Solar Energy Efficiency

Wondering about solar energy efficiency?

It is well-known that solar energy (or light and heat energy from the sun) is renewable, and in fact in constant supply so long as the sun continues to shine. Solar energy is also cleaner.

Before we look at the efficiency of solar energy, we need to have some understanding of how solar energy is captured.

Solar energy is captured by solar cells on the solar panels, which converts the solar energy from sunlight directly into usable forms of electricity via the photovoltaic effect – photons in sunlight are absorbed by the semiconducting materials (eg. Silicon) on the solar panels, causing electrons to be dislodged from their atoms and creating a Direct Current (DC) electric flow. Read more facts about solar energy and solar panels.


Determining the efficiency of solar energy

In turn, the efficiency of solar energy is determined by the efficiency of these panels.

The efficiency of solar energy can be affected by the absorption of the solar panels. Where solar panels are designed to absorb sunlight only from a single angle, the efficiency of a panel changes over time (as the Sun moves across the sky), and is in fact low relative to the cost of the panels. To overcome this obstacle to efficiency, ways must be found for the panels to always point at the sun.

Another factor for solar efficiency is the amount of captured solar energy that can be converted into usable electricity. Whether all the photons from the sun that reach the solar panels can be absorbed by these panels depends on the energy level of the incoming photons relative to the band gap of the absorbing material on the panel. Where the band gap of the absorbing material is lower or higher than the energy level of the incoming photons, a fraction of the energy from the sun is not converted to useful output and is wasted. The use of solar cells with multiple band gap absorber materials hence helps increase the efficiency of conversion of the solar spectrum to electricity.

Most solar panels convert about 10% to 15% of the energy from the sun into usable and storable energy. Even the most advanced and efficient solar panels might only have a solar energy efficiency rate of 40%. This means that of all of the light and heat energy that hit the panels, only about 40% of it is actually trapped and converted to usable energy. That said, these panels are currently very expensive and highly complicated.

The efficiency of solar energy that we now know of may soon be challenged by the newer and potentially more efficient panels currently being developed by the Idaho National Laboratories. According to Steven Novack of Idaho National Laboratories, the new panels being developed have a solar energy efficiency of about 80%, twice as high as the most advanced panels currently on the market. These new panels are foldable and lightweight and use the infrared radiation emitted by the sun. As such, the panels will continue to be operational even at night.

Scientists are constantly looking for new ways to increase the efficiency of solar energy. In the midst of this search process, making sure that the materials used and the new technologies involved are affordable is high crucial. For if solar energy remains expensive and exclusive, even if solar energy efficiency can be raised to its peak, solar energy would remain a white elephant. Read about the advantages and disadvantages of solar energy.

Read articles related to solar energy.

Return to page on Alternative Forms Of Energy from this page on Solar Energy Efficiency

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