CC BY
0INFLUENCE OF ATMOSPHERIC POLLUTION ON THE PARAMETRES OF PHOTOVOLTAIC MODULES IN THE SOUTHERN REGIONS OF UZBEKISTAN
B.A. Yuldoshov
Termiz State University https://doi.org/10.5281/zenodo.10803846
Abstract. During the study, the degree of surface contamination of a silicon photovoltaic module (PV) was studied for one month. In the conditions of the city of Termez, the change in short-circuit currents of two identical PVs under the influence of day and night dusting of their surfaces was analyzed. During the presence of the Afghan wind, the degree of pollution of the PV surface was determined and relevant scientific and important practical conclusions were drawn.
Keywords: photovoltaic module, short circuit current, atmospheric air, pollution degree, Afghan wind.
Introduction
The southern regions of Uzbekistan, including the Surkhandarya region, have different climatic conditions than other places: very dry air, hot climatic conditions, periodic Afghan wind and dust. In winter, the temperature rises from February and begins to drop in autumn in November. A certain part of the territory is surrounded by desert and mountains. In such arid climatic conditions, the wind causes an increase in the amount of dust in the atmosphere [1]. The short circuit current of semiconductor solar cells depends on the amount of sunlight absorbed by the crystal lattice of the cell. Therefore, dust collecting on the surface reduces the efficiency of the
Fig. 1 shows an experimental setup for determining the degree of dusting of the PV surface.
Fig. 1. An image of the PVs installation for the experiment. 1 — PV whose surface opens only at night, 2 — PV whose surface is always open, 3 — cover.
PV.
To ensure maximum contamination of PVs, they are placed horizontally. The first PV surface is closed during the day and open at night (from 7:00 p.m. to sunrise until 7:00 a.m.). Unlike the first, the second PV surface is always open day and night.
PV parameters were measured each day when the sun reached the zenith. In this case, the amount of solar radiation falling on the PV surface is almost the same, and measurement errors are minimal. The measurements were taken on sunny days with minimal changes in wind speed (Afghan wind did not blow) and air humidity.
The degree of pollution of the PV surface was determined according to the following formula:
y = -100% (1)
1o
here, y is the degree of pollution, Io is the initial value of PV short-circuit current, i.e. before pollution, In is the value of PV short-circuit current after n days [2].
Fig. 2 shows the results of the study conducted in June 2021, i.e., the time dependence of the two PV pollution degrees.
June
Fig. 2. Time dependence of PV surface contamination degree
During the experiments, the degree of contamination was ~23% for the FEB whose surface was always open, and ~16% for the FEB whose surface was exposed only at night. The reason for this is that when the temperature is high, dust particles, like gas molecules, are in thermal motion. The mean square speed of gas particles at high temperature is proportional to temperature [3].
A high mean square speed causes a large kinetic energy of the particle. As a result, they are less likely to be attracted to the earth. When the temperature decreases, the decrease in kinetic energy causes an increase in the potential energy of the particles. In this case, dust particles combine with water vapor. Therefore, at night due to the heaviness of dust particles, it is pulled down - to the PV surface.
Methods and materials
During the analysis of the above experimental results, the influence of PV surface dusting on PV short-circuit current on normal days and days with Afghan wind was studied. For this, the total short-circuit current of PVs was taken as the total of the short-circuit currents of both PVs open during the day and open at night.
ltotal ~ 1day ^ 1 night (2)
After a certain period of time, the amount of dust on the surface of PVs, that is, due to the increase in the degree of contamination, the short-circuit currents decrease from the initial value. The table below shows the changes in PV pollution degrees and short-circuit currents in one month.
Table 1
Variations in pollution degrees and short-circuit currents of PVs
Days PV whose during the day surface opens PV whose only at night surface opens Change in total short-circuit current
Pollution degree Change in short circuit current Pollution degree Change in short circuit current
1 0 2,990 0 2,99 5,98
2 1,003344 2,960 1,672241 2,94 5,9
3 2,006689 2,930 3,344482 2,89 5,82
4 3,010033 2,900 5,016722 2,84 5,74
5 4,013378 2,870 6,688963 2,79 5,66
6 5,016722 2,840 8,026756 2,75 5,59
7 6,020067 2,810 9,364548 2,71 5,52
8 6,688963 2,790 10,70234 2,67 5,46
9 Afghan wind blew
10 8,026756 2,750 13,37793 2,59 5,34
11 8,695652 2,730 14,71572 2,55 5,28
12 9,364548 2,710 15,71906 2,52 5,23
13 10,03344 2,690 17,05686 2,48 5,17
14 10,70234 2,670 18,39465 2,44 5,11
15 11,37124 2,650 19,39799 2,41 5,06
16 12,04013 2,630 20,40134 2,38 5,01
17 12,70903 2,610 21,40468 2,35 4,96
18 13,37793 2,590 22,40803 2,32 4,91
19 14,04682 2,570 23,41137 2,29 4,86
20 14,71572 2,550 24,41472 2,26 4,81
21 15,05017 2,540 25,41806 2,23 4,77
22 Afghan wind blew
23 15,55184 2,525 27,0903 2,18 4,705
24 15,71906 2,520 27,7592 2,16 4,68
25 15,88629 2,515 28,42809 2,14 4,655
26 16,05351 2,510 29,09699 2,12 4,63
27 16,22074 2,505 29,76589 2,10 4,605
28 16,38796 2,500 30,43478 2,08 4,58
29 16,55518 2,495 32,44147 2,02 4,515
30 16,72241 2,490 33,11037 2,00 4,49
Results and Discussion. From Table 1, it can be seen that the short-circuit current of the PV open during the day decreases by 1.2 times and that of the PV open at night by 1.5 times as a
result of the increase in the degree of pollution of PVs during one month. Therefore, the change in the short-circuit current of PVs under the influence of pollination in one month can be written as follows.
1total = 1 ^1day + 1 1 night (3)
(3) the coefficients in terms of equality are slightly different for days with Afghan wind.
The Afghan wind is a hot, dry, and dusty southwesterly wind that invades the southern regions of Uzbekistan, especially the city of Termez. The local people called it the "Afghan wind" because the wind blows in the south-west direction from Afghanistan. With the approach of the Afghan wind, eddies and vortices are formed, then a dust storm with a speed of 20 m/s and more is formed [4].
Fig. 3 shows the average wind speed in June 2023, according to the information provided
by the hydrometeorological center of Surkhandarya region. 22 "i
20 1816-■
S 14-
^ 12
^ 12
K
10£ 86
42
0
"I—1—1—1—1—Г
5 10 15 20 25 30
Июнь (2023)
Fig. 3. Average daily wind speed in Termez city in June 2023
One month's data shows that the average wind speed in Termez for June is 10 m/s. However, on June 9 and June 22, the wind speed was 21 m/s and 19 m/s respectively. These numbers indicate that the Afghan wind was blowing on these dates. In particular, the data presented in Fig. 4 confirm that the degree of atmospheric air pollution was high on these dates.
Fig. 5 shows hourly indicators of atmospheric air pollution in June. It can be seen from the graph that the average value of air pollution on June 9 and 22 was higher than usual and was 4196 p,g/m3 and 2489 p,g/m3, respectively [5].
Information on the degree of atmospheric pollution was obtained from the automatic monitoring station of atmospheric air pollution installed in the city of Termez within the framework of the project implemented in cooperation with the international public fund "Zamin" and the Hydrometeorological Service Agency (Fig. 6).
4000 -
3500 -
O 3000
I
S 2500
2000
^ 1500
is
1000 -
500
5
20
25
10 15
June (2023)
Fig. 4. Average daily values of atmospheric pollution
30
0
7000'
6000 -
-C 5000 ■
^ 4000'
„S 3000 -
^ 2000 -
1000'
^ ^
<sv fr & & v?' \v <>' <>' ^ v?' f' T>' T>' T>'
June (2023)
Fig. 5. Hourly average values of air pollution degree
0
Fig. 6. Automatic air pollution monitoring station installed in the city of Termez The automatic air pollution monitoring station is equipped with air particle analyzers APMA 370 and APDA-372, these devices record the mass of polluting particles in 1 cubic meter of air in units of p,g/m3. Atmospheric air pollution and PV surface pollution degree are related to each other. Because the degree of atmospheric air pollution is high, the amount of dust settling on the PV surface is also high. In order to determine how equation (3) changes for the days when the Afghan wind blows, it is necessary to tabulate the numerical values of the diagram in Fig. 4.
Table 2
Variations in pollution degrees and short-circuit currents of PVs
June Atmospheric air pollution degree, pg/m3 June Atmospheric air pollution degree, pg/m3
On normal days On the days when the Afghan wind blows On normal days On the days when the Afghan wind blows
1 207 16 136
2 125 17 154
3 143 18 172
4 129 19 320
5 119 20 158
6 134 21 265
7 144 22 3182
8 174 23 688
9 4178 24 245
10 512 25 659
11 467 26 622
12 246 27 110
13 475 28 114
14 136 29 312
15 140 30 108
Total 3151 4178 4063 3182
Degree of atmospheric air pollution on normal days, p,g/m3 7214
Degree of atmospheric air pollution on days when the Afghan wind blows, p,g/m3 7360
It can be seen from Table 2 that the total of the degree of atmospheric air pollution on normal days is approximately equal to the degree of atmospheric air pollution on days when the Afghan wind blows.
Taking into account that the Afghan wind usually lasts for one night, and assuming that the daytime and nighttime pollination degrees of PVs are equal, equation (3) takes the following form:
Itotal = 1,33AIAfg. w. day + 1,33AIAfg. w.night (4)
That is, equation (4) represents the formation of dust on the surface of the PV on the days when the Afghan wind blows, which is equal to its degree of pollination for one month.
Conclusion
Based on the results obtained in the experiment and the information provided by the hydrometeorological center, it was concluded that it is necessary to cover the surface of PVs on days when the Afghan wind blows.
In order to effectively use PVs in the southern regions, it is advisable to provide additional protection of their external surfaces from dust and periodically (quick) cleaning measures.
REFERENCES
1. Muminov R.A. et al. Study of methods for protecting the surface of photovoltaic batteries from pollution. // Asian Journal of Research, 2020. - № 1-3. - pp. 331-335.
2. Юлдошов Б.А. Исследование методов защиты поверхности фотоэлектрических батарей от загрязнений. // Физика полупроводников и микроэлектроника, 2021. - №2. - С. 64-6 8.
3. D.V. Sivukhin. General physics course. // Thermodynamics and molecular physics. Teacher. 1984. - pp. 245-248.
4. National encyclopedia of Uzbekistan - letter "A". State Scientific Publishing House. 20002006. - p. 803
5. https://hydromet.uz/uz/node/3536
