Aug 2, 2011

Solar Cell Inefficiencies – Why are Efficiency Levels Low?

There has been plenty of talk about high efficiency solar cells but the figure only lingers around 15-20% and when breakthroughs are mentioned, the solar module efficiency rates only go up to 50%.

Sure, these numbers get higher each year, but it will take years before they get close to 100%. There are two reasons for the poor efficiency levels of solar cells.

Firstly, Sunlight (which bumps into electrons and makes them loose to complete a circuit) is not fully absorbed by photovoltaic solar cells: 
    Explanation: light is made of energies with different wavelengths (remember the 7 colors of the rainbow?) and photovoltaic material, the most common of which is silicon, can only absorb a certain range of wavelengths. As a result, the other light rays simply pass through the solar cell, and lead to losses in current production.
    The problem may be fixed if a photovoltaic material with a higher absorption band is used, but this compromises the current’s strength.
    Secondly, solar cells are made of semi-conductors that offer resistance to electrons:
      Explanation: since silicon is a semi-conductor, it isn’t a very good means of transporting current from the circuit to the appliance. Electrons loose some of their energy as they travel across the silicon solar modules to the metallic plates placed above and below the cell to collect the current.