The History of the Radio.

Essay by @coHigh School, 10th grade September 2005

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Photovoltaic Cells

As our society expands, there become greater needs for energy. The rate that we are currently using non-renewable resources is dreadful and they will be depleted quite soon. And so we should begin focusing on other forms of energy that can be harnessed and converted to a useable form. One great source of renewable energy is the Solar Energy for our sun. This energy can be converted to a usable form in a variety of ways. I will explain how the Photovoltaic cell transfers the sun's rays into electrical energy. I will begin by describing the structure of a basic PV cell, then explain how the principles behind the structure, and finally I will show some of the PV cell variations.

The structure of a Photovoltaic cell is the key to how it functions and transfers energy. And so I will begin by explaining how a PV cell is put together.

There are multiple types of PV cells and there are more being designed as scientist experiment to make PV cells more efficient. But at the current moment, most PV cells are made from silicon. This silicon is in the crystalline form, meaning that each of the atoms is closely networked together. The silicon crystal is shaped into a thin, flat piece, called the PV cell.

This flat piece of silicon crystal is then doped, meaning impurities are added into its crystal form. The top layer of the cell is doped with phosphorous and becomes the n-type silicon. The top layer is called "n-type" because of the abundance of free electrons giving it a negative charge. The bottom layer is also doped, but this time with boron. This forms the p-type silicon, because of the lack of electrons and it's primarily positive charge.