Solar Power

How solar energy works

There are several different systems which use power generated from the sun:

• Photovoltaic modules convert solar radiation directly into electricity. Such modules are often used as roof tiles.
  
  
• A relatively simple method is to use solar energy to heat water pipes. Solar thermal collectors use the solar radiation falling on them to heat tap water (and, to a lesser extent, to heat water for space heating).
  
  
• Solar thermal power plants use solar heat by concentrating solar radiation (for instance using mirrors focussed upon a "solar power tower", or by means of parabolic troughs) to heat up water (or another medium), and conveying the steam to a turbine or a Stirling engine. 
  

Immense potential

Theoretically, the entire present energy consumption of the world could be met by an area of 700 km by 700 km covered in photovoltaic cells.

Today, direct solar energy use only makes a small contribution to overall electricity and heat requirements. Despite strong growth in recent years, the worldwide contribution is still well below 0.01%. The sector is forecast to continue to grow dynamically in the future, but is not expected to contribute 1% to total power production before the year 2020.

But in the medium term, both photovoltaics and solar thermal energy hold out a great utilizable potential. These are definitely technologies for the future, whose development and cost-reduction potential should be systematically tapped.

Investment

Many companies are now lining up to take advantage of this potential. One example is Nanosolar Inc., a Californian company which received start-up funding from 2 co-founders of Google. The company is building what is, to date, the world’s largest factory to produce solar cells. The annual output planned will deliver a capacity of 430 MW, equivalent to 1 coal power station. 

Off-grid

Photovoltaics have the additional advantage that they can supply power in sparsely populated off-grid areas, thereby improving quality of life and promoting sustainable development, particularly in rural areas of developing countries. Solar heat holds out promises for cities, where air pollution can be a big problem. Solar thermal power plants also open up the possibility of future power transfers from warm developing countries to cold developed countries.