Photovoltaic modules
(Click to enlarge) The photovoltaic (misnamed as solar panels as a panel is a set of modules) are formed by a set of cells (photovoltaic cells) that produce electricity from light that strikes them.
PV modules consist of a number of photovoltaic cells that convert light into electricity. These cells depend on the photovoltaic effect by the light energy that produces positive and negative charges come in two different type semiconductor, thus producing an electric field capable of generating a current. PV modules, in addition to producing energy that can power a grid land use in electric vehicles and solar boats.
In 2005 the most important problem with PV modules was cost. The price of silicon used for most of the panels is now tending to rise. This has led manufacturers to start to use other materials and thinner silicon cells for lowering production costs. Due to economies of scale, solar panels are less expensive as used and produced more. As production increases, prices continue to fall in coming years.
Theory and Construction
Crystalline silicon and gallium arsenide are typical choices of materials for solar cells. The gallium arsenide crystals are created specially for photovoltaic use, while the silicon crystals are available in standard pig cheaper produced primarily for consumption of the microelectronics industry.
When exposed to direct sunlight, a cell of 6 cm diameter silicon can produce a current of about 0.5 amps at 0.5 volts (equivalent to an average of 90 W / m, usually in the range of 50-150 W / m², depending on brightness and solar cell efficiency). Gallium arsenide is more efficient than the silicon, but also more expensive.
Crystalline ingots are sliced into thin discs as a wafer, polished to remove damage caused by the cut. Introducing dopant (impurities added to modify the conductive properties) within the wafers, and metal conductors are deposited on each surface: a fine grid on the side where da sunlight and usually a flat sheet in the other. Solar panels are built with these cells cut into appropriate. Against damage on the front surface caused by radiation or by the same handling of these are the links in a glass cover and is built upon a substrate (which may be a rigid panel or a soft blanket). Electrical connections are made in series parallel for determining the total output voltage. The foundation and substrate must be thermally conductive, since the cells are heated by absorbing infrared energy that is converted into electricity. Because the heating of the cells reduces the efficiency of operation is desirable to minimize it. The resulting assemblies are called photovoltaic modules.
A photovoltaic module is a collection of photovoltaic cells. Although each solar cell provides a relatively small amount of energy, many of these spread over a large area can provide enough energy to be useful. To get the most energy photovoltaic cells should aim at the sun.
