Solar panel operation

A solar panel is a module that uses the energy of solar radiation. Usually refers to the devices to produce hot water (usually domestic) and photovoltaic panels used to generate electricity.

Photovoltaic panels are composed of many cells (called photovoltaic cells) that capture the light radiation (photons from solar radiation). These photons impacting on the cell surface and there are absorbed by semiconducting materials, such as silicon, freeing electrons hitting the atoms to which they belonged, and the electrons begin to move through the material producing electricity in the form of low voltage DC. The structure consists of solar panels, among other things, for: a solar generator, a battery, a charge controller and inverter (optional). The batteries are storing the energy produced by the generator and gives us the possibility to use that stored energy in the days where there is a very low radiation or no sun is present. The regulator, as its name implies, is responsible for avoid overloading or excessive discharge in the tank, whichever is irreversible damage would occur. As the electric current type provided by solar panels is direct current, often using an inverter and / or power converter to convert direct current into alternating current, which is what we normally use in our homes, jobs and shops.

Although each solar cell provides a relatively small amount of energy, many of them spread over a large area (forming the solar panel) can provide enough energy to be useful. These cells are connected together as a series circuit in order to increase the output voltage of electricity, while several networks are connected parallel to increase power generation capacity that can provide the panel. To get the most amount of power the solar cells should aim at the sun.

In 2005 the biggest problem with solar panels was the cost, which has been down to 3 or $ 4 per watt. The price of silicon used for most panels is now tending to rise. This has led manufacturers to start using other materials and thinner silicon panels to lower production costs. Due to economies of scale, solar panels are less expensive as they are used and manufactured more. As production increases prices continue to fall in coming years.

One of the main uses is known to heat the water in the panels have a receiving plate and tubes circulating the liquid attached to it. The receiver (usually coated with a black selective coating) ensures the transformation of solar radiation into heat, while the liquid that circulates through the pipes carries heat to where it can be used or stored. The heated liquid is pumped to a power apparatus exchanger (a coil inside the storage compartment and an external device) where it leaves the heat and then circulates back to the panel to be reheated.

Theory and Construction

Crystalline silicon and gallium arsenide are typical choices of materials for making solar cells. The crystals of gallium arsenide are created especially for photovoltaic use, while silicon crystals are available in standard ingots produced cheaper mainly for the consumption of the microelectronics industry. Polycrystalline silicon has lower conversion efficiency but also lower cost so that ultimately their profitability is warranted.

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 (depending on brightness and efficiency of solar cell).

Crystalline ingots are sliced ​​into thin discs as a wafer, polished to remove damage caused by the cut. Dopants are introduced (impurities added to modify the conductive properties) within the wafers, and metallic conductors are deposited on each surface: a thin grid on the side where da sunlight and usually a flat blade on the other. Solar panels are built with these cells cut into appropriate. To protect the front surface damage caused by radiation or by the use of these links were in a glass cover and are grounded on a substrate (which may be a rigid panel or a soft blanket). Electrical connections are made in series-parallel to determine the total output voltage. The foundation and the substrate must be thermally conductive, since the cells are heated by absorbing infrared energy that is converted into electricity. Since cell heating reduces the operating efficiency it is desirable to minimize it. The resulting assemblies are called solar panels or solar groups.

If one quarter of pavements and buildings of the cities were converted into solar panels, these would provide enough energy for the city.