, and working on the problem of using the almost inexhaustible solar energy.

List of sources used

Literature

1. The search for life in the solar system: Translation from English. M.: Mir, 1988, p. 44-57

2. Zhukov G.F. General theory of energy.//M: 1995., p. 11-25

3. Dementiev B.A. Nuclear power reactors. M., 1984, p. 106-111

4. Thermal and nuclear power plants. Directory. Book. 3. M., 1985, p. 69-93

5. Encyclopedic dictionary of a young astronomer, M.: Pedagogy, 1980, p. 11-23

6. Vidyapin V.I., Zhuravleva G.P. Physics. General theory.//M: 2005, p. 166-174

7. Dagaev M. M. Astrophysics.// M: 1987, p. 55-61

8. Timoshkin S. E. Solar energy and solar batteries. M., 1966, p. 163-194

9. Illarionov A. G. The nature of energy.//M: 1975., p. 98-105

Websites

1. http://www.stroyca.ru

2. http://www.astro.alfaspace.net

3. http://www. solbat.narod.ru/1.htm

4.http://www. sunenergy.4hs.ru

5. http://solar-battery.narod.ru