How to calculate the amount of solar energy in the region. How much energy does a solar panel give

The intensity of sunlight that reaches the earth varies with time of day, year, location, and weather conditions. The total amount of energy calculated per day or per year is called irradiation (or in another way "the arrival of solar radiation") and shows how powerful the solar radiation was. Irradiation is measured in W*h/m² per day or other period.

The intensity of solar radiation in free space at a distance equal to the average distance between the Earth and the Sun is called the solar constant. Its value is 1353 W / m². When passing through the atmosphere, sunlight is attenuated mainly due to absorption of infrared radiation by water vapor, ultraviolet radiation by ozone, and scattering of radiation by atmospheric dust particles and aerosols. The indicator of atmospheric influence on the intensity of solar radiation reaching the earth's surface is called "air mass" (AM). AM is defined as the secant of the angle between the Sun and the zenith.

Figure 1 shows the spectral distribution of solar radiation intensity under various conditions. The upper curve (AM0) corresponds to the solar spectrum outside the Earth's atmosphere (for example, on board a spacecraft), i.e. at zero air mass. It is approximated by the intensity distribution of black body radiation at a temperature of 5800 K. Curves AM1 and AM2 illustrate the spectral distribution of solar radiation on the Earth's surface when the Sun is at the zenith and at an angle between the Sun and the zenith of 60°, respectively. In this case, the total radiation power is about 925 and 691 W / m², respectively. The average intensity of radiation on Earth approximately coincides with the intensity of radiation at AM=1.5 (the Sun is at an angle of 45° to the horizon).

Near the surface of the Earth, one can take the average value of the intensity of solar radiation as 635 W / m². On a very clear sunny day, this value ranges from 950 W/m² to 1220 W/m². The average value is approximately 1000 W / m². Example: Total radiation intensity in Zurich (47°30′ N, 400 m above sea level) on a surface perpendicular to the radiation: 1 May 12:00 1080 W/m²; 21 December 12:00 930 W/m² .

To simplify the calculation of solar energy, it is usually expressed in hours of sunshine with an intensity of 1000 W/m². Those. 1 hour corresponds to the arrival of solar radiation of 1000 W*h/m². This roughly corresponds to the period when the sun shines in summer in the middle of a sunny cloudless day on a surface perpendicular to the sun's rays.

Example
The bright sun shines with an intensity of 1000 W / m² on a surface perpendicular to the sun's rays. For 1 hour, 1 kWh of energy falls on 1 m² (energy is equal to the product of power and time). Similarly, an average solar input of 5 kWh/m² per day corresponds to 5 peak hours of sunshine per day. Do not confuse peak hours with actual daylight hours. During daylight hours, the sun shines with different intensity, but in total it gives the same amount of energy as if it shone for 5 hours at maximum intensity. It is the peak hours of sunshine that are used in the calculations of solar power plants.

The arrival of solar radiation varies during the day and from place to place, especially in mountainous areas. Irradiation varies on average from 1000 kWh/m² per year for northern European countries, to 2000-2500 kWh/m² per year for deserts. Weather conditions and the declination of the sun (which depends on the latitude of the area) also leads to differences in the arrival of solar radiation.

In Russia, contrary to popular belief, there are a lot of places where it is profitable to convert solar energy into electricity using. Below is a map of solar energy resources in Russia. As you can see, in most of Russia it can be successfully used in seasonal mode, and in areas with more than 2000 hours of sunshine per year - all year round. Naturally, in winter, energy generation by solar panels is significantly reduced, but still the cost of electricity from a solar power plant remains significantly lower than from a diesel or gasoline generator.

It is especially beneficial to use where there are no centralized electrical networks and energy supply is provided by diesel generators. And there are a lot of such regions in Russia.

Moreover, even where there are grids, the use of solar panels operating in parallel with the grid can significantly reduce energy costs. With the current trend of increasing tariffs from Russia's natural energy monopolies, installing solar panels is becoming a smart investment.

4.1.1. Assessment of the gross energy resource (potential) of solar energy

Analysis of factors affecting the value of the gross energy resource of solar energy. The energy of solar radiation falling on the Earth is 10,000 times greater than the amount of energy produced by mankind. The world commercial market buys and sells about 85∙103 billion kWh of energy per year. It is extremely difficult to estimate how much non-commercial energy humanity consumes. Some experts believe that the non-commercial component is close to 20% of all energy used.

Electricity consumption in Russia as a whole in 2015 amounted to 1.036∙103 billion kWh. The Russian Federation has a huge gross resource use of solar energy. The energy of the total annual solar radiation falling on the horizontal surface of the territory of our country is about 20.743∙10 6 billion kWh/year, which exceeds the need for energy by about 20,000 times.

Irradiation of the earth's surface with solar radiation, which has a light, thermal and bactericidal effect, is called insolation.

Insolation is measured by the amount of solar radiation energy falling on a unit of horizontal surface per unit of time.

The flux of solar radiation passing through an area of ​​1 m 2 located perpendicular to the flow radiation at a distance of one astronomical unit from the center of the Sun (that is, outside the Earth's atmosphere), is equal to 1367 W / m 2 - the solar constant.

Due to absorption by the Earth's atmosphere, the maximum solar radiation flux at sea level is 1020 W/m 2 . However, it should be taken into account that the average daily value of the solar radiation flux through a single area is at least three times less (due to the change of day and night and the change in the angle of the sun above the horizon). In winter, in temperate latitudes, this value is two times less. This amount of energy per unit area determines the possibilities of solar energy. The prospects for solar power generation are also diminishing due to global dimming, the man-made reduction in solar radiation reaching the Earth's surface.

The total solar radiation in the Earth's atmosphere consists of direct and scattered radiation . The amount of energy falling per unit area per unit time depends on:

- geographic latitude of the area,

– local climate and time of year,

- density, humidity and degree of pollution of atmospheric air,

– annual and daily motion of the Earth,

- the nature of the earth's surface,

- from the angle of inclination of the surface on which the radiation falls, with respect to the Sun.

The atmosphere absorbs some of the sun's energy. The longer the path of sunlight in the atmosphere, the less direct solar energy reaches the earth's surface. When the Sun is at its zenith (the angle of incidence of the rays is 90 °), its rays hit the Earth in the shortest way and intensively give off their energy to a small area. On Earth, this happens around the equator in the tropics. As you move away from this zone to the south or north, the length of the path of the sun's rays increases and the angle of their incidence on the earth's surface decreases. As a result:

increased energy loss in the air,

solar radiation is distributed over a large area,

reducing the amount of direct energy falling on a unit area, and

increasing the proportion of scattered radiation.

In addition, the length of the day at different times of the year also depends on the latitude of the area, which also determines the amount of solar radiation entering the earth's surface. An important factor determining the potential of solar energy is the duration of solar radiation during the year (Fig. 4.1).

Rice. 4.1. Sunshine duration in Russia, hour/year

For high-latitude territories, where a significant part of the winter time falls on the polar night, the difference in radiation inflow in summer and winter can be quite large. So beyond the Arctic Circle, the duration of sunshine varies from 0 hours in December to 200-300 hours in June and July, with an annual duration of about 1200-1600 hours. In the north of the country, the amount of solar energy reaching the Earth's surface in winter differs from the average annual value by less than 0.8 kWh / (m 2 × day), in summer - by more than 4 kWh / m 2. If in the winter months the levels of solar radiation in the northern and southern regions of Russia are very different, then the summer insolation indicators in these territories due to the long daylight hours in the northern latitudes turn out to be quite comparable. However, due to the lower annual duration of sunshine, the circumpolar territories are inferior in total solar radiation to the regions of the middle zone and the south, respectively, by 1.3 and 1.7 times.

Climatic conditions in a particular area determine the duration and level of cloudiness in the region, humidity and air density. Clouds are the main atmospheric phenomenon that reduces the amount of solar energy reaching the Earth's surface. Their formation is influenced by such features of the local relief as mountains, seas and oceans, as well as large lakes. Therefore, the amount of solar radiation received in these areas and the regions adjacent to them may differ.

The nature of the earth's surface and terrain also affects its reflectivity. The ability of a surface to reflect radiation is called albedo (from Latin - whiteness). It has been established that the albedo of the earth's surface varies over a very wide range. So, the albedo of pure snow is 85-90%, sand - 30-35%, chernozem - 5-14%, green leaves - 20-25%, yellow leaves - 33-39%, water surface at a Sun height of 90 0 - 2 %, the water surface at a Sun height of 20 0 - 78%. Reflected radiation increases the scattered radiation component.

Anthropogenic and natural atmospheric pollution can also limit the amount of solar radiation that can reach the earth's surface. Urban smog, smoke from forest fires and airborne volcanic ash reduce the use of solar energy by increasing the dispersion and absorption of solar radiation. These factors have a greater influence on direct solar radiation than on the total. With severe air pollution, for example, with smog, direct radiation is reduced by 40%, and the total - only by 15-25%. A strong volcanic eruption can reduce, and over a large area of ​​the Earth's surface, direct solar radiation by 20%, and total - by 10% for a period of 6 months to 2 years. With a decrease in the amount of volcanic ash in the atmosphere, the effect weakens, but the process of complete recovery may take several years.

The amount of solar energy incident on the receiving surface also changes when the position of the Sun changes during the day in different months of the year. Usually more solar radiation hits the Earth at noon than early in the morning or late in the evening. At noon, the Sun is high above the horizon, and the length of the path of passage of sunlight through the Earth's atmosphere is reduced. Consequently, less solar radiation is scattered and absorbed, which means more reaches the surface. In addition, the deviation of the angle of incidence of sunlight on the receiving surface from 90 ° leads to a decrease in the amount of energy per unit area - the projection effect. The influence of this effect on the level of insolation can be seen in Figure 4.2.

Rice. 4.2. The effect of changing the angle of incidence of the sun's rays on the value

insolation - projection effect

One stream of solar energy 1 km wide falls on the earth at an angle of 90 °, and another of the same width at an angle of 30 °. Both streams carry the same amount of energy. In this case, an oblique solar beam spreads its energy over an area twice as large as a beam perpendicular to the receiving surface, and, consequently, half as much energy will flow per unit area per unit time.

Earth's surface, absorbing solar radiation (absorbed radiation), heats up and radiates heat into the atmosphere (reflected radiation). The lower layers of the atmosphere largely delay terrestrial radiation. The radiation absorbed by the earth's surface is spent on heating the soil, air, and water.

That part of the total radiation that remains after reflection and thermal radiation of the earth's surface is called radiation balance. The radiation balance of the earth's surface changes during the day and seasons.

Sources of information for assessing the value of the gross resource (potential) of solar energy. The information basis for estimating the value of this gross resource (potential) of solar energy is the measurement data of solar radiation in various regions of the country with the subsequent division of the region into zones with a relatively uniform value of the insolation level. For these purposes, data generated using the results of actinometric observations are needed, i.e. data on the intensity of direct, scattered and total solar radiation, on the radiation balance and the nature of the reflection of radiation from the earth's surface (albedo).

Given the sharp reduction in the number of meteorological stations conducting ground-based actinometric observations in Russia, in 2014, information on the distribution of solar energy resources from the NASA Surface meteorology and Solar Energy (NASA SSE) database was used to estimate the gross potential (resource) of solar energy. This base was formed on the basis of satellite measurements of the radiation balance of the earth's surface, carried out as part of the World Climate Research Program's International Satellite and Cloud Climatology Program (ISCCP) from July 1983 to June 2005. Based on their results, taking into account the nature of the reflection of radiation from the earth's surface, the state of cloudiness, atmospheric pollution by aerosols and other factors, the values ​​of the monthly amounts of solar radiation incident on a horizontal surface were calculated for a 1º × 1º grid covering the entire globe, including the territory of the Russian Federation.

Calculation of the total radiation incident on an inclined surface with a given orientation angle. When assessing the potential, it is necessary to be able to determine the amount of total radiation falling at a certain time on an inclined surface oriented with respect to the earth's surface at an angle of interest to us.

Before proceeding to the description of the methodology for calculating the total radiation, it is necessary to introduce the basic concepts related to the assessment of solar radiation.

The review will take place in horizontal coordinate system. In this system, the origin of coordinates is placed at the observer's location on the earth's surface. The horizontal plane acts as the main plane - the plane mathematical horizon. One coordinate in this system is either sun height α, or his zenith distance z. Another coordinate is azimuth a.

The mathematical horizon is a large circle of the celestial sphere, the plane of which is perpendicular to the plumb line at the point where the observer is located.

The mathematical horizon does not coincide with visible horizon due to the unevenness of the Earth's surface, different heights of observation points, as well as the curvature of light rays in the atmosphere.

Solar zenith angle z is the angle between the sunbeam and the normal to the horizontal plane at observation point A.

Sun altitude angle α is the angle in the vertical plane between the sunbeam and its projection on the horizontal plane. The sum of α+z is 90°.

Azimuth of the Sun a- this is the angle in the horizontal plane between the projection of the sun's beam and the direction to the south.

Surface azimuth a p measured as the angle between the normal to the surface in question and the south direction.

Sun declination angle- this is the angle between the line connecting the centers of the Earth and the Sun, and its projection on the equatorial plane. The declination of the Sun continuously changes throughout the year - from -23 ° 27 "on the day of the winter solstice on December 22 to + 23 ° 27" on the day of the summer solstice on June 22 and is zero on the days of the spring and autumn equinoxes (March 21 and September 23).

Local true solar time is the time determined at the location of the observer by the apparent position of the Sun on the celestial sphere. 12 hours local solar time corresponds to the time when the Sun is at its zenith (highest in the sky).

Local time usually differs from local solar time due to the eccentricity of the earth's orbit, human use of time zones, and artificial time offsets to save energy.

Celestial equator- this is a large circle of the celestial sphere, the plane of which is perpendicular to the axis of the world (the axis of rotation of the earth) and coincides with the plane of the earth's equator.

The celestial equator divides the surface of the celestial sphere into two hemispheres: the northern hemisphere, with a peak at the north celestial pole, and the southern hemisphere, with a peak at the south celestial pole.

sky meridian- a large circle of the celestial sphere, the plane of which passes through a plumb line and the axis of the world (the axis of rotation of the earth).

hour angle- the angular distance measured along the celestial equator to the west from the celestial meridian (that part of it that the sun crosses at the time of the upper climax) to the hour circle passing through a chosen point on the celestial sphere.

The hour angle is the result of converting local solar time into the number of degrees the sun travels across the sky. By definition, the hour angle is zero at noon. Since the Earth rotates 15 0 in one hour (360 o / 24 hours), then for every hour in the afternoon the Sun moves 15 0 . In the morning the angle of the sun is negative, in the evening it is positive.

As background information to calculate the total radiation, the values ​​of the following indicators are used, obtained by statistical processing of observational data:

- the average monthly amount of total solar radiation falling on a horizontal area during the day, ;

is the average monthly amount of scattered (diffuse) solar radiation falling on a horizontal area during the day, ;

– albedo of the earth's surface - the average monthly ratio of the amount of solar radiation reflected by the earth's surface to the amount of total solar radiation incident on the earth's surface (i.e., the fraction of radiation reflected by the earth's surface), share.

All further calculations are carried out for the "average day of the month", i.e. day, in which the angle of declination of the Sun is closest to the mean monthly angle.

Solar radiation on a horizontal surface. Using this information, the values ​​of the total (and scattered () solar radiation incident on horizontal surface behind t-th observation hour:

And - the coefficients of transition from daily to hourly radiation - are determined as follows:

- hour angle in t-th estimated hour of the day, degrees;

- hour angle of sunset (sunset), deg.

hour angle of the sun calculated using the ratio

– time of solar noon, information about which can be found in the NASA Database, hour.

Sunset hour angle rated as

– latitude, degrees;

is the angle of declination of the sun, deg.

Sun declination angle determined by the following formula

– day of the year (from 1 to 365).

Solar radiation on an arbitrarily oriented inclined surface . Calculation hourly total solar radiation, falling on an inclined surface oriented at an angle to the horizon, is produced as follows

is the angle of incidence of direct solar radiation on an inclined surface arbitrarily oriented at an angle to the horizon in t-th hour, degrees;

is the zenith angle of the Sun in t-th hour, degrees;

is the angle of inclination of the surface to the horizon, degrees;

Sun's zenith angle

Angle of incidence straight solar radiation on an inclined surface arbitrarily oriented at an angle to the horizon:

is the azimuthal angle of the Sun in t-th hour of the day, degrees;

is the azimuth of the inclined surface, deg.

The angle of incidence of direct solar radiation on an inclined surface arbitrarily oriented at an angle to the horizon can also be calculated using the following relations:

The relations considered above can be used to estimate the energy potential of the sun with differentiation into hourly (or three-hour) intervals of the day.

Gross electric power resource (potential) of solar energy. To estimate the gross electric power resource of solar energy in our country, the average monthly daily values ​​of the total solar radiation incident on 1 m 2 were used. horizontal plane (kW h / (m 2 ∙ day)). On the basis of this information, with differentiation by the subjects of the federation, the average amount of solar radiation was estimated in million kWh, falling on 1 square kilometer of territory during the year (or in kWh / (m 2 ∙ year)) fig. 4.3.

Rice. 4.3. Distribution of annual solar energy resources on the territory of the Russian Federation with details by federal subjects

On the map, each subject of the federation is assigned its code.

The list of subjects of the federation with their codes with differentiation by federal districts of Russia is presented below. Taking into account the specifics of the assessment of the energy potential of renewable energy sources, the cities of Moscow and St. Petersburg are merged with the Moscow and Leningrad regions, respectively, with the assignment of the united territory of the region code. The subjects of the federation with a large extent from North to South can be divided into parts: North, Center, South.

1. Central Federal District: (31) Belgorod region, (32) Bryansk region, (33) Vladimir region, (36) Voronezh region, (37) Ivanovo region, (40) Kaluga region, (44) Kostroma region, (46) Kursk region, ( 48) Lipetsk region, (50) Moscow region and Moscow, (57) Oryol region, (62) Ryazan region, (67) Smolensk region, (68) Tambov region, (69) Tver region, (71) Tula region, ( 76) Yaroslavl region.

2. Northwestern Federal District: ( 10) Republic of Karelia, (11) Republic of Komi, (29) Arkhangelsk region, (35) Vologda region, (39) Kaliningrad region, (47) Leningrad region and St. Petersburg, (51) Murmansk region, (53) Novgorod region , (60) Pskov region, (83) Nenets Autonomous Okrug.

3. Southern Federal District: ( 1) Republic of Adygea, (8) Republic of Kalmykia, (23) Krasnodar Territory, (30) Astrakhan Region, (34) Volgograd Region, (61) Rostov Region, (91) Republic of Crimea and Sevastopol.

4. North Caucasian Federal District: ( 5) Republic of Dagestan, (6) Republic of Ingushetia, (7) Republic of Kabardino-Balkaria, (9) Republic of Karachay-Cherkessia, (15) Republic of North Ossetia-Alania, (20) Chechen Republic, (26) Stavropol Territory.

5. Volga Federal District: ( 2) Republic of Bashkortostan, (12) Republic of Mari El, (13) Republic of Mordovia, (16) Republic of Tatarstan, (18) Republic of Udmurtia, (21) Republic of Chuvashia, (43) Kirov region, (52) Nizhny Novgorod region, (56) ) Orenburg region, (58) Penza region, (59) Perm region, (63) Samara region, (64) Saratov region, (73) Ulyanovsk region.

6. Ural Federal District: ( 45) Kurgan region, (66) Sverdlovsk region, (72) Tyumen region, (74) Chelyabinsk region, (86) Khanty-Mansiysk Aok-Yugra, (89) Yamal-Nenets Aok.

7. Siberian Federal District: (3) Republic of Buryatia, (4) Republic of Altai, (17) Republic of Tyva, (19) Republic of Khakassia, (22) Altai Territory, (24) Krasnoyarsk Territory (24-1. North, 24-2. Center, 24 -3. South), (38) Irkutsk region (38-1. North, 38-2. South), (42) Kemerovo region, (54) Novosibirsk region, (55) Omsk region, (70) Tomsk region, ( 75) Trans-Baikal Territory.

8. Far Eastern Federal District: ( 14) Republic of Sakha (Yakutia) (14-1. North, 14-2. Center, 14-3. South), (25) Primorsky Territory, (27) Khabarovsk Territory, (27-1. North, 27-2. South), (28) Amur Region, (41) Kamchatka Territory, (49) Magadan Region, (65) Sakhalin Region, (79) Jewish Autonomous Region, (87) Chukotka Autonomous Okrug.

The current opinion that Russia, located mainly in middle and high latitudes, does not have significant solar energy resources for its efficient energy use, is not true. The map below (Fig. 4.4) shows the average annual distribution of solar radiation energy resources over the territory of Russia, which arrives on average per day per 1 platforms of southern orientation with an optimal angle of inclination to the horizon(for each geographic point, this is its own angle at which the total annual solar radiation energy input to a single site is maximum).

Fig.4.4. Distribution of annual average daily solar

radiation across the territory of Russia, kW × hour / (m 2 × day) (optimally

south oriented surface)

Consideration of the presented map shows that within the current borders of Russia, the most "sunny" are not the regions of the North Caucasus, as many assume, but the regions of Primorye and southern Siberia (4.5-5 kWh / (m 2 * day) and above). It is interesting that the well-known Black Sea resorts (Sochi and others), according to the average annual solar radiation input (in terms of natural potential and solar insolation resource) belong to the same zone as most of Siberia, including Yakutia (4.0-4. 5 kW × hour / (m 2 × day)).

For energy-poorly provided areas with decentralized energy supply, it is important that more than 60% of the country's territory, including many northern regions, are characterized by an average annual daily intake of solar radiation from 3.5 to 4.5 kWh / (m 2 × day), which is no different from the south of Germany, which makes extensive use of solar installations.

Analysis of the map shows that in the Russian Federation the highest intensity of insolation from 4.5 to 5.0 kWh / m 2 or more per day is observed in Primorye, in the south of Siberia, in the south of the Republic of Tuva and the Republic of Buryatia, and even beyond the Arctic Circle in the eastern part of Severnaya Zemlya, and not in the southern regions of the country. By solar potential, 4.0 - 4.5 kWh / (m 2 * day), Krasnodar Territory, Rostov Region, southern part of the Volga region, most of Siberia (including Yakutia), southern regions of Novosibirsk, Irkutsk regions, Buryatia, Tyva , Khakassia, Primorsky and Khabarovsk Territories, Amur Region, Sakhalin Island, vast territories from the Krasnoyarsk Territory to Magadan, Severnaya Zemlya, the northeast of the Yamalo-Nenets Autonomous Okrug belong to the same zone as the North Caucasus with famous Russian Black Sea resorts. Nizhny Novgorod, Moscow, St. Petersburg, Salekhard, the eastern part of Chukotka and Kamchatka are characterized by average solar radiation from 2.5 to 3 kWh/m 2 per day. In the rest of the country, the intensity of insolation from 3 to 4 kWh/m 2 per day prevails.

The energy flow has the highest intensity in May, June and July. During this period, in central Russia, per 1 sq. meter of surface accounts for 5 kWh per day. The lowest intensity is in December-January, when 1 sq. meter of surface accounts for 0.7 kWh per day.

Given the current situation, on the map of Ukraine (Fig. 4.3) it is possible to analyze the level of solar radiation in the territory of Crimea.

Rice. 4.3. Distribution of annual incoming solar radiation by

territory of Ukraine, kW × hour / (m 2 × year) (optimally oriented

south facing surface)

Gross thermal energy resource of solar energy. The gross thermal energy resource (potential) sets the maximum amount of thermal energy corresponding to the energy of solar radiation entering the territory of Russia.

Information for evaluating this resource can be insolation in mega- or kilocalories per unit area of ​​the surface receiving radiation per unit time.

Figure 4.4 gives an idea of ​​the distribution of total solar radiation on the horizontal surface of the territory of the Russian Federation in kilocalories per 1 cm2 per year.

Fig.4.4. Distribution of annual incoming solar radiation by

territory of Russia, kcal / (cm 2 × year)

Comprehensive zoning of the territory of Russia according to the potential of solar radiation can be seen in Figure 4.6. 10 zones have been allocated according to the priority of the use potential. Obviously, the southern regions of the European part, the south of Transbaikalia and the Far East have the most favorable conditions for the practical use of solar energy.

Rice. 19. Zoning of the territory of Russia according to the potential of solar

radiation (the number in the circle is the number according to the priority of the potential)

Values ​​of gross energy potentials of solar energy with differentiation by federal districts of the Russian Federation.

When assessing the technical potential of solar power industry, the indicators of the most common (90%) at that time silicon-based photovoltaic cells with an efficiency of 15% were used. The working area of ​​solar installations, taking into account the density of placement of photovoltaic cells in photovoltaic modules, was taken equal to 0.1% of the area of ​​the territory of the region under consideration that is homogeneous in terms of radiation level. The technical potential was calculated in tons of standard fuel as the product of the gross solar potential of the territory by the share of the area occupied by photovoltaic cells and their efficiency.

The definition of the technical heat and power potential of the region is focused on the technical possibilities of converting the energy of solar radiation into thermal energy at the most efficient installations of solar hot water supply. The assessment of the technical potential was carried out on the basis of data on the heat output of such installations in each of the areas with a uniform level of insolation and the assumptions made: on the area occupied by solar collectors equal to 1% of the area of ​​the territory under consideration, the ratio between the areas of thermal and electrical installations - 0.8 and 0 ,2, respectively, and the efficiency of the fuel device is 0.7. Conversion into tons of standard fuel was carried out using a coefficient of 0.34 tce/kWh.

The most objective of the known indicators characterizing the possibility of practical use of solar energy resources is considered to be an indicator of its economic potential. The economic feasibility and scope of the use of electric and thermal solar installations should be determined based on their competitiveness with traditional energy sources. The lack of the required amount of necessary and reliable information was the reason for using simplified methods based on the opinions of qualified experts to assess the magnitude of the economic potential.

In accordance with expert estimates, the economic potential of solar power industry was taken equal to 0.05% of the annual electricity consumption in the region under consideration (according to Rosstat) with its conversion into tons of standard fuel.

With a known intensity of solar radiation, the total energy potential of solar radiation can be calculated in tons of standard fuel, kilowatt-hours, gigacalories. Taking into account the use of photovoltaic cells in solar energy for generating electrical energy and solar collectors for generating heat, the total technical and economic potential is divided into electric power and heat power in accordance with the methodology discussed above (Table 9).

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 the Far East exceed the level of solar radiation in 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 for 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 of SFEU can have a positive impact 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 .

6 http://www.ng.ru/energy/2011-10-11/9_sun_energy.html
7 The organizer is Hevel LLC, the founders of which are the Renova Group of Companies (51%) and the State Corporation Russian Corporation of Nanotechnologies (49%).

A solar battery is a series of solar modules that convert solar energy into electricity and, using electrodes, transmit it further to other converter devices. The latter are needed in order to make alternating current from direct current, which household electrical appliances are able to perceive. Direct current is obtained when solar energy is perceived by photocells and the photon energy is converted into electric current.

How many photons hit the photocell determines how much energy the solar battery provides. For this reason, battery performance is affected not only by the material of the photocell, but also by the number of sunny days per year, the angle of incidence of sunlight on the battery, and other factors beyond human control.

Aspects affecting how much power a solar panel produces

First of all, the performance of solar panels depends on the material of manufacture and production technology. Of those that are on the market, you can find batteries with a performance of 5 to 22%. All solar cells are divided into silicon and film.

Silicon module performance:

• Monocrystalline silicon panels - up to 22%.
• Polycrystalline panels - up to 18%.
• Amorphous (flexible) - up to 5%.

Film module performance:

• Based on cadmium telluride - up to 12%.
• Based on meli-indium-gallium selenide - up to 20%.
• On a polymer basis - up to 5%.

There are also mixed types of panels, which, with the advantages of one type, make it possible to cover the disadvantages of another, thereby increasing the efficiency of the module.

The number of clear days in a year also affects how much energy a solar battery gives. It is known that if the sun in your area appears for a full day on less than 200 days a year, then installing and using solar panels is unlikely to be profitable.

In addition, the efficiency of the panels is also affected by the heating temperature of the battery. So, when heated by 1̊С, the performance drops by 0.5%, respectively, when heated by 10̊С, we have a half reduced efficiency. To prevent such troubles, cooling systems are installed, which also require energy consumption.

To maintain high performance throughout the day, solar tracking systems are installed to help keep the rays on the solar panels at a right angle. But these systems are quite expensive, not to mention the batteries themselves, so not everyone can afford to install them to power their home.

How much energy a solar battery generates also depends on the total area of ​​​​the installed modules, because each photocell can accept a limited amount.

How to calculate how much energy a solar panel provides for your home?

Based on the above points that should be considered when buying solar panels, we can derive a simple formula by which we can calculate how much energy one module will produce.

Let's say you have chosen one of the most productive modules with an area of ​​2 m2. The amount of solar energy on a typical sunny day is approximately 1000 watts per m2. As a result, we get the following formula: solar energy (1000 W / m2) × productivity (20%) × module area (2 m2) = power (400 W).

If you want to calculate how much solar energy is received by a battery in the evening and on a cloudy day, you can use the following formula: the amount of solar energy on a clear day × the sine of the angle of sunlight and the surface of the panel × the percentage of energy converted on a cloudy day = how much solar energy eventually converts the battery. For example, let's say that in the evening the angle of incidence of the rays is 30̊. We get the following calculation: 1000 W / m2 × sin30̊ × 60% = 300 W / m2, and the last number is used as the basis for calculating the power.

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, due to reflection, scattering and absorption by atmospheric gases and aerosols, only 47% of all energy, or approximately 700 quadrillion (7 x 1017) kWh, reaches the Earth's surface.

Solar radiation in the Earth's atmosphere is divided into the so-called direct radiation and scattered by particles of air, dust, water, etc. contained in the atmosphere. Their sum forms the total solar radiation. The amount of energy falling per unit area per unit time depends on a number of factors:

• latitude
• local climate season of the year
• the angle of inclination of the surface with respect to the sun.

Time and geographic location

The amount of solar energy falling on the Earth's surface changes due to the movement of the Sun. These changes depend on the time of day and season. Usually more solar radiation hits the Earth at noon than early in the morning or late in the evening. At noon, the Sun is high above the horizon, and the length of the path of the Sun's rays through the Earth's atmosphere is reduced. Consequently, less solar radiation is scattered and absorbed, which means more reaches the surface.

The amount of solar energy reaching the Earth's surface differs from the average annual value: in winter - less than 0.8 kWh / m2 per day in Northern Europe and more than 4 kWh / m2 per day in summer in this same region. The difference decreases as you get closer to the equator.

The amount of solar energy also depends on the geographical location of the site: the closer to the equator, the greater it is. For example, the average annual total solar radiation incident on a horizontal surface is: in Central Europe, Central Asia and Canada - approximately 1000 kWh/m2; in the Mediterranean - approximately 1700 kWh / m2; in most desert regions of Africa, the Middle East and Australia, approximately 2200 kWh/m2.

Thus, the amount of solar radiation varies significantly depending on the time of year and geographical location (see table). This factor must be taken into account when using solar energy.

	Southern Europe	Central Europe	Northern Europe	Caribbean region
January	2,6	1,7	0,8	5,1
February	3,9	3,2	1,5	5,6
March	4,6	3,6	2,6	6,0
April	5,9	4,7	3,4	6,2
May	6,3	5,3	4,2	6,1
June	6,9	5,9	5,0	5,9
July	7,5	6,0	4,4	6,0
August	6,6	5,3	4,0	6,1
September	5,5	4,4	3,3	5,7
October	4,5	3,3	2,1	5,3
November	3,0	2,1	1,2	5,1
December	2,7	1,7	0,8	4,8
YEAR	5,0	3,9	2,8	5,7

The influence of clouds on solar energy

The amount of solar radiation reaching the Earth's surface depends on various atmospheric phenomena and on the position of the Sun both during the day and throughout the year. Clouds are the main atmospheric phenomenon that determines the amount of solar radiation reaching the Earth's surface. At any point on the Earth, solar radiation reaching the Earth's surface decreases with increasing cloudiness. Consequently, countries with predominantly cloudy weather receive less solar radiation than deserts, where the weather is mostly cloudless.

The formation of clouds is influenced by the presence of local features such as mountains, seas and oceans, as well as large lakes. Therefore, the amount of solar radiation received in these areas and the regions adjacent to them may differ. For example, mountains may receive less solar radiation than adjacent foothills and plains. Winds blowing towards the mountains cause part of the air to rise and, cooling the moisture in the air, form clouds. The amount of solar radiation in coastal areas may also differ from those recorded in areas located inland.

The amount of solar energy received during the day is largely dependent on local atmospheric phenomena. At noon with a clear sky, the total solar

radiation falling on a horizontal surface can reach (for example, in Central Europe) a value of 1000 W/m2 (in very favorable weather conditions this figure can be higher), while in very cloudy weather it is below 100 W/m2 even at noon.

Effects of Atmospheric Pollution on Solar Energy

Anthropogenic and natural phenomena can also limit the amount of solar radiation reaching the Earth's surface. Urban smog, smoke from forest fires and airborne volcanic ash reduce the use of solar energy by increasing the dispersion and absorption of solar radiation. That is, these factors have a greater influence on direct solar radiation than on the total. With severe air pollution, for example, with smog, direct radiation is reduced by 40%, and the total - only by 15-25%. A strong volcanic eruption can reduce, and over a large area of ​​the Earth's surface, direct solar radiation by 20%, and total - by 10% for a period of 6 months to 2 years. With a decrease in the amount of volcanic ash in the atmosphere, the effect weakens, but the process of complete recovery may take several years.

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 1013) 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 1013) 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 amount of solar energy reaching the Earth's surface is many times greater than its consumption, even in countries such as the United States, where energy consumption is huge. If only 1% of the country's territory was used to install solar equipment (photovoltaic panels or solar hot water systems) operating at a 10% efficiency, then the US would be fully supplied with energy. The same can be said about all other developed countries. However, in a certain sense, this is unrealistic - firstly, due to the high cost of photovoltaic systems, and secondly, it is impossible to cover such large areas with solar equipment without harming the ecosystem. But the principle itself is correct.

It is possible to cover the same area by dispersing installations on the roofs of buildings, on houses, along roadsides, on predetermined areas of land, etc. In addition, in many countries already more than 1% of the land is allocated for the extraction, conversion, production and transportation of energy. And, since most of this energy is non-renewable at the scale of human existence, this kind of energy production is much more harmful to the environment than solar systems.