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Photovoltaic cells look similar to solar panels but
they work in a different way. Solar panels are use to produce hot water
or even steam. Photovoltaic panels convert the sunlight directly into
electricity. A typical example of a device powered by photovoltaic cells
is a solar powered calculator. This type of device only needs a small
amount of electrical power to work and can even be used in a room with
artificial light (bulbs / fluorescent light).
Although we see photovoltaic cells powering small devices such as
calculators they have a more practical application especially in the
third world. Photovoltaic cells have been developed that will provide
electrical power to pump drinking water from wells in remote villages.
British Telecom have developed a system that can be used to power a
radio telephone system. During the day the cells power the phone and
also charge batteries. The batteries power the phone during the night.
Often photovoltaic cells are used as a backup to conventional energy. If
conventional fails the cells are used to produce electricity.
A TYPICAL PHOTOVOLTAIC CELL
Silicon is a material known as a ‘semiconductor’ as
it conducts electricity and it is the main material for photovoltaic
cells. Impurities such as boron or phosphorus are added to this base
material. These impurities create the environment for electrons to be
freed when sunlight hits the photovoltaic panel. The freeing of
electrons leads to the production of electricity.
The diagram above shows a basic photovoltaic cell.
The blue represents the main material, silicon. The black round and
irregular shapes represent the impurities of boron or phosphorous. As
the sun/light strikes the cell the impurities free up electrons which
‘bounce’ around at incredible speeds. This creates an electrical charge.
AN ARRANGEMENT OF PHOTOVOLTAIC PANELS - ARIZONA