Efficiency may be a valuable statistic to consider if you are searching for the finest solar panels.

The more efficient your solar cells are, the more power your system generates. In certain instances, you may install higher-efficiency panels and still satisfy your energy requirements.

What does the Efficiency of Solar Panels mean?

The efficiency of the solar panel is the proportion of solar energy that is transformed into electricity by the panel.

Let’s assume, for example, that the sun shines on your solar panel equal to 1 kilowatt (kW) or 1,000 W. Your solar panel transforms this energy into 200 watts of electricity for your house or company. This panel will have a 20% efficiency.

Today, most solar panels are between 17% and 19% efficient. The least efficient panels will be about 15% efficient, with an efficiency of just 23%.

What factors cause changes in the efficiency of the panel?

On the manufacturer’s website, the solar panel efficiency rates or the spec sheet of the solar panel is not necessarily the actual efficiency level of your panels once installed.

The figure announced by the manufacturer represents the efficiency of the panel under conventional test circumstances. These are laboratory-controlled settings that remain consistent throughout the business to take into consideration any potential variations. 

Measurements made under normal test settings make it simple to compare goods, but these circumstances are not always reproduced in the actual world.

Here are several reasons that may cause your solar cells to generate less energy than the spec sheet predicts.


Irradiance is the amount of energy that a region gets from the sun. The more energy your solar panels generate, the higher this value. Due to the tilt of the panels, seasonal changes in the sun’s position in the sky, or weather patterns, irradiance fluctuations to your solar system may occur.

The optimal tilt varies according to where you are. 

If you build a system at more latitude, the installation of your solar system will be better to a higher degree. If you are closer to the equator, the flatter it is, you will have a more efficient system. The degree tilt of your solar panel should match your latitude as a basic thumb rule.

As the season’s change, the sun’s rays touch the Earth differently. Due to the Earth’s tilt on its axis, the northern hemisphere receives the most significant direct sunlight in summer and the least during winter. Your solar system produces the more direct the sun, the more energy. During the summer season, when the sun is lower in the sky or the days are shorter, your production will be greater than during winter.

The weather may also affect irradiation. Whether they are white, fluffy or black and stormy, Clouds may prevent the sun from penetrating your solar panels. This will affect the energy generated by your solar panels.


You may believe that summer is the most efficient season of the year for solar panels. However, your solar system generates higher voltage and more energy when it’s colder out. When the temperature increases, solar panels produce less voltage and are less efficient.

Dust, pollution and shadow

Anything that hinders sunlight can impede the output of your solar panels. A heavy increase of dust and dirt may create enough obstruction to adversely affect the output of your solar system, mainly when you reside in a dusty region prone to drought. You can clean up your panels better, depending on how thick this coating of grime is and how frequently your area receives rain showers.

Besides dust and grime, a shadow from surrounding trees, houses, ventilation systems, or even rocks or hills may further decrease the output of your solar system by preventing sunlight penetration to your panels.

Why are solar panels not 100% efficient?

The highest efficient solar panel is 22.8%. This may feel overwhelming. But the sun provides so much energy that even a portion of it can power many houses, enterprises and farms.

A solar panel’s efficiency is restricted by the kind of energy produced by the sun. This energy covers a wide range. Just as a tiny percentage of this energy is visible to people, modern technology can only turn part of it into electricity using solar panels. 

Solar panel manufacturers’ research & development teams are constantly working on a more significant share of the energy in this spectrum and thus improve the efficiency of their panels.

Whether the efficiency of solar panels continues, you may question if you would better wait till technology develops a little further. But most people are not going to be better off since the tiny additional improvements in Panel efficiency will not compensate for months or years of free energy.