SOLAR CELL ENERGY

Solar cells are used to generate energy using the sun, which is a renewable source of energy, in place of using non-eco friendly methods like burning fuel. The increasing use of Solar cell technology to produce energy gives a clear indication of the increasing awareness about the declining level of fossil fuels and their impact on the environment. Today, the electricity produced through solar technology is being used to power homes, cars and appliances. This has made solar technology to be one of the most important advances in technology in recent times

The development of the solar cell stems from the work of the French physicist Antoine-César Becquerel in 1839. Becquerel discovered the photovoltaic effect while experimenting with a solid electrode in an electrolyte solution; he observed that voltage developed when light fell upon the electrode. About 50 years later, Charles Fritts constructed the first true solar cells using junctions formed by coating the semiconductor selenium with an ultrathin, nearly transparent layer of gold. Fritts's devices were very inefficient, transforming less than 1 percent of the absorbed light into electrical energy.
By 1927 another metalÐsemiconductor-junction solar cell, in this case made of copper and the semiconductor copper oxide, had been demonstrated. By the 1930s both the selenium cell and the copper oxide cell were being employed in light-sensitive devices, such as photometers, for use in photography. These early solar cells, however, still had energy-conversion efficiencies of less than 1 percent. This impasse was finally overcome with the development of the silicon solar cell by Russell Ohl in 1941. In 1954, three other American researchers, G.L. Pearson, Daryl Chapin, and Calvin Fuller, demonstrated a silicon solar cell capable of a 6-percent energy-conversion efficiency when used in direct sunlight. By the late 1980s silicon cells, as well as those made of gallium arsenide, with efficiencies of more than 20 percent had been fabricated. In 1989 a concentrator solar cell, a type of device in which sunlight is concentrated onto the cell surface by means of lenses, achieved an efficiency of 37 percent due to the increased intensity of the collected energy. In general, solar cells of widely varying efficiencies and cost are now available.
Structure
Modern solar cells are based on semiconductor physics -- they are basically just P-N junction photodiodes with a very large light-sensitive area. The photovoltaic effect, which causes the cell to convert light directly into electrical energy, occurs in the three energy-conversion layers.

Two technologies that are currently used to harvest solar energy are the solar photovoltaic and solar thermal methods. Basically, solar photovoltaic technology (PV) involves the conversion of solar rays into electricity, which can then be fed into a grid or used separately to power lighting, heating and cooling systems as well as a wide range of appliances. Solar thermal technology, on the other hand, harnesses sunlight directly to produce solar power, which enables appliances such as solar cookers and water heaters to function without conventional electricity.

Worldwide production of PV cells increased 51% in 2007. Globally, SunPower panels are reported to be the most efficient solar PV panels on the market. The other major global producers are Kyocera, Sharp and Q – Cells. With rising oil prices and growing awareness of the need to adopt environment friendly energy sources, the market for photovoltaic technology is poised for healthy growth.