There are various environmental parameters that affect the performance of photovoltaic solar panels. The amount of sunlight, ambient temperature, wind speed, humidity, shadows, dust, installation height above sea level, etc. are among these environmental parameters. In the following, the effect of six factors that play a key role in the operation of the photovoltaic solar panel and as a result of the solar power plant has been investigated.
The effect of radiation intensity on solar panel performance
The short-circuit current of a photovoltaic solar panel is highly dependent on the amount of photons absorbed by its semiconductor material, which depends on the intensity of sunlight. As the intensity of radiation increases, the production energy of the solar panel increases. But this does not always mean increasing the efficiency of the solar panel; Because with the increase in radiation intensity, the temperature of the solar panel can increase and as a result the energy conversion efficiency remains constant or even decreases.
Although the short-circuit current of the photovoltaic solar panel is largely influenced by the intensity of sunlight, its open-circuit voltage will change to a limited extent.
Effect of ambient temperature on solar panel performance
Temperature is an important determining factor that affects the speed of electrical current through any electrical circuit. Engineers are always trying to invent methods such as designing cooling and water spraying systems to improve the performance of photovoltaic systems in high temperature conditions.
As the temperature of the photovoltaic panel increases to more than 25 degrees Celsius, its open circuit voltage decreases greatly; However, its short-circuit current increases only slightly.
The effect of temperature on photovoltaic solar panel performance is defined by its temperature coefficient. The percentage of the temperature coefficient of a solar panel indicates the amount of change in its output power with an increase or decrease in temperature from the standard test conditions (25 degrees Celsius). For example, if the temperature coefficient for a certain solar panel is -0.5%, its maximum output power will decrease by about 0.5% for every 10°C increase in temperature compared to 25°C.
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The combination of two parameters, the intensity of solar radiation and the high temperature of the surrounding environment can lead to overheating of the solar panel and have the following results:
Reduced performance of the solar panel
Reduction in solar panel energy conversion efficiency
Increased degradation in solar cells
Reducing the lifespan of the solar cell
The effect of environmental shadows on solar panel performance
The occurrence of shadow on the solar panel can be due to the shadow caused by objects close to it such as trees, electric light poles, nearby buildings and many others.
If soft shading is created on the surface of the solar panel, it can reduce its short circuit current. On the other hand, if the shade on the surface of the solar panel is so high that the solar radiation reaches zero (hard shading), two general situations can occur; If this intense shadow covers a part of the solar panels, with the operation of the Bypass Diode to prevent the occurrence of the Hot Spot phenomenon and the exit of the shaded area from the circuit, a decrease in the open circuit voltage of the solar panel will occur. . If hard shading occurs on the entire surface of the panel, the output power of the panel will be zero.
Effect of dust on solar panels performance
Dust is defined as fine powder-like particles with a size of less than 500 micrometers. The effect of dust on the solar panels depends on its distribution on the panel (uniform or partial), the size of the particles and its density, which can lead to a decrease in the efficiency of photovoltaic solar panels.
The amount of dust settling on the surface of the solar panel is fundamentally dependent on the characteristics of the dust (chemical characteristics, size, shape, weight, etc.) and also the environmental conditions of the region (factors related to the construction of the power plant, weather conditions of the region). In desert areas, the occurrence of dust is very high and can reduce the electricity production of photovoltaic solar power plant by 40%. The surface quality and tilt angle of the solar panel, air humidity and wind speed are also among other factors affecting the amount of dust settling on the surface of the solar panel.
Based on experimental studies and comparing the performance of solar panels in a clean and dust-covered state, it has been determined that the accumulation of dust on the surface of the solar panel can reduce both the current and the voltage of the solar panel. Although the reduction in open circuit voltage is very small and negligible compared to the reduction in short circuit current.
Effect of humidity on solar panel performance
Humidity is defined as the amount of water in the air. The relative humidity parameter is often used to show the amount of humidity in the air. Based on the results of several researchers, two scenarios should be considered to evaluate the effect of humidity on solar panel performance. First, the effect of water vapor particles on the sun's rays, and the other is the effect of humidity in case of penetration into the solar panel. As the temperature changes during the day, the relative humidity also changes accordingly. This means that as the temperature increases, the relative humidity of the air increases and as the temperature decreases, its amount also decreases.
When sunlight hits vapor droplets in the air, it can be refracted, reflected, or diffracted. These events reduce the impact of direct radiation on the surface of the solar panels, and as a result, its short circuit current is significantly reduced. However, humidity will not have much effect on the open circuit voltage of the solar panel.
Effect of wind on solar panels performance
Conceptually, it may not be true that solar panels efficiency is directly affected by wind speed; However, it plays a key role in the production of solar panel electricity. When the wind blows, the temperature of the solar cell drops, making the electrons able to carry more energy when transitioning to a higher energy level. A solar panel that is cooled by one degree Celsius has 0.05% more efficiency.
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