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ABOUT Solar Photovoltaics
HOW DOES IT WORK?
In simple terms…
Electricity is produced from sunlight through a
process called solar photovoltaics. Photovoltaic cells are made of
semi-conducting materials, so when the sunlight strikes, it is converted
into electricity.
The technical part...
The solar cells are made of several thin layers of
silicon. When sunlight strikes, the electrons within the cell are knocked
loose. By the absorption of a photon (light particle), the negative electron
gets shunted away from the silicon atom, and a positive 'hole' remains. The
freed electron and the positive hole together are neutral. Therefore, to be
able to generate electricity, the electron and the hole need to be separated
from each other. This is done by giving layers within the cell opposite
charges, so that the freed electrons cannot return to the positively charged
holes. When the electrical contacts on the front and rear are connected
through an external circuit, the freed electrons can only return to the
positively charged holes by flowing through this circuit, thus causing
electricity to flow. This means that the greater the intensity of light
(larger number of photons), the greater the flow of electricity.
...and what happens if the sun isn't out?
Even if the sky is overcast, PV still produces
electricity. This is because PV cells not only use direct sunlight, but also
diffuse solar radiation, which is light that has been scattered by dust and
water particles in the atmosphere. Obviously the amount of useful
electricity generated is proportional to the intensity of light energy which
falls into the conversion area. However, you can still have an electricity
supply even without the sun!
To determine the PV electricity generation potential for a particular site,
it is important to assess the average total solar energy received over the
year.
What about at night?
Despite its advanced technical capabilities, a PV
system will not generate electricity at night, but the system is able to
store collected energy in a battery for use during non-daylight hours.
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THE BENEFITS OF SOLAR POWER
Environmentally friendly
The PV modules are made out of silicon which is
entirely benign, and available in abundance. No noise pollution or harmful
gases are emitted during the operation.
Immediately available
PV utilizes the most abundant energy source on the
planet - the sun.
No barriers to installation
PV is not affected by 'Nimbyism' or affected by
planning delays.
Minimal maintenance
PV has no moving components and is virtually
maintenance free.
Flexible
PV systems can be incorporated into all types of
building, and retrofitted on existing roofs, or as part of the building
envelope at construction stage. It can be curved and shaped to the building
design.
Cost effective
In grid locations where grid connection is too
expensive.
Reduces energy bills
Having a solar roof provides you with a power source
that can be used to augment your grid connected electricity supply
subsequently reducing your electricity bills. In addition, having PV as an
energy resource increases your awareness of electricity use and encourages
more efficient energy behavior. This in turn leads to lower energy bills.
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