By Admin | 11 November 2022 | 0 Comments
7 Factors Reduce Your Solar Panel Efficiency
Solar energy conversion efficiency is always a big topic for solar panels. But, regardless of the types of solar panels, there are still many factors that will reduce solar panel efficiency.
We all know that the conversion efficiency on solar panels' specification sheet is based on Standard Test Conditions (STC). STC is set on maximum possible solar irradiance (1kW per m2), at the temperature of 25℃ or 77 ℉, and an air mass of 1.5 (related to the thickness of the atmosphere). But the actual outdoor conditions are various. The efficiency would be affected by shading, temperature, panel positioning, accessories loss, etc.
Shading is one of the most important factors that reduce solar panel efficiency. It comes from lots of sources, such as trees and their leaves, buildings, other panels, clouds and more. And the effect of shading is highly variable.
Cells in a solar panel are usually connected in series to get a higher voltage and therefore an appropriate production of electricity. When one solar cell in a panel cell string is shaded, the current is no longer evenly distributed across all the cells. The hot spot effect occurs when the current cannot flow around weak cells. Eventually, the current will concentrate in a few cells, causing them to overheat and possibly melt.
The hot spot effect is one of the most common causes of solar panel failure or fire hazard. Therefore, the use of bypass diodes is critical to ensure that current can flow around weak cells while minimizing the shading effect under various shading conditions.
There is a misconception that high temperatures increase the solar energy output. In contrast, solar cells are sensitive to temperature increases. Higher outdoor temperatures mean that the solar panel's semiconductor material heats up quickly and changes its properties slightly. It causes a slight increase in current but a bigger drop in voltage, which can damage or even degrade the performance of the system. Long-term exposure to high temperatures may also shorten the life of the material.
The maximum power of the solar cells was tested at a STC temperature of 25°C. The actual outdoor working temperature of solar panels is generally higher than 25°C, and the heat dissipation conditions are variable. According to some researches, the loss of temperature affecting solar panel efficiency is 0.5% per degree increase over 25°C. In summer, the temperature easily exceeds 45°C, which may reduce the power output of the solar panel by 10%.
On the other hand, you don't need to worry about cold temperatures, as long as the sun is shining and the solar panels receive unblocked sunlight during the day, they will produce at their estimated efficiency. The only common problem with solar production in winter is that there are far fewer sunny days than in summer, and the solar system produces less electricity per month.
Your solar panel will have the best power output when the solar panel surface is perpendicular to sun light. However, as the sun moves across the sky, so do their angles.
If you want to improve the efficiency, you need to make solar tracking, adjusting the position and angle of the solar panels. In this way you can keep the solar panels always facing the maximum sunlight exposure at the best angle.
The intensity of sunlight variably changes the efficiency of a solar panel throughout the day. The solar panel can produce more energy output approximately in the afternoon when the sun exposure is at its peak.
Cloud cover reduces the amount of sunlight reaching the solar panel, which reduces the efficiency of the solar panel. But this is not something to worry about too much. Although cloud cover reduces the energy efficiency of solar cells, they can still produce energy. It doesn’t cause damage to panels, compared with the tree or building shading.
Solar inverters, charge controllers, and installation wires all affect the performance of a solar system. You should choose quality accessories that are compatible with solar panels. Avoid damaging these accessories as this will reduce output.
You should also consider the cable size to avoid excessive resistance that reduces efficiency. For example, a 220V device will degrade the performance of a 48V solar panel system.
New research from Duke University and the Indian Institute of Technology Gandhinagar shows that pollution can reduce the efficiency of solar panels by up to 25%.
Dust deposited on the surface of the solar panel will firstly reduce the light transmittance of the module surface, and secondly, it will change the incident angle of part of the sun light, resulting in uneven light propagation. So, cleaning solar panels regularly is important.
Also, you should be careful when you set up and store your portable solar panels. A lot of people store their portable solar panels under their beds in RVs. And probably they also put some other appliances on top of the solar panels. When taking the panels out, they do not remove these items first, but directly extract the panels with force. This action will cause the surfaces of the folded solar panels to rub against each other, causing a lot of scratches, affecting the power output. And it may even cause breaking the built-in wires of the solar panels, resulting in the inability to solar energy output.
Many people feedback that their solar panels did not work when they set up the panels after several days of storage. That may be the reason.
Read this article to get tips on how to protect your foldable monocrystalline solar panels.
Due to manufacturing differences, modules of the same type may have slightly different electrical characteristics. This mismatch between modules results in a performance penalty.
Some of these factors cannot be influenced by people, such as weather and temperature, and some of them can be changed, such as regular cleaning, the best installation angle and location. In order to obtain more power output, it’s important to learn more about the relevant knowledge and take proper action.
We all know that the conversion efficiency on solar panels' specification sheet is based on Standard Test Conditions (STC). STC is set on maximum possible solar irradiance (1kW per m2), at the temperature of 25℃ or 77 ℉, and an air mass of 1.5 (related to the thickness of the atmosphere). But the actual outdoor conditions are various. The efficiency would be affected by shading, temperature, panel positioning, accessories loss, etc.
Solar Shading
Shading is one of the most important factors that reduce solar panel efficiency. It comes from lots of sources, such as trees and their leaves, buildings, other panels, clouds and more. And the effect of shading is highly variable.
Cells in a solar panel are usually connected in series to get a higher voltage and therefore an appropriate production of electricity. When one solar cell in a panel cell string is shaded, the current is no longer evenly distributed across all the cells. The hot spot effect occurs when the current cannot flow around weak cells. Eventually, the current will concentrate in a few cells, causing them to overheat and possibly melt.
The hot spot effect is one of the most common causes of solar panel failure or fire hazard. Therefore, the use of bypass diodes is critical to ensure that current can flow around weak cells while minimizing the shading effect under various shading conditions.
Temperature
There is a misconception that high temperatures increase the solar energy output. In contrast, solar cells are sensitive to temperature increases. Higher outdoor temperatures mean that the solar panel's semiconductor material heats up quickly and changes its properties slightly. It causes a slight increase in current but a bigger drop in voltage, which can damage or even degrade the performance of the system. Long-term exposure to high temperatures may also shorten the life of the material.
The maximum power of the solar cells was tested at a STC temperature of 25°C. The actual outdoor working temperature of solar panels is generally higher than 25°C, and the heat dissipation conditions are variable. According to some researches, the loss of temperature affecting solar panel efficiency is 0.5% per degree increase over 25°C. In summer, the temperature easily exceeds 45°C, which may reduce the power output of the solar panel by 10%.
On the other hand, you don't need to worry about cold temperatures, as long as the sun is shining and the solar panels receive unblocked sunlight during the day, they will produce at their estimated efficiency. The only common problem with solar production in winter is that there are far fewer sunny days than in summer, and the solar system produces less electricity per month.
Orientation & Angle Of Panel Installation
Your solar panel will have the best power output when the solar panel surface is perpendicular to sun light. However, as the sun moves across the sky, so do their angles.
If you want to improve the efficiency, you need to make solar tracking, adjusting the position and angle of the solar panels. In this way you can keep the solar panels always facing the maximum sunlight exposure at the best angle.
Sun Intensity
The intensity of sunlight variably changes the efficiency of a solar panel throughout the day. The solar panel can produce more energy output approximately in the afternoon when the sun exposure is at its peak.
Cloud Covers
Cloud cover reduces the amount of sunlight reaching the solar panel, which reduces the efficiency of the solar panel. But this is not something to worry about too much. Although cloud cover reduces the energy efficiency of solar cells, they can still produce energy. It doesn’t cause damage to panels, compared with the tree or building shading.
Solar Accessories Efficiency
Solar inverters, charge controllers, and installation wires all affect the performance of a solar system. You should choose quality accessories that are compatible with solar panels. Avoid damaging these accessories as this will reduce output.
You should also consider the cable size to avoid excessive resistance that reduces efficiency. For example, a 220V device will degrade the performance of a 48V solar panel system.
Maintenance Practice
New research from Duke University and the Indian Institute of Technology Gandhinagar shows that pollution can reduce the efficiency of solar panels by up to 25%.
Dust deposited on the surface of the solar panel will firstly reduce the light transmittance of the module surface, and secondly, it will change the incident angle of part of the sun light, resulting in uneven light propagation. So, cleaning solar panels regularly is important.
Also, you should be careful when you set up and store your portable solar panels. A lot of people store their portable solar panels under their beds in RVs. And probably they also put some other appliances on top of the solar panels. When taking the panels out, they do not remove these items first, but directly extract the panels with force. This action will cause the surfaces of the folded solar panels to rub against each other, causing a lot of scratches, affecting the power output. And it may even cause breaking the built-in wires of the solar panels, resulting in the inability to solar energy output.
Many people feedback that their solar panels did not work when they set up the panels after several days of storage. That may be the reason.
Read this article to get tips on how to protect your foldable monocrystalline solar panels.
Mismatch of Panels
Due to manufacturing differences, modules of the same type may have slightly different electrical characteristics. This mismatch between modules results in a performance penalty.
Some of these factors cannot be influenced by people, such as weather and temperature, and some of them can be changed, such as regular cleaning, the best installation angle and location. In order to obtain more power output, it’s important to learn more about the relevant knowledge and take proper action.
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