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Photovoltaïc walkPhotovoltaic ( PV ) is the technology that generates direct current (DC) electrical power measured in watts (W) or kilowatts (KW) from semiconductors when they are illuminated by photons.  As long as light is Shining on the solar cell (the name for the individual PV element).

It’s able to generate electrical power when the there’s no sunlight or even during power outage. Solar cells never need recharging like batteries. As they are always  in a continuous outdoor operation on earth or in space for over 30 years.

How Does Photovoltaic (PV) Work ?
Solar cells are originally made of Semiconductor materials, which have weakly bonded electrons occupying a band of energy called the valence band.

So when energy exceeding a certain threshold, called the band-gap energy, is applied to a valence electron, the bonds are broken and the electron is Somewhat free o move around in a new energy band called he conduction band where it can conduct electricity through the material.

Thus, the free electrons in the conduction band are separated from the valence band by the band-gap (measured in units of electron volts ). This energy needed to free the electron can be supplied by photons, which are particles of the sunlight.

Advantages Of Photovoltaic
-Fuel Source is vast , widely accessible and essentially infinite.

-No emissions, combustion or radioactive waste ( doesn’t contribute perceptibly to global climate change or air/water pollution).

-Low operating costs (No Fuel).

-No moving parts (No Wear): theoretically everlasting.

-Ambient temperature operation (no high temperature corrosion or safety issues).

-High reliability of solar modules (manufacturers guarantees over 30 years).

-Rather predictable annual output.

-Modular (small or large increments).

-Can be installing into a new or existing building structures.

-Can be very rapidly installed at nearly any point-of-use.

Disadvantage of  Photovoltaic
-Fuel Source is diffuse (sunlight is relatively low density energy).

-High initial (Installed) costs.

-Unpredictable hourly or daily output.

-Lack of efficient energy storage.

Photovoltaic (PV) Technology
The human race is increasingly aware of the need for sustainable development. Solar energy is almost the only  and certainly the most developed way of producing energy for this sustainable development , This will be possible mainly through PV.

PV constitutes a new form of producing electric energy that is environmentally clean and very modular. It’s highly appreciated by the public. It’s unique for many applications of high social value such as providing electricity to people who lack it in remote areas.

In recent years PV has experienced an unprecedented burst of growth.Today PV is a big business of around 50 billion US$ and growing at 50% annually, As PV-powered homes, commercial buildings and power plants have been built around the world.

Photovoltaic (PV) Electricity Vs Nuclear Power
It has been recently shown in Spain that PV electricity can be installed five times faster than nuclear power plants and the a penetration of intermittent electricity of around 15% can be handled by the electric grids with positive environmental effects.

Future of  Photovoltaic (PV) Electricity
Common forecasts predict that PV electricity will contribute only a few percent by 2030. As a mater of fact there are easily enough lands,  raw materials,  safety protocols, capital,  technological , knowledge and Social support to allow PV to provide over 12% of our electrical needs by 2030.

And we have to be much more ambitious for the future because PV has to become the biggest supplier of electricity by the end of this century. this will require finding new ways of energy storage.

The present PV Development as been possible by he public support , driven by public opinion, which has led to governments spending Substantial money to subsidize PV. However , this has not been a waste . It has been an investment.Today PV electricity is very close to grid parity.

Political Support For Photovoltaic (PV) Technology
Thanks to this we predict that PV will continue o grow at a fast pace towards the 12% goal by 2030. Sill strong political Support will be necessary. And e promise of significant growth in employment – due to raw materials processing. module manufacturing, installation and non-PV system components – is becoming a major driving force behind that political Support.

PV possesses a panoply of novel technologies that ensure a continuous advance in the reduction of costs throughout the whole century. In this PV is unique compared with other energy technologies. Nations that want to lead this irrepressible will have to support it by investing in R&D , Industry and markets.


Handbook of Photovoltaic Science and Engineering (Hardcover)

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