Solar+cells+-+Yong+Chen

=__**Photovoltaic**__=
 * __What is Photovoltaic?__**
 * Photovoltaic** is the direct conversion of light **(light energy)** into electricity **(electrical energy)** at the atomic level. Some of the material in everyday life shows signs of photoelectric effect that causes them to absorb photons of light and release electrons. When these free electrons are captured, an electric current results that can be used as electricity. Photovoltaic is a **renewable energy source**, it gets more of its energy from the Sun and is now expanding rapidly over the past few years. Photovoltaic **does not** do any impact to the environment unlike coal energy plants but the production of the panels can cause some pollution. Photovoltaic does not cause any effects to global warming, they make no noise and pollution in operation. It is clean, silent and freely available.


 * Photon** - a particle representing a quantum of light or other electromagnetic radiation. A photon carries energy proportional to the radiation frequency but has zero rest mass.

__**Positive things about photovoltaics**__ - They are a renewable energy source - They do not cause any harm to the environment - They can be install on buildings
 * Quantum** - a discrete quantity of energy proportional in magnitude to the frequency of the radiation it represents

- They depend on the Sun (not 24 hours base) - They take up a lot of space on earth - They are expensive to set up
 * __Negative things about photovoltaics__**
 * __How Does it Work?__**

The diagram shows the operation of a basic photovoltaic cell that is also known as a solar cell. Solar cells are made of semiconductor materials such as silicon. When the light energy strikes the solar cell **(light energy)**, electrons are knocked loose from the atoms in the semiconductor material; the electrons are then captured in the form of electricity **(electrical energy)**. These solar cells can be connected together to form modules, these modules can then be connected to form PV arrays of different sizes and power output.

Waldpolenz Solar Park is one of the world’s largest photovoltaic power plants, it cost 130 million euro to build. The power plant is located in Germany build in 2008, the power plant is about 2 square kilometers located at a former military base. The power plant is designed to produce 40 mega watts of energy, which is enough electricity for 40,000 German homes; the fee is about 3250 euro per kilowatt.
 * __Waldpolenz Solar Park__**