About Solar Cells

A solar cell (also known as a photovoltaic cell) is a device that converts light energy into electrical energy. Solar cell is sometimes the term reserved for devices intended specifically to capture energy from sunlight. Photovoltaic cell is used when the light source is unspecified.

This device is used for only two functions: photogeneration of charge carriers (electrons and holes) in a light-absorbing material, and separation of the charge carriers to a conductive contact that will transmit the electricity. Called the photovoltaic effect, this conversion is in the field of research related to solar cells known as photovoltaics.

Solar cells have many applications and have long been used in situations where electrical power from the grid is unavailable. These are places such as in remote area power systems, Earth-orbiting satellites and space probes, consumer systems, e.g. handheld calculators or wrist watches, remote radiotelephones and water pumping applications.

Four generations of development:

First
Consisting of a large-area, the first generation photovoltaic is single layer p-n junction diodes, that is capable of generating usable electrical energy from light sources with the wavelengths of sunlight and are typically made using a silicon wafer. First generation photovoltaic cells are also known as silicon wafer-based solar cells, the dominant technology in the commercial production of solar cells, accounting for more than 86% of the solar cell market.

Second
Based on the use of thin-film deposits of semiconductors, the second generations of photovoltaic materials were initially designed to be high-efficiency, multiple junction photovoltaic cells. Later, the advantage of using a thin-film of material was noted, reducing the mass of material required for cell design. This contributed to a prediction of greatly reduced costs for thin film solar cells. Currently (2007) there are different technologies/semiconductor materials under investigation or in mass production, such as amorphous silicon, poly-crystalline silicon, micro-crystalline silicon, cadmium telluride, copper indium selenide/sulfide. Typically, the efficiencies of thin-film solar cells are lower compared with silicon (=wafer-based) solar cells, but manufacturing costs are also lower, so that a lower price in terms of $/watt of electrical output can be achieved. Another advantage of the reduced mass is that less support is needed when placing panels on rooftops and it allows fitting panels on light materials or flexible materials, even textiles.

Third
Third generation photovoltaics are unlike the previous two, broadly defined as semiconductor devices which do not rely on a traditional p-n junction to separate photogenerated charge carriers and include photoelectrochemical cells, Polymer solar cells, and nanocrystal solar cells.

Fourth
The fourth generation of photovoltaic cells is altogether very different from the other three. Utilizing biological organisms, such as bacteria like P. Argenellus Flavus, to create the biopolymers needed to generate a standing field.



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