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How do we measure Solar Panel Efficiency?
The efficiency of anything calculates how well the input is converted into output. In the case of solar panel efficiency, it is a measure of how well solar panels can convert the trapped sunlight into electricity. With technological advances, efficiency has improved with time; now, you can get more energy with fewer panels compared to the past.
Factors Affecting Solar Panel Efficiency
Your solar panel efficiency depends upon five factors:
Temperature:
The excitement level of electrons determines their energy levels. However, despite what many people think, solar panels function better in lower temperatures. This is because of the electrons present on the thin layer of silicon.
These electrons tend to be less excited and calmer. This only increases their ability to transport themselves in great numbers through transmission lines to produce more electricity. In hot conditions, electrons will be more excited and chaotically moving in random directions.
This makes it difficult for them to travel easily through transmission lines. Ultimately, this causes decreased solar energy generation on a hot day. Simply put, you’ll get improved solar generation efficiency and a higher voltage on a cold sunny day and lower efficiency on a hot sunny day.
Age:
Solar panels can last anywhere from 25-30 years. During this period, solar panel efficiency gradually drops but can drop drastically if sunlight is blocked by debris, dirt, or shade. Besides this, the slow but gradual decline in efficiency will reach a point where your solar panels won’t generate enough electricity to match your needs. When manufacturers design solar panels, they consider this degradation rate in the initial design, but it will still affect your solar panel efficiency.
Reflection:
The amount of light captured and reflected by a solar panel also impacts efficiency as more light reflection means low light capture hence low efficiency. Plus, not all the light collected is converted to electricity. Some is bound to be wasted as heat energy. Anti-reflection coatings and textured surfaces can help lower the reflection of light.
Wiring:
Different wiring configurations like parallel and series wiring can impact efficiency. The best way to go about this decision is through a solar panel company. They can help you find a design that is ideal for your home.
Inverters come in many types, like microinverter, string inverters, hybrid inverters, or power optimisers. Wiring also helps you in understanding which inverter will be the right choice for your solar arrays.
Different inverter types, their collection of energy from your panels, sending it to your home, and the type of battery storage all play an important role in deciding the efficiency of your solar panel system.
If you go deeper into the wires, you’ll find busbars. These metal components connect solar cells in a solar panel to capture sunlight and transfer energy. This has a huge impact on solar panel efficiency. With different configurations and improved technologies, it’s possible to increase efficiency.
Materials:
Solar panels can be made by using different kinds of materials:
- Multi-junction solar cells.
- Cadmium telluride.
- Monocrystalline silicon.
- Polycrystalline silicon.
Different materials have different efficiencies when they are used to make solar panels. Today, monocrystalline silicon solar cell technology is used for most solar panels due to its superior efficiency. Its efficiency comes from the manufacturing process, as it’s made from a single crystal of silicon. This makes it easier for electrons to flow through a cell.
Calculating Solar Panel Efficiency
You can calculate solar panel efficiency with this formula:
Efficiency (%) = (Pmax ÷ Area) ÷ (1000) x 100%
1000 = Standard Test Condition (STC) irradiance
Area = length x width of the solar panel (in m2)
Pmax = max solar panel power (in Watts)
Let’s simplify things.
STC:
Standard Test Condition (STC) is the ideal environment used by solar manufacturers when checking the average solar panel output. An air mass of 1.5 and a cell temperature of 25 °C are used in these conditions. The solar irradiance is set to 1000 W/m2. The efficiency equation makes use of the value of 1000 W/m2.
Area:
You can easily calculate the power unit area of your module by dividing its Pmax into its area.
Max Power Capacity:
The specifications sheet on your solar panels specifies your solar panels’ maximum power or “Pmax”.
Physical Dimensions:
You can find the length and width of your solar panels on the specifications sheet.
Solar Panel Efficiency:
A sample calculation will help you calculate your solar panel’s efficiency. For example, if your solar panels capture 1,100 W/m2 of sunlight, are 4m2 in area, and generate 500 watts of power, we can calculate their efficiency:
Efficiency (%) = (500 ÷ 4) ÷ (1100) x 100%
Efficiency = 11.36%
In 2022, the efficiency of a solar panel is between 15-20%. The highest efficiency seen in a solar panel is 22%. With advances in technology, these numbers will only rise.
Higher Efficiency Of Modern Solar Panels
The increased efficiency of modern solar panels can be attributed to two main reasons:
Improved Materials:
Silicon has a long lifespan, is cheap, and has high efficiency. For these reasons, it has been the preferred choice of semiconductor material for solar panels and has been used for decades by solar panel manufacturers. Researchers are constantly finding new ways to increase the efficiency of solar panels.
Some methods are using next-generation growth methods, creating ultra-thin crystalline layers and developing production processes that remove silicone dust from solar cells. A promising material named perovskite has also shown potential for being a high-efficiency component in future solar panels.
Solar Power Research:
Scientists are constantly developing new methods to achieve higher efficiency in solar panels. There have been countless breakthroughs in the past decades that have only improved solar energy systems worldwide. This desire to increase efficiency pushes forward the research in solar research centers around the globe.
Some prominent names in research are The Swiss Center for Electronics and Microtechnology and the National Renewable Energy Laboratory. They have dedicated their expertise, resources, and technologies to experimental studies that will help develop high-output solar panels.
Improving Efficiency
Manufacturers design solar panels so that they require little maintenance or checking in by the homeowner. But if you want to improve solar panel efficiency and ensure that it stays that way, then you can clean your panels daily and prevent the shade from falling on your panels. Also, your panels might have issues that can lower electricity generation. If such a thing happens, you should contact your solar company.
What The Future Holds
The future for solar panels is bright as several research centers have collaborated to increase solar panel efficiency through experimentation with new materials. These include:
- Quantum dots.
- Organic photovoltaics.
- Concentration photovoltaics.
- Solar fabric.
- Solar skins.
- Floating solar farms (“floatovoltaics”).
- Perovskite solar cells.
- Building-integrated PV panels.
Floating solar farms have been shown to generate more electricity than rooftop or ground-mounted installations. This is due to the cooling effects of the water, which improves efficiency. This is why these solar farms are being deployed worldwide. Solar skins and building-integrated PV have been used in many applications too. The new solar technology shows promise and a bright future for increased efficiency.
