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ANALYSIS OF THE DEPENDENCE OF THE PERFORMANCE OF
SILICON SEMICONDUCTORS ON TEMPERATURE
Sanjar Zokirov
Doctoral student, Fergana Politechnic Institute
It is known that the value of the electrical parameters of semiconductor solar
cells is relatively stable at temperatures up to + 40 ° C. According to theoretical
calculations and experimental results, if the temperature of a solar cell exceeds the
relative limit, its electrophysical parameters, including their utility coefficients,
will gradually deteriorate. And when a
certain temperature is reached, these
indicators sharply decrease n times [1]. Due to the relatively warm climate in
Uzbekistan, electrophysical problems of photovoltaic installations can be caused
mainly by overheating of solar cells [2, 3].
Therefore, in the course of our experiment, the temperature of a solar cell
made of a silicon semicrystalline semiconductor was increased from + 25 to + 45
C. As a result, a graph of the dependence of the solar cell efficiency on temperature
was obtained (Fig. 1).
Figure: 1. Graph of the dependence of the efficiency of the photocell on its
temperature
As
can be seen from this graph, an increase in the temperature of the
photovoltaic cell by 1 ° C in the range from + 25 ° C to + 30 ° C led to a decrease
in its efficiency by an average of 0.1% and in the limit from + 30 ° C to + 35 ° С
led to a decrease in its useful coefficient by an average of 0.4%. After the
difference between the start and end temperatures increased by 15 ° C, the
efficiency was almost halved. This means that the dependence of the efficiency of
the photoelectric coefficient on its temperature does not change linearly. This leads
to errors in the theoretical calculation of the utility factor for an arbitrary value of
the solar cell temperature.
In the second experiment, the sun's rays were concentrated on a p hotocell
using a concentrator [4-7]. The change in the intensity of the light flux was carried
170
out by moving the photocell in the focal plane of the reflecting lens. By changing
the value of the resistor connected to the electrical circuit, the freewheel voltage,
short-circuit current and maximum power were determined.
Experimental results obtained at an average temperature of + 27 ° C show
that increasing the intensity of sunlight has no effect on the efficiency as expected.
The efficiency of a solar cell placed in a luminous flux with a higher intensity
decreased faster than under normal conditions (Fig. 3).
Since
the increase in temperature, which negatively affects the
electrophysical parameters of the solar cell, is associated with the action of non -
photoactive radiation incident on its surface, the following stages of the experiment
were carried out with a selective spectrum of sunlight. For this, a special device
was created, consisting of a concentrator and a photothermogenerator, according to
the scheme given in previous works [8, 9].
Figure: 2. The graph of the dependence of the temperature of the solar cell on time
at different intensity of solar radiation
Figure: 3. Graph of efficiency dependence solar cell from time to time at different
intensities of solar radiation
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At the next stages of the experiment, when the non -photoactive rays were
blocked by Peltier thermoelements, a decrease in the heating time (Fig. 2) of the
photocell was observed. But, the results obtained as before, practically did not
change. However, due to the absence of non-photoactive sp ectra, the maximum
temperature did not exceed + 37
0
C. Consequently, during the experiment, the
efficiency was more than 13% (Fig. 3).
It turned out that in a relatively hot climate (Uzbekistan, Fergana), the
performance of a solar cell is stable at temperatures from +25 to +35. The lowes t
performance values for solar cells (made from monocrystalline silicon) were found
to be around 6% and 13%, and the highest around 15% and 16% for typical and
triple density selective illumination over a period of time (up to 3 and 15 minutes)
respectively. The experimental results obtained showed that the efficiency of a
photocell installed inside the protective block in a selective photothermogenerator
increases with increasing beam density and does not deteriorate over time due to
the absence of a temperature factor.
Literature
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