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39Висновки:
Запропонована модель пошуку 3aco6iB негласного отримання шформацп на основi диференщаль-них перетворень. Модель дозволяе знаходити дифе-ренщальний спектр рiшень завдань пошуку радюзакладок. Беручi до уваги то, що процес вияв-лення зaсобiв негласного отримання шформацп е випадковим запропоновано метод обчислювання математичного сподiвaння даного процесу.
Лiтература
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2. Пухов Г.Е. Дифференциальные спектры и модели-К.: Наукова думка,1990.-188с.
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4. Чернецкий В.И. Анализ точности нелинейных систем управления.-М: Машинострое-ние,1968.-246с.
5. Стасюк О.1., Баранов В.Л., Баранов Г.Л., Фролова О.Г. Диференщальш перетворення для комп'ютерного моделювання керуючих систем-К-134 с.
6 Лаптев О.А Формальш математичнi моделi для забезпечення безпеки iнформацiï/ Лаптев О.А., Степаненко В.1., Тихонов Ю.О.//Сучасний захист шформацп №1(37), 2019 , ISSN2409-7292, С 59-64.
7. Laptev A.A. The method of searching for digital means of illegal reception of information in information systems in the working range of Wi-Fi /Laptev A.A., Barabash O.V., Savchenko V.V., Savchenko V.A., Sobchuk V.V. International Journal of Advanced Research in Science, Engineering and Technology. In-diа (ISSN: 2350-0328) 2019. Vol. 6, Issue 7- Р. 1010110105
EVALUATION OF SOLAR PANELS QUALITY AND RESEARCH OF DEGRADATION PROCESSES IN THE CLIMATE CONDITIONS OF UZBEKISTAN
Odamov U.
Scientific and Technical Centre of JSC Uzbekenergo, Ph.D., Tashkent
Komilov M.
doctorant, Gulistan State University, Gulistan
ABSTRACT
The article considers the issues of evaluation of solar panels quality and research of degradation processes in the climate conditions of Uzbekistan. Thermal imaging results are given and the degradation coefficient is determined. Recommendations on the choice of solar panels are given.
Keywords: solar cell, solar panel, silicon, single-crystal, polycrystalline, temperature coefficient, degradation.
Today, around the world, including in Uzbekistan, the issue of the development of alternative energy sources is very relevant. Since, the climatic and natural conditions of Uzbekistan provide ample opportunities for the use and development of solar energy. According to preliminary estimates by experts, the approximate technical potential of solar energy in Uzbekistan is 176.8 million tons of oil equivalent [1].
In this regard, for the development of solar energy, research work was brought to the forefront, since in 2012 the Presidential Decree "On the establishment of the International Solar Energy Institute" was adopted.
Also, a decree of the President of the Republic of Uzbekistan dated March 31, 2013 "On measures to develop alternative energy sources" was adopted, which sets out the main directions for the development of the field of renewable energy (RES) and solar energy for the medium and long term.
Specialists and economists of the country have done serious work to study the prospects for the development of helium photovoltaics in Uzbekistan. As a result of research and calculations, it was found that even with the current level of development of solar technologies, the energy received from the Sun can save almost 180 million tons of oil, which is more than three times the volume of hydrocarbons produced in Uzbekistan. When replacing power plants operating on fossil en-
ergy carriers, 450 million tons of less harmful substances will enter the atmosphere, which will undoubtedly improve the region's ecology.
At the beginning of the second decade of the 21st century, the Republic of Uzbekistan took a number of practical actions to develop solar energy. In 2013-2018 With the participation of foreign capital, projects have been implemented to create mining capacities and factories producing silicon, solar panels, solar concentrators, and several solar power plants (SES) have been built.
In 2014 in a special industrial zone "Angren", participants in the Uz-Shindong Silicon joint venture (Uzbekistan-Republic of Korea) commissioned a plant for the production of technical silicon with a capacity of 56 thousand tons per year. In 2015 in Namangan region, together with Korean specialists, a low-power solar power station (130 kW) was put into operation, operating in test mode. In 2016, in the Bukhara region at the Lukoil company's facility, a 1.2 MW solar power station was launched.
In Uzbekistan, in the medium term, it is planned to build several large solar power plants (100 MW each) in the Namangan region and the Sherabad region of the Surkhandarya region. And also, in the long term (until 2025), in accordance with the Solar Road Map, it is planned to build several solar power plants in the Guzarsky district of Kashkadarya region (100 MW), in
the city of Navoi (combined, 130 MW), at the training ground of the International Solar Institute energy (MISE) in the Kibray district of Tashkent region (combined, 10 MW).In May 2018, the President of the country signed a decree "On additional measures for the implementation of investment projects in the field of renewable energy sources".
In the above paragraphs, it can be seen that solar energy is developing strongly in Uzbekistan, for further development it is necessary to ensure high reliability of
in MTf
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Daily totals: Yearly totals
As can be seen in Figure 1, solar energy can be used in more than 95% of the country. The average value of the total solar weather time in a year exceeds 3000 hours, and the solar radiation power in some areas reaches one kilowatt.
At present, according to published data [3], the most efficient solar cells have a efficiency not exceeding 23%. And the average efficiency indicator ranges from 16% to 18%. Therefore, researchers around the world working in the field of solar photovoltaics are working to free the solar photoconverters from the image of a supplier of expensive electricity.
This article discusses the issues of assessing the quality of solar panels and the study of degradation processes in polycrystalline solar cells in the climatic conditions of Uzbekistan.
The solar panel is a combined photoelectric element that converts the energy of the sun into electric current. According to the technology for the production of solar cells, all solar panels are divided into two large groups: silicon and film.
1. a) Silicon single-crystal (mono-Si) are one silicon crystal. They have a square shape with rounded corners. Color is gray or black to blue (anti-reflective). Direct sunlight is best converted.
b) Silicon polycrystalline (poly-Si) block of silicon crystals interconnected. They have a square shape. Color silver-gray or blue (anti-reflective). The absorption capacity of direct sunlight is worse.
solar batteries, which will increase battery life and reduce the cost of solar energy production.
Since, the main criterion for solar panels is the coefficient of performance (COP). The efficiency of solar panels is variable and depends on several factors. The main one is the intensity and duration of insolation, which, in turn, is determined by weather conditions, the duration of the day and night, that is, the breadth of the terrain. A schematic map characterizing the potential of solar energy in various regions of Uzbekistan is shown in the figure below [2].
c) Silicon, film amorphous occupy an intermediate position, because made of silicon, but in the form of a film. They represent the deposition of a silicon semiconductor on a base. Convenient to use. Within six months or a year, they burn out in the sun, and therefore, their power decreases.
2. Film: a) Based on cadmium telluride, they look like a film that is applied to glass. Mirror dark green or black. Most often used in space and in orbit of the Earth. Toxic: produce harmful cadmium. Sophisticated disposal.
b) Based on CIGS (copper-indium selenide) they have the form of a film in which a semiconductor uses copper-indium selenide. Color from dark gray to black. Corroded.
c) Polymer have the appearance of a very thin film. Cheap in production, do not emit harmful substances.
Based on this, we know that there are three types of solar cells - these are single-crystal, polycrystalline, and thin-film. The latter are still under development, so we will not consider them. Let us dwell on a comparison of the characteristics of single-crystal and polycrys-talline solar cells.
Solar panels are placed in open space, so these parameters will affect their work:
1. Temperature power factor. Under the scorching sun, the solar cells heat up and part of the power of the solar panels is lost. On very hot days, the proportion of
Fig. 1: Solar potential in Uzbekistan, kW * h / kWpeak
power loss is 25%. In the case of single-crystal and pol-ycrystalline solar panels, the temperature power factor reaches -0.45%, that is, there will be a decrease in power by -0.45%, for every degree of temperature increase. The temperature coefficient of power is greatly affected by the quality of the photoconverters;
2. The degree of degradation of LID. The degradation of single crystals of panels occurs faster than polycrystals. A year of operation reduces the power of single-crystal batteries to 3%, and polycrystalline to 2%. Such a decrease in power is observed in the first year of operation of solar panels, in the future this degradation for single crystals will be 0.71%, for polycrys-tal panels 0.67%.
Degradation depends on the quality of the solar cells. For panels of dubious quality, degradation can reach 20% in the first year of operation.
3. Photoelectric sensitivity. Polycrystalline photocells are not so sensitive to reduced lighting, compared with single crystals, but the difference in sensitivity is small and is not a selection criterion for this parameter;
4. The effectiveness of the panels. To produce the same power for polycrystalline panels, more area is needed, that is, the efficiency of polycrystalline solar panels is less than single-crystal. Single crystal life is higher.
Now consider the quality of solar panels. According to the quality of performance, photovoltaic cells can be divided into four quality categories:
The first category is Grad A. These are solar panels of the highest quality - without microcracks, no chips. In appearance, these photocells are completely identical in color and structure. This category has the smallest degradation and highest efficiency.
The second category is Grad B. These photoconverters practically do not differ from the photocells of the first category, but have slight changes in color. But they have greater degradation and shorter life.
The third category is Grad C. The difference from the previous category is the presence of chips and cracks, heterogeneous color, but low cost. For the power supply of a private house, such solar panels should not be used because of low efficiency, high degradation and short life.
Fourth category - Grad D has the lowest quality performance. The structure of these panels is heterogeneous with visible defects. The small size of the solar
cells needs additional soldering, which further degrades the parameters. Such elements have little reliability. They are not recommended to be installed even at a low cost.
The technical characteristics of solar panels include:
• Power of solar panels and sizes;
• Permissible power deviation limits;
• Efficiency of the solar panel;
• Temperature coefficient;
• The life of solar panels.
The performance of solar panels is usually evaluated under standard test conditions (STC): illumination 1000 W/m2, solar spectrum AM 1.5 and module temperature at 25 ° C.
Electrical specifications include rated power (Pmax, measured in W), open circuit voltage (Voc), short circuit current (Isc, measured in amperes), maximum supply voltage (Vmp), maximum current (Imp), peak power, (W-peak, Wp) and module efficiency (%).
Next, we consider the process of degradation of the performance of photovoltaic modules (Potential Induced Degradation), hereinafter abbreviated PID, this is a significant deterioration in the properties of modules over time, reducing efficiency to 95%, is the most undesirable phenomenon for any solar panels. Some types of PID are reversible, some are not, and present a problem for solar panels.
As we know [3], the most famous cause of PID was the polarization seen in the first high-performance panels manufactured by the American company Sun-Power. Under certain conditions, panels lost up to 30% of their rated power in a very short time. As it was found out, the reason was the potential of the panels relative to the ground, and degradation could be prevented by grounding the positive electrode of the solar battery. Such grounding even allowed the restoration of solar panels that were already exposed to the PID effect.
If there is a PID at the element level, this effect also appears at the panel level. This is clearly seen in the current - voltage characteristic (CVC) of the solar module shifts downward (Fig. 2) [4]. As a result, the efficiency of converting light energy into electricity falls.
M_
—
V,B
Fig. 2. Volt-ampere characteristic (VAC)
According to [5], a study of photovoltaic degradation published by the National Renewable Energy Laboratory (NREL), the average solar panel degradation rate is 0.8% per year (up to 80% by 25 years), with the median dropping to 0.5%, and 78% of all installations examined showed a degree of deterioration of less than 1%. However, these are average values, and there are a number of factors that can change this figure, for example, technology.
The degradation of solar panels occurs when the potential difference between the solar module and the mounting structure (usually an aluminum or steel frame) leads to leakage currents that are observed in the layers between the semiconductor wafers and other elements of the module (glass, laminating layer, back sheet, protective frame) Thus, the ability of the module to generate the rated output voltage is lost.
World practical studies have also revealed an increase in the intensity of PID processes with an increase
The temperature of the solar battery is one of the factors affecting the efficient operation of a solar power plant. Studies have shown that the temperature coefficient of open circuit voltage (Voc) is much higher than the temperature coefficient of short circuit current (Isc), and therefore, with increasing temperature, the voltage drop is greater than the increase in current strength. Therefore, the power of the solar battery, as the product of the amperage and voltage, decreases with increasing temperature, and the battery operates with less efficiency.
Also, to assess the impact of real working conditions on the development of the solar module, July 27, 2019 was carried out. Thermal imaging observations with the Testo-880 thermal imager, as shown by the thermo gram of the working solar panel, that the surface temperature of the solar panels ranged from 55-600C, no defects of the solar panels were revealed.
In the study of electricity generation, it was determined that in 2016 the monthly electricity generation was 93,600 kWh, and in 2019 the monthly electricity generation was 93,132 kWh. Based on this, the degradation of these solar panels was found to be about 0,6 % over 4 years.
Thus, to evaluate solar panels, it is necessary to take into account all the factors that affect the change
in environmental humidity. Also, the causes of PID -processes can be divided into four main groups:
• Environmental factors
• Features of the structure of the system
• Module structure
• Photoelectric converter structure
It is clear that it is almost impossible to control the environment, so all the efforts of scientists and engineers are aimed at studying 2, 3 and 4 factors.
Having studied the world experience in the degradation of solar panels, the technical conditions and degradation processes in silicon polycrystalline solar panels that were installed in the Namangan region of Uzbekistan were previously determined. The total capacity of SES is 130 kW.
All installed polycrystalline solar panels belong to the following Korean manufacturers: S-ENERGY Co., Ltd, JSPV Co., Ltd, "Topsun Energy Ltd" "Hanwha SolarOne". The electrical characteristics of solar panels are shown in table 1.
Table 1
in the power of modules in real conditions. Other factors affecting the performance of a solar power plant must be considered. It is necessary to take into account losses in the wires, in the inverter, controller, etc. Also, there is a normal degradation of solar panels over time, as well as a decrease in power due to dust, dirt, excessive heating of the modules or their darkening, different power of the modules in series circuits, etc. The influence of these factors may vary depending on the season of the year, geographical location, installation method, azimuth and inclination of panels, etc.
References
1. UNDP Reports "Prospects for the Development of Renewable Energy in Uzbekistan" (Tashkent, 2007), "Alternative Energy Sources: Possibilities of Use in Uzbekistan" (Tashkent, 2011).
2. World Bank Group, Global Solar Atlas, So-largis, URL: https://solargis.com/maps-and-gis-data/download/uzbekistan/.
3. Raushenbach G. Handbook for the design of solar cells: TRANS. from English - M .: Energoatomiz-dat, 1983
4.http: // pidbull.com/wp-content/up-loads/sites/4/2015/11/pid-detectie1 .png
5. http://www.nrel.gov/
Model name HANWHA YSL250 JSMP250A TS-M400NA1 SM-250PC8
Maximum Power (Pmax) 250 W 250 W 400 W 250 W
Maximum Power Current (Imp) 8,23 A 8,19 A 8,12 A 8,14 A
Maximum Power Voltage (Vmp) 30,4 V 38,2 V 49,27 V 30,8 V
Short-Circuit Current (ISc) 8,78 A 8,65 A 8,62 A 8,67 A
Open-Circuit Voltage (Voc) 37,7 V 30,75 V 61,10 V 37,5 V
Maximum System Voltage 1000 V 1000 V 1000 V 1000 V
Operation Temperature -380C—+870C -40°C—+90°C -37°C^88°C -370C—+890C
Module Efficiency 16,02 % 15,42 % 15,89 % 16,22 %
