 |
Photovoltaic
systems are solar systems that produce electricity directly
from sunlight.
These panels or cells can be used in a flexible way, not
just on the roofs of buildings, but in schools, gardens
and mobile living spaces.
Though still expensive compared to commercial power, solar
costs have fallen about 90 percent since the '70s.
History:
Solar power in almost all cultures has been worshiped
and praised, in 212 BC Archimedes allegedly used solar
energy to "reduce the Roman navy to ashes" by
having soldiers reflect sunlight off their shields toward
Roman sails.
In the modern world, Henri Becquerel discovered the photovoltaic
effect; that is, the production of electricity directly
from the sun.
Solar cells constructed from selenium were first manufactured
in the 1950's by the US corporation Bell.
In past decades photovoltaic technology has been steadily
developed, especially in the area of aerospace technology.
Key elements:
*Photovoltaic, translated simply means means "light
electricity".
*Silicon is the main material in 98% of solar PV cells
made today.
*All PV cells have at least two layers of such semiconductors:
one positively charged and one negatively charged.
When light shines on the semi-conductor, the electric
field across the junction between these two layers causes
electricity to flow.
*The lifetime of the PV module is estimated to be at least
20, maybe 30 years.
|
| |
|
 |
|
