Solar Panels for Electricity Generation

When certain solids came into contact with light, it frees negative and positive charges in the solids and creates electrical activity i.e. electricity in them. The famous scientist, Albert Einstein received the Nobel prize in physics for analyzing this phenomena which came to be known as 'the Photoelectric Effect'. The following section explains in brief, how this phenomena is implemented in solar panels for electricity generation. It is estimated that 30% of energy is used to heat water, which can be generated using solar panels. Solar panels for electricity generation can last upto 25 years and there is almost no expenditure in maintaining them.

A typical solar panel for generation of electricity contains 36 solar cells of different size, depending on the watt or amperage of the panel. A strong aluminum panel serves as a back for the solar panel, and is mounted in a tough frame. Monocrystalline or polycrystalline solar cells are used make rigid solar panels. Monocrystalline solar cells are made of thin wafers of silicon, which are 1 millimeter thick, that has been grown from a single silicon crystal. The yield of electricity from a solar panel made using these efficient solar cells, is more than polycrystalline solar cells.

Thin wafers of multifaceted silicon crystals are used to make polycrystalline cells. These are less efficient than monocrystalline solar celled solar panels. However, polycrystalline solar cells used in rigid solar panels are cheaper than monocrystalline solar cells.
In the northern hemisphere, the solar panels used for the generation of electricity must face the south and those in the southern hemisphere, must face the north to take the maximum advantage of the sunlight or the solar power available. The solar panel electricity production is measured in the units of kilowatts, wherein one kilowatt is equal to 1,000 watts. The solar energy emitted by the sun, on a clear day, on 1 square meter of the earth's surface, has the potential of producing 1,000 watts of electricity. The efficiency of solar panels range from 5-18 percent and mainly, depend on the type of solar cells used in it. Under laboratory conditions, multi-junction solar cells have achieved 40% efficiency. The sunlight, clouds, rain and snow are also major factors, that can affect the solar panel's electricity production. The scientists have solved the question, "How does a solar panel make electricity?".

How Does a Solar Panel Make Electricity

Solar cells make use of the photoelectric effect for the production of electricity. Pure crystalline silicon is a not a good conductor of electricity. Its electrons are not free to move about and carry an electrical charge. So atoms of other elements are added to 99.999 % pure silicon. Atoms of elements such as boron, added to silicon, results in a p-type silicon, which readily accepts electrons. Atoms of phosphorus added to silicon creates n-type silicon, which readily supplies electrons.

Solar cells, which are also known as photovoltaic cells, are made using a p-type silicon layer, n-type silicon layer and a transparent electrically conductive layer. It also has metal contact layer and a p-n junction. When sunlight falls on both the silicon layers of the solar cell, electrons and positive charges (protons) get excited and start moving within the layers. This flow of electrons is known as electrical current. These moving charges are then channelized through the electrical contacts laid on the solar cells to the junction box and emerge as direct current (DC) which can be used to charge batteries. The DC current is fed to an inverter an which converts it to alternating current and can be used power house hold electrical equipment.

Solar panels for electricity generation are also made by laying a layer of silicon on ether side of thin transparent sheets of various materials. The sheet is layered with solar cells such that, a p-type silicon layers of the solar cells is on one side of the sheet and the corresponding n-type silicon layers on the other side, opposite to the p-type layer. When sunlight falls on the these solar cells, it passes through the n-type silicon layer, transparent sheet and then it reaches the p-type silicon layer. This excites electrons and generates electrical activity which creates an electrical field around the middle sheet. Electrical current starts flowing through the sheet which is electrically conductive. The solar panels made using these solar cells are light and easy to handle. The method used to make these solar cells is inexpensive and does not waste precious silicon while making solar cells. Amorphous silicon is used to manufacture these solar cells.

Scientists at New Jersey Institute of Technology (NJIT) have developed a technology to make solar cells made of carbon nano-tubes which can be painted or printed on flexible plastic sheets. Scientists believe that the walls or roofs of houses painted with inexpensive nano-tube solar cells can be used as solar panels for electricity generation which can then be stored in generators for one's personal use.

Once solar energy was a hi-tech field. The space vehicle Vanguard-1, launched on March 17, 1958, was the first on to utilize solar panels. Now, scientists are trying to invent energy saving consumer vehicles by converting vehicle roofs into solar panels, by painting them with solar cells such as, nano-tube solar cells. Germany is the leader in using solar panels for the production of electricity. An installation, using solar panels for electricity production which is to the tune of 10 megawatt is located in Pocking, Germany. A solar farm in the Nevada desert in the United States, is expected to generate 15 megawatt by using solar panels for electricity production. There is a huge demand for solar panels in the Asian countries due the abundance of sunlight. Governments are offering to buy the excess electricity produced using the solar panels. The German government is paying as high as 4 times the normal rates to buy this type of electricity. An ambitious project to generate 300 megawatt of electricity is being planned in New Mexico. The whole world is gearing to convert as much of safe and free solar energy in electricity as possible.