​How Efficient Are Solar Panels [2024 Guide]

Solar panel efficiency measures a solar panel's ability to convert sunlight into electricity. Under the same conditions and timeframe, higher efficiency panels generate more electricity. This article will help you understand solar panels efficiency, the factors that affect it, and why it is so important.

What is Solar Panels Efficiency

A solar panel is the most important component of a  photovoltaic system and is responsible for absorbing sunlight and converting it into DC currents. The efficiency of a solar panel represents its ability to convert sunlight into usable electricity. How efficient are solar panels? Actually, Solar energy efficiency varies across different applications and types of solar panels in 2024.

What Types of Solar Panels Are the Most Efficient

Due to differences in scale, the solar efficiency of traditional residential panels and commercial panels varies. For traditional residential use, monocrystalline solar panels have an efficiency range of 18%-22%, polycrystalline panels range from 15%-18%, and thin-film panels have the lowest efficiency at 10%-12%.

Commercial solar panels, typically installed on large rooftops or open spaces with no shading, generally have higher efficiency. Monocrystalline panels range from 19%-24%, while polycrystalline panels range from 16%-20%.

Why Is Solar Panel Efficiency Important?

For some areas with limited roof space or high electricity demand, choosing high-efficient solar panels can meet your requests. Here are some of the pros of high-efficiency solar panels.

Generate More Solar Power

High-efficiency solar panels produce more electricity from the same amount of sunlight compared to standard panels which can save electricity bills in the long term.

Save Space

Same space condition, installing high-efficiency solar panels can generate more electricity which can meet the needs of households with small roof space and high electricity consumption.

Better Performance in Lacking-of-sunlight Condition

High-efficiency solar panels often perform better in low-light conditions such as cloudy or shaded environments. Because they use advanced technologies like high-quality silicon and anti-reflective coatings allowing them to maximize sunlight capture and enhance energy absorption and conversion.

Qualify for Higher Solar Incentives

Many governments and utilities offer incentives and rebates for installing high-efficiency solar panels. These financial incentives can help offset the initial cost and make the investment more affordable.

7 Key Factors Affect Solar Cells Efficiency

Temperature: high temperatures reduce the efficiency of solar panels because the voltage and power of the panels will decrease when they are overheated.

Shading: in the shade, the efficiency of solar panels will decrease because there is less area to absorb sunlight. Therefore, when installing solar panels, you should choose an open area without trees or other buildings blocking the view.

Angle and Orientation: the angle and direction in which solar panels are installed affect their exposure to sunlight. Optimizing the tilt and orientation can maximize sunlight capture and increase efficiency.

Dirt and Debris: solar panels should be kept clean regularly to reduce the impact of surface dirt, dust and debris on solar performance and improve solar panel efficiency.

Inverter Efficiency: the efficiency of the inverter, which converts the DC electricity generated by the solar panels into AC electricity for use in homes, plays a crucial role. High-quality inverters minimize energy loss during this conversion process.

Wiring and Connections: loose or poor wiring inside the solar system will cause energy loss and reduce the efficiency of converting sunlight into electricity.

Reflective Coatings: some solar panels are coated with anti-reflective coatings on the surface to reduce the reflection of sunlight so that they can better absorb sunlight, especially in low light conditions.

How Solar Panel Efficiency is Calculated

You may be wondering how efficiency is calculated and how solar companies use them as a selling point. Below is a step-by-step demonstration of how to calculate the efficiency of a solar panel.

Calculating efficiency ratings is easy. You can do it with a simple math equation. It’s really just the ratio of a panel’s power output to the solar energy absorbed on the surface of a panel under standard testing conditions. The equation below shows just how easy it can be.

Module efficiency VS. Cell efficiency

To understand solar panel efficiency, first we need to understand solar cell efficiency. We know module efficiency is the ratio of the power a module can produce to the solar energy hitting the surface of a panel under standard testing conditions. But for solar cells, efficiency is calculated using the same ratio but there’s a gap between these two efficiency ratings. There’s a gap because the cell efficiency is calculated with the area of a single cell. In contrast, the module efficiency includes other aspects of a panel’s construction. This includes shading that may come from other components in the panel such as busbars, or space between cells that may lead to energy loss.

At Renogy, we refer to cell efficiency when talking about solar panel efficiency since cells are the fundamental components of a module. You can also find cell efficiency ratings in the specification section of a module.

Breakdown of calculation

Let’s use what we’ve learned to calculate efficiency with our popular 100W Monocrystalline Solar Panel (Compact Design)

Step 1: Determine the module’s maximum power output under optimal conditions

To get the maximum power output of a solar panel (Pmax), we use the maximum power output of a module before the encasing process. After encasing solar cells in glass, the extra layer reduces sunlight absorption, leading to a lower efficiency rating. This figure should be in Watts (W). In the case of our 100W monocrystalline solar panel (compact design), the maximum power output of the module before encasing is 108W after testing in the lab.

To get the maximum power output of a solar cell, divide maximum power output by the number of the solar cells in the module. In this case, the maximum power output a solar cell can deliver is:

108W/36 (pcs)=3W/cell

Step 2: Find the dimensions of the solar cell

You can find the dimensions of a module in its the specifications. The size information is either in millimeters (mm) or inches (in). You’ll need to convert these figures into meters (m) for other calculations.

The dimensions of this 100W solar panel are: 41.8 x 20.9 x 1.4 in / 1.06 x 0.53 x 0.035 m

The dimensions of its solar cells are: 6.5 x 3.3 in / 0.1651 x 0.08382 m

Step 3: Determine the module’s maximum absorbed power at standard testing conditions (STC)

First let’s look at the definition of standard testing conditions for the factors considered in panel efficiency.

• Irradiance 1000W/m2: This means 1000W of solar energy is absorbed by a square meter on a module at a given time.
• Temperature 25°C: Solar cells are tested at 25°C. Note that this does not refer to the ambient temperature.
• Air Mass 1.5: This metric is related to the angle the sunlight hits a given spot on the earth. The smaller the number, the smaller the distance sunlight needs to travel to reach the earth’s surface.

To get the maximum absorbed power at standard testing conditions, multiply the irradiance 1000W/m2 and the solar panel/solar cell area. In this case, the calculation is:

1000W/m2 x (1.06 x 0.53 m)=561.8W

1000W/m2 x (0.1651 x 0.08382 m)=13.8W

Step 4: Calculate cell efficiency

The final step is to divide the total power output by the absorbed energy of the panel/solar cell.

The module efficiency of this 100W solar panel:

100W/1000W/m2 x (1.06 x 0.53 m) ≈ 18%

The solar cell efficiency of this 100W solar panel:

3W/1000W/m2 x (0.1651 x 0.08382 m) ≈ 22%

The Efficiency of Solar Panels Under Extreme Weather

High temperature & low temperature

High temperature will increase the resistance in the panel circuit, and the efficiency of the solar panel will decrease. In a low temperature environment, thick snow is easy to accumulate on the solar panel. When the thickness of the snow on the solar panel exceeds 5cm, the solar cell will stop working. So the solar panel needs to be maintained regularly on snowy days to ensure that it works at normal efficiency.

Hail

Although solar panels are strong and durable, severe hail may still damage the solar panel, reduce its efficiency or even make it unusable.

Strong wind

Solar panels are easily affected by strong winds. As the wind speed increases, the efficiency of solar panels will decrease.

Ice

The surface of solar panels without silicon coating is prone to ice. The ice surface will reflect sunlight, and the efficiency of solar panels absorbing sunlight will be greatly reduced.

What Are the Most Efficient Solar Panels in 2024

Although not everyone needs to buy high-efficiency solar panels for their roofs, for financial reasons. But a solar panel that is efficient but not expensive is likely to be what everyone needs. Renogy provides  most efficient solar panels, including monocrystalline solar panels and bifacial solar panels of various wattages. The solar power efficiency can be up to 30%, and buying Renogy solar panels can also obtain a 30% residential clean energy credit.

The Future of Solar Panel Efficiency

The first selenium solar cell developed in 1883 by American inventor Charles Fritts, had an efficiency of just 1 percent. Today you can find a wide variety of solar panels with efficiencies ranging between 15 and 22 percent. The efficiency of current solar panels has increased significantly in recent years with advances in materials and technology, and the efficiency percentage of the most efficient solar panels can achieve about 22.8 percent. how efficient will solar power be in the future? we have no exact number but one thing is sure: plenty of solar technology advancements are coming soon.

FAQ

Can solar panels be 100% efficient?

No, There is no solar panels reach 100% solar efficiecy far from now. The National Renewable Energy Laboratory tracks the highest efficiencies achieved in standardized lab conditions in 2022. The highest-ever solar cell efficiency was 47.6%.

Is solar panel efficiency important?

Yes. The efficiency of solar panels is important. Under the same conditions, choosing high-efficiency solar panels can reduce energy loss, generate more electricity in the same time, and improve your economic benefits. But if you are short of money or your house has a large roof area, the efficiency of solar panels is not your priority.

Are more efficient solar panels more expensive?

In general, yes. higher-performance panels are typically more expensive.