How to Calculate Solar Panel Efficiency? Follow an Ultimate Guide

The solar panel is a static electronic device used to generate electricity by converting renewable energy. That’s why efficiency comes into question. Efficiency is a crucial thing for any electrical and electronic device. There is a basic solar cell efficiency formula and this solar PV module efficiency calculation is considered a basic efficiency calculation formula. Electrical efficiency is defined as the output power of a circuit divided by the input power of a circuit. The solar panel is an electronic device that’s why the efficiency of solar panels can be defined this way. If we think about solar panels the efficiency of the solar panel depends on the sunlight and the radius of the solar panels. However, let’s see how to calculate solar panel efficiency whenever you buy solar panels. 

How to Drive Solar Panel Efficiency Formula?

If you would like to calculate solar panel maximum efficiency then you have to figure out the ratio of solar panels and the solar power by the panel area in square meters and multiply by percentage. However, let’s see the solar panel maximum efficiency formula. Efficiency = Panel Power in KW/Panel length * Panel Width.

To specify this formula, you can multiply with 100 (percentage). Suppose you have some PV panels each panel capacity is 200 watts (0.2KW) and length is 0.1.50m and the width is 0.90 and multiply by 100%. So, the solar panel efficiency formula derivation is efficiency = Panel Power / Panel length * Panel Width * 100%

                               0.2KW /1.50 *0.90 *100% = 14.9%

There are three main types of solar panels you can use this formula and remove your fear of how to calculate solar panel efficiency.

How to Calculate Solar Panel Efficiency?

How to calculate the efficiency of solar cells? There is an easy solar cell efficiency calculation process that we will let you know literally. Whenever you go to buy a solar panel you should understand how it is suitable for you and how much power you need. If you would like to buy a solar panel first of all you have to know your load demand, PV cell efficiency, and cost. However, let’s see how to calculate solar panel efficiency whenever you buy solar panels.

  • First of all, you have to decide the rated power of the solar panel (how much energy you need).
  • Find the length of the solar panel.
  • Find the width of the solar panel.
  • Figure out the area of the solar panel.
  • Figure out the output power of the panel.
  • You have to know the input power of the solar panel.

However, we are going to explain the solar panel efficiency equation or solar module efficiency calculation. Suppose you have a solar panel that has 350 watts, a length of 1.985, a width of 1.003, and an area of 1.991m2 and output power is 175.8 watts/m2 and the input power is constant at 1000 watts/m2. However, the exact or current solar panel efficiency formula is given below. The Efficiency = Panel Power in KW/Panel length * Panel Width

It is noted that this formula will lead you to find how is the solar panel efficiency or how to do solar panel efficiency calculation that you necessary to know before you buy solar panels, and before installing photovoltaic cells.


In this case, to find the area you have to multiply the length and width (1.985 * 1.003). After obtaining the area of the panel you have to divide it by the solar panel’s total watt and the area of the PV panel (350/1.991) then you will get solar panel output power.

It is noted that solar panel input power is 1000 watts/m2 it is a constant or world standard value that we get from sunlight. Now the formula for the efficiency of a solar cell is out power divided by input power (1.75.8/1000) = 17.57% the total efficiency of your decided solar panel is 17.57%. This is the solar PV efficiency calculation you can find the efficiency of any solar panel by using this method.

Monocrystalline Solar Panel Efficiency

The Monocrystalline solar panel is a solar panel that is made from silicon but to manufacture a Monocrystalline solar cell a seed crystal is submerged in a liquid silicon bath that’s why the Monocrystalline solar panel is considered a highly efficient solar panel in the world.

We have seen the Monocrystalline solar cell efficiency calculation and we got to prove that the Monocrystalline solar cell performance is higher than the Polycrystalline solar panels. It is noted that the Monocrystalline solar panel is the maximum efficiency of solar cells and the mono solar cell is the most efficient photovoltaic cell.

 The Monocrystalline solar panel efficiency is more than 28% and it is the more useful solar panel that can easily generate higher energy than Polycrystalline solar panels. However, it is noted that if you would like to find Monocrystalline solar cell efficiency then you should follow the above solar cell efficiency equation and it is the easiest process to find photovoltaic cell efficiency.

Polycrystalline Solar Panel Efficiency

The polycrystalline solar panel is a popular solar panel that has a large number of silicon crystals in one Photovoltaic cell. Silicon photovoltaic cells have an efficiency of 25% to single crystalline cells. Nowadays Polycrystalline solar panel efficiency is 23% but scientists are trying to improve it the conversion of a polycrystalline silicon solar cell efficiency is 13% to 16% but it is improving gradually.

Basically, the efficiency of solar cells depends on the panel construction. On the other hand, Polycrystalline solar panel prices are comparatively lower than Monocrystalline solar panels. For those who would like to use it for lower load, Polycrystalline is perfect there. So calculate solar panel efficiency whenever you buy solar panels but don’t buy low-efficient solar panels for your home, offices, and industries.

Thin Film Solar Cell Efficiency

The thin film solar cell is one of the second-generation solar cells that have been created with the help of more than one layer, or thin film of the photovoltaic material which involves glass, metal, and plastic. Thin Film solar cells are profitably used in many technologies including cadmium telluride (CdTe), amorphous thin-film silicon (a-Si, TF-Si), and copper indium gallium diselenide (CIGS).  

Since the late 1970s, the thin film cells have won the hearts of millions. The product has achieved a way more famous when the solar calculators are vitalized by the small strip of amorphous silicon which has been developed in the market. These items will be available in the vehicle charging systems and building integrated solar panel installations.

Even though, thin film technology was anticipated to bring better and more advanced one and transcend the crystalline silicon (c-Si) technology in the interminable, market share has been diminishing for several years now. Back in 2010, there was an efficiency of standard PV module, the thin film was considered 15% of the potential market which was reduced by 8% in 2014. This situation was expected to improve by 7% in 2015; along with amorphous silicon, it was anticipated to experience half of the market share by the end of the time.

Thin film solar cells are less expensive than Monocrystalline and Polycrystalline solar panels. Usually, they have low power capacity and are less efficient. The efficiency of the thin solar cell depends on the thin film photovoltaic cell. In 2015, the globe’s biggest copper indium selenium solar cell also known as Solar Frontier.

It receives a conversion efficiency of 22.3%. The conversion efficiency has risen by 0.6% but maximum thin film solar absorbs an efficiency rate of 6% to 18%. It is noted that you can choose one within three of them as your high-efficiency solar PV modules.

What Does 20% Efficiency On a Solar Panel Mean?

A solar panel’s efficiency rating is a measure of how much of the sunlight that hits the panel is converted into usable electricity. A 20% efficient solar panel means that 20% of the sunlight that hits the panel will be converted into electricity.

For example, if a 20% efficient solar panel is exposed to 1,000 watts of sunlight. It will generate 200 watts of electricity. The remaining 800 watts of sunlight will be reflected or absorbed by the panel and not converted into electricity.

Solar panel efficiency is measured under standard test conditions (STC), which are defined as

  • Airmass 1.5
  • The irradiance of 1,000 watts per square meter
  • Temperature of 25 degrees Celsius

Solar panel efficiency has been increasing over time, and panels with efficiencies of up to 22% are now available.

What Factors Can Affect Solar Panel Efficiency?

Some crucial factors can affect solar panel efficiency. Take a look few of them.

1. Panel Construction

The type of solar cells used in a panel, as well as the way the cells are arranged, can affect efficiency.

2. Angle of Sunlight

The angle of sunlight that hits a panel can affect how much sunlight is converted into electricity. Panels that are angled toward the sun will be more efficient than panels that are angled away from the sun.

3. Shading

Shading from trees, buildings, or other objects can reduce the amount of sunlight that hits a panel and therefore reduce its efficiency.

What is the Solar Panel Backup Time Calculation Process?

There is an easiest calculation to know about solar panel backup time. However, let’s see the solar panel backup time calculation process.

  1. Calculate your total power consumption. This includes the power consumption of all the appliances you want to run during a power outage. You can find this information on the appliance’s labels or in the owner’s manual.
  2. Choose a battery size. The battery size will determine how long your solar panels can power your appliances during a power outage. A larger battery will provide more backup time, but it will also be more expensive.
  3. Consider other factors. Other factors can affect the solar panel backup time, such as the amount of sunlight available and the efficiency of the battery. You should also consider the size of your solar panel array when calculating the backup time.
  4. Calculate the battery backup time. The battery backup time can be calculated using the following formula:

Battery backup time (hours) = Battery capacity (Ah) * Battery voltage (V) / Total power consumption (watts)

For example, if you have a 100 Ah battery capacity and voltage range of 12 V, and your total power consumption is 500 watts. So, battery backup time = 100 * 12/500 = 2.4 hours

So, your battery backup time will be 2.4 hours.  

Why Solar Panel Efficiency is Low?

Why solar panel efficiency is low? The answer is straightforward. It means PV panel efficiency depends on a few factors such as Photovoltaic length and width, solar energy materials and solar cells, or solar panel materials. Basically, solar panel efficiency depends on sunlight and solar panel size. However, efficiency is important and output power depends on efficiency. If efficiency becomes high then the output power or energy conversion will be high.

PV panel efficiency is not exactly low and this efficiency is higher than some other natural energy sources. The solar panel efficiency is 15% to 22% but the average efficiency is more than 20%. It is noted that panel efficiency depends on the size of the solar panel.

However, if we compare efficiency with some other commercial energy sources (coal, oil, and gas) then solar energy efficiency is high based on overall consideration. It is noted that solar panel efficiency becomes low during off-sun periods like rainy days and cloudy weather. However, let’s see a few reasons why solar panel efficiency is low.

1. The Bandgap of the Semiconductor Material

The bandgap is the energy difference between the valence band and the conduction band in a semiconductor material. Only photons with energy greater than the bandgap. It can create electron-hole pairs, which are the basic building blocks of electricity in a solar cell. So, if the bandgap is too high, then many of the photons hit the solar cell. However, it will not be able to create electron-hole pairs, and the efficiency will be low.

2. Recombination Losses

Recombination is the process by which electron-hole pairs recombine and release their energy as heat. It is a natural process that happens in all semiconductors. It can be a major source of efficiency losses in solar cells. Numerous factors can contribute to recombination losses, such as defects in the semiconductor material, impurities, high temperatures, etc.

3. Reflection Losses

Not all of the sunlight that hits a solar cell is absorbed. Some of it is reflected, which reduces the efficiency. The amount of reflection depends on the properties of the solar cell’s surface, such as its smoothness and the wavelength of the sunlight.

4. Temperature Effects

As the temperature of a solar cell increases, its efficiency decreases. This is because the bandgap of the semiconductor material increases with temperature. It makes it more difficult for photons to create electron-hole pairs.

Despite these challenges and effects, solar panel efficiency has been steadily improving over the years. In 2023, the average efficiency of commercially available solar panels was around 20%. This means that about 20% of the sunlight that hits a solar panel is converted into electricity.

Fill Factor and Efficiency of Solar Cell

The fill factor is a parameter that operates with Voc (open circuit voltage) and Isc (short circuit current) which controls the maximum power of the solar cell. The Fill Factor is the ratio of maximum power from a solar cell of the products f Voc and Isc. 

FF = Pmp / Voc * Isc

The open circuit voltage and short circuit current are the voltage and the current respectively of a solar cell. The fill factor (FF) estimates the squareness of a solar cell and the largest area of the rectangle which do fit the IV curve. The equation describes the importance of the Ideality Factor and it can also be recognized as the “n-factor” of a solar cell.

The ideality factor evaluates the quality of the junction and types of recombination of a solar cell and the value of the n is nevertheless, some of the mechanisms of recombination have inaugurated that the value of the recombination mechanisms is the FF always remains lower since there is a presence of parasitic resistive losses.

The FF is usually used for the measurement from the IV curve. Many successful businesses love spending on profit-oriented solar panels. Some solar panels don’t receive enough maintenance to produce better output to generate electricity. There are several ways through which the efficiency of profit-oriented solar panels can be improved.

1. Buy Better and More Efficient Models of Solar Panels

The efficiency of the panels is hitting the panels of photovoltaic solar cells which later transforms into electricity. Better solar panels will provide the best results.

2. Buy strong Photovoltaic (CPV) Cells

The best solar panels provide 22% of efficiency and on the other hand, cells of CPV panels can generate 46% of efficiency. 

3. Avoid Installing Solar Panels in Covered Areas.

If the one photovoltaic cells remain in shaded areas the energy can be generated by the neighbor cells. This situation happens when resistors are within their power. The buildings and tall trees are the two delinquents in terms of shading solar panels. A planning process needs to be taken to select a better site and confirm that the shade will not create any concerns.

4. Hire a Professional to Install the Solar Panels

To receive and generate better electricity it is necessary to install the solar panel correctly. The solar panels should be fixed within 18 to 36 degrees so that the efficiencies are not harmed by the temperature. A gap between the roof and solar panels permits the air to pass and saves the photovoltaic solar panels from being warmed. 

5. Clean the Solar Panels

The dust and dirt can create low efficiency and reduce the output by 5%. The areas which cannot receive an adequate amount of rainfall might reduce the output by 20%. 

6. Observe the Out of the Solar Panels with Energy Management Software

The energy management software will help the owner to remain protected from any unpredicted circumstances and the output. 

What is the Average Efficiency of Solar Panels?

The average efficiency of solar panels is 15 to 18% but we can manually improve PV cell efficiency whenever we install the solar panels. It is noted that we hope we will get more efficient PV cells in the future due to technological expansion. However, the better the photovoltaic solar panel the greater output can be achieved from the sunlight.

It hits the cells and requires less surface area to fulfill the requirements in a better way. Solar panels generate energy efficiency from 11% to 15%, this is the percentage of solar energy which are transformed into functional electricity. The developments and advancements have been made to fulfill the requirements to meet household and profit-oriented needs.

Researchers are working very hard to upgrade the efficiencies of Photovoltaic technology. They have managed to achieve 40% efficiency with the aid of multi-function cells which are later transformed to apprehend divergent frequencies of light within the spectrum of electromagnetic.

Although, the large area can create less efficient energy and less expensive panels may save the costs of installation. We have shown above the process efficiency calculation and you can find your answer on how to calculate solar panel efficiency.

 Why Do Many People Believe That Solar Panels Are Not Very Effective?

Solar panels are a very effective way to generate electricity. PV panels are becoming more efficient and affordable all the time. Solar panels are a great way to completely minimize your home-connected fuel-generated electricity cost. So, what you can do before choosing the best solar panel? You can get help from someone specialist to do your research and installation.

You may be surprised at how effective they can be. Different people may indeed have different opinions. Those who don’t have better knowledge about PV panels such person may have that comment. However, we have found a few reasons why some people believe that solar panels are not very effective.

  • They may be unfamiliar with solar panel technology. 
  •  People may have had a bad experience with a certain brand or installation.
  • They may have misconceptions about the efficiency or cost-effectiveness of solar panels.
  • They may be influenced by the fossil fuel industry.

Final Thought

The future of solar panel efficiency will greatly impact massive competition in the market of solar panels. The competition may lead to lessening the prices of solar panels and will effectively generate efficient storage solutions. The solar panel grants are motivating households to install renewable energy conversion panels to generate electricity to complete important tasks or electrical load demands.

The researchers have stated that enhancing the rate of photovoltaic conversion efficiency helps to provide better energy out of solar power. Many businesses are taking measures to maintain and achieve maximum solar efficiency which helps to maintain optimal performance levels and saves time and money. The future solar panel efficiency partially depends on updated technology and research. Best research and technology can give us highly efficient solar cells. However, we have given a simple calculation process to clarify how to calculate solar panel efficiency.

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